hleaves@ruby.vcu.edu (EAVES,HUGH) (12/04/90)
Radio shack sells small conductive discs that attach to the bottom of 120v incandescent light bulbs. They claim that these discs will extend the life of your light bulbs up to 100 times. Does anybody know how these work? My theory was that a rectifier in the base would prevent the reversal of the magnetic field in the bulb due to the AC polarity change. This might reduce fatigue on the filament. (Just a guess, don't flame me for being stupid!) ******************************************************************************* ** Hugh L. Eaves ** Internet: hleaves@ruby.vcu.edu ** ** Medical College of Virginia ** Bitnet: hleaves@vcuruby ** ** Department of Human Genetics ** Voice: (804) 371-8754 ** ***************** All non-incendiary communication welcome! *******************
elec140@csc.canterbury.ac.nz (12/04/90)
In article <58335@brunix.UUCP>, hleaves@ruby.vcu.edu (EAVES,HUGH) writes: > Radio shack sells small conductive discs that attach to the bottom of 120v > incandescent light bulbs. They claim that these discs will extend the life of > your light bulbs up to 100 times. Does anybody know how these work? My theory > was that a rectifier in the base would prevent the reversal of the magnetic > field in the bulb due to the AC polarity change. This might reduce fatigue on > the filament. (Just a guess, don't flame me for being stupid!) > I don't think it's anywhere near that complex. What destroys incandescent light bulbs is turning them on and off. A cold bulb filament is almost a dead short, hence the initial current thru a bulb when it's turned on is very high, although this quickly reduces down to the design value as the filament heats up. It is this initial high current that blows bulbs (notice that almost all bulbs go when you turn them on?). I imagine the discs are simply resistors, with a resistance much less than the steady state resistance of the light bulb (hence they will have negliable effect once the bulb filament is up to temperature), but greater than the initial resistance of a cold bulb which will limit the startup current. Basically they would provide a soft-start facility for light bulbs! -- ********************************************************* Chris Kaiser Postgrad - Elec Eng Dept Canterbury University Christchurch, NEW ZEALAND E.MAIL: c.kaiser@elec.canterbury.ac.nz *********************************************************
morrison@cs.uiuc.edu (Vance Morrison) (12/04/90)
In <1990Dec4.113531.10096@csc.canterbury.ac.nz> elec140@csc.canterbury.ac.nz writes: >In article <58335@brunix.UUCP>, hleaves@ruby.vcu.edu (EAVES,HUGH) writes: >> Radio shack sells small conductive discs that attach to the bottom of 120v >> incandescent light bulbs. They claim that these discs will extend the life of >> your light bulbs up to 100 times. Does anybody know how these work? My theory >> was that a rectifier in the base would prevent the reversal of the magnetic >> field in the bulb due to the AC polarity change. This might reduce fatigue on >> the filament. (Just a guess, don't flame me for being stupid!) >> >bulbs go when you turn them on?). I imagine the discs are simply resistors, Hugh was right (the disks are rectifiers), but the reason why they make bulbs last longer is very simple. Since the diode effectively halves the duty cycle, will only consume (very roughly) half the power. The filament does not get as hot and thus the bulb last longer. So why don't manufactures just build the diode in? Because the efficiency of the bulb goes down the lower the filament temperature. Thus you get long life but low efficiency. Since light bulbs are cheap ($.25 to $.50) and energy is expensive ($5 for a 100W bulb over its lifetime), this is definately a false economy unless changing the bulb is a major pain. While I am at it, the new compact flourescents have both long life and high efficiency. They have a higher up front cost, but do pay for themselves with energy savings. Vance
skwu@boulder.Colorado.EDU (WU SHI-KUEI) (12/06/90)
In article <1990Dec4.042524.14018@ux1.cso.uiuc.edu> morrison@cs.uiuc.edu (Vance Morrison) writes: .... much omitted .... >So why don't manufactures just build the diode in? Because the efficiency >of the bulb goes down the lower the filament temperature. Thus you get >long life but low efficiency. Since light bulbs are cheap ($.25 to $.50) >and energy is expensive ($5 for a 100W bulb over its lifetime), this is >definately a false economy unless changing the bulb is a major pain. Spoken like a true representative of a light bulb maker! Since the life of a bulb approximates: Life = 1 / V ** 11 (the exponent varies between 10 and 12) while the efficiency (light output) drops almost linearly with reduced voltage, building the diode in would only reduce the sale of bulbs. Incidentally, a good source of long life bulbs is any electrical supply house that sell 125volt bulbs at reasonable price.
jgd@Dixie.Com (John G. DeArmond) (12/06/90)
skwu@boulder.Colorado.EDU (WU SHI-KUEI) writes: >Spoken like a true representative of a light bulb maker! Since the life of >a bulb approximates: > Life = 1 / V ** 11 (the exponent varies between 10 and 12) >while the efficiency (light output) drops almost linearly with reduced voltage, >building the diode in would only reduce the sale of bulbs. I believe light decreases as the square of the reduction in voltage but your point is well made anyway. Here is how to extend your bulb life indefinitely with practically (<1%) decrease in output. Place a negative tempco thermistor of the proper value in the lamp lead. The thermistor limits inrush and self-heats to a low resistance value in about a second. The inrush is what finally gets the bulb. I've been using them here for quite some time with an average line voltage of 130. My hall lights went from an average life of 2 weeks to not having changed one since I put the thermistors in about 3 months ago. Here are some part numbers, all available from DigiKey: 100 watt bulb 16 ohm cold ptn126 150 watt PAR flood 8 ohm cold ptn124 4 bulb fixture, 100 watt ea 5 ohm cold kc024n-nd Typical on resistance for the 16 ohm device is 1 ohm which means that it dissipates about a watt with a 100 watt bulb. I mount the thermistors in the same compartment with the bulb. This provides extra heat when the bulb is lit which decreases the on resistance even more plus it provides plenty of air space around the part. The part will rise about 60 degrees C over ambient when in operation so you don't want to insulate it or pack it in a closed box. John -- John De Armond, WD4OQC | "Purveyors of speed to the Trade" (tm) Rapid Deployment System, Inc. | Home of the Nidgets (tm) Marietta, Ga | {emory,uunet}!rsiatl!jgd | "Vote early, Vote often"
bobt@pogo.WV.TEK.COM (Bob Tidrick) (12/07/90)
In article <30670@boulder.Colorado.EDU> skwu@spot.Colorado.EDU (WU SHI-KUEI) writes: >while the efficiency (light output) drops almost linearly with reduced voltage, >building the diode in would only reduce the sale of bulbs. > >Incidentally, a good source of long life bulbs is any electrical supply >house that sell 125volt bulbs at reasonable price. Another thing that effects bulb life is the thickness of the envelope. I have three 40W bulbs in my house that are now over 12 years old. They are in my bathroom and are made of a very thick glass. One of them has a broken filiment but when it goes out, which is every couple of months or so, I give it a bump and it works again. BOY, HOW DID THE BULB MANUFACTURERS LET THIS ONE SLIP BY. A thicker envelope will reduce the amount of oxygen that assimilates through the glass to the filiment. Charging the envelope with an inert gas such as argon further extends the life of the bulb. From my experiance light bulbs are engineered to have a limited life. Another question. How can they sell Christmas lights for as little as $ 0.10 and a 40 watt bulb sells for nearly $2.00 ? Can it all be Volume? The design is basicly the same. There is only a few cents more material. I think we are getting ripped off two ways here. I usually don't get up on soap boxes. Some times they fall apart. -- Bob Tidrick GPID Engineering Tektronix Inc. Wilsonville OR.
elmquist@nachos.SSESCO.com (Chris Elmquist) (12/07/90)
In article <10183@pogo.WV.TEK.COM> bobt@pogo.WV.TEK.COM (Bob Tidrick) writes: [ some stuff about envolope thinkness deleted] > >A thicker envelope will reduce the amount of oxygen that assimilates through >the glass to the filiment. Charging the envelope with an inert gas such as >argon further extends the life of the bulb. This sure makes sense to me... >From my experiance light bulbs are engineered to have a limited life. This makes even more sense... >is basicly the same. There is only a few cents more material. I think we are >getting ripped off two ways here. Yup.. So, where do we find thick enveloped, argon filled incandescent bulbs? I am on the "light-bulb police" in our local condominium association. We are replacing outdoor bulbs like crazy. Sure would be nice to find some longer life units. The 10000 hr rating on these bulbs is at least a magnitude too high. Chris -- Chris Elmquist, N0JCF Internet: elmquist@SSESCO.com AMPRN: N0JCF@WB0GDB.MN.USA.NA BellNet: (612) 785-3516
larry@kitty.UUCP (Larry Lippman) (12/07/90)
In article <5232@rsiatl.Dixie.Com>, jgd@Dixie.Com (John G. DeArmond) writes: > >Spoken like a true representative of a light bulb maker! Since the life of > >a bulb approximates: > > > Life = 1 / V ** 11 (the exponent varies between 10 and 12) An exponent of 13 is more common. > >while efficiency (light output) drops almost linearly with reduced voltage, > >building the diode in would only reduce the sale of bulbs. I'm not certain what "efficiency" means here, but perhaps the original author is referring to lumens per watt. Using this definition, "efficiency" varies close to the *square* of the voltage. > I believe light decreases as the square of the reduction in voltage but > your point is well made anyway. Not exactly... It's *much* more significant than that. For a typical incandescent vacuum lamp of 10 lumens per watt, or for a typical gas-filled incandescent lamp of 16 lumens per watt, lumens vary as voltage is raised to an exponent of 3.4. Such exponents are derived from extensive empirical data collected over the years by manufacturers of incandescent lamps, and are not the result of any theoretical calculations. > Here is how to extend your bulb life indefinitely with practically (<1%) > decrease in output. Place a negative tempco thermistor of the proper > value in the lamp lead. The thermistor limits inrush and self-heats to > a low resistance value in about a second. > ... > I mount the thermistors in the same compartment with the bulb. While the above installation technique may function as intended, readers should be aware that such an "aftermarket" installation: (1) most likely voids the UL approval on the lighting fixture in question; (2) is a National Electrical Code (NEC) violation; (3) most likely violates local building codes because of (1) and (2); and (4) may result in some difficulty with insurance coverage in the event of a fire. Permissible wiring within lighting fixtures is tightly controlled and specified by the NEC due to elevated temperatures found within such fixtures. I know of no lamp life extender which is UL-approved for the series wiring installation (as described above) within a lighting fixture, and based upon my knowledge of UL "philosophy", I doubt that such a device could ever meet UL approval. UL does approve the various button-type devices which insert within the lamp socket for lamp life extension, with such devices utilizing diodes or thermistors. I would strongly urge readers to utilize such button-type devices instead of the above wiring suggestion. Why risk a fire? How could one possibly have a fire, you may ask? Simple. Consider a light bulb whose filament opens, with a short filament section drooping against a support wire, thereby creating a *much* lower resistance. While such lamp faults usually burn open within the lamp envelope, a virtual short circuit can also result. Most readers have probably seen the effects of a burned out lamp which is then jostled while under power. Consider now that we have such a low resistance fault drawing *much* more current than a normal lamp, and consider the effects of such overcurrent on the thermistor. It is quite possible that the thermistor could burn under such circumstances. The button-type devices are deemed safe because they are not only enclosed within the metal screw area of the lamp socket, but are further insulated by the dielectric surrounding the socket (often a ceramic material). > Here are some part numbers, all available from DigiKey: > 100 watt bulb 16 ohm cold ptn126 > 150 watt PAR flood 8 ohm cold ptn124 > 4 bulb fixture, > 100 watt ea 5 ohm cold kc024n-nd > > Typical on resistance for the 16 ohm device is 1 ohm which means that it > dissipates about a watt with a 100 watt bulb. ... > The part will rise > about 60 degrees C over ambient when in operation so you don't want > to insulate it or pack it in a closed box. The 16-ohm device is actually a Panasonic P/N PNT-126, and has a maximum rating of 0.6 watts. Its R25/R50 deg C resistance ratio is 2.3, which means that its resistance is still about 7 ohms at 50 deg C. I would find it difficult to believe that at 85 deg C ("60 degees C over ambient") its resistance would be as little as 1 ohm. 2.5 to 3 ohms seems more likely, which means we could be dissipating at least 2.5 watts. That's *FOUR* times the *maximum* rating of the thermistor! Also, the above thermistor series is primarily intended as a temperature measuring element, and not for any significant power dissipation in any protective circuit. That's why its only rated at 0.6 watts. In my opinion, a much better, simpler and lower-cost alternative to any type of thermistor device (even the button-type) is to find a wholesale electrical supply firm which will sell you lamps rated for 130 volts (instead of the usual 120 volts). Such 130 volt lamps are also available rated for low-temperature and "rough duty" service, and those suckers will usually last for years in a home environment. I have one above my kitchen sink (a bitch to replace because of a curtain rod) that has been running for almost *4* years with a *lot* of on-off cycles. Another very robust lamp available from a wholesale electrical distributor is rated for traffic signal use. The only disadvantage of this type of lamp which limits its application for home use is that it is available only in a clear envelope (i.e., not frosted). Larry Lippman @ Recognition Research Corp. "Have you hugged your cat today?" VOICE: 716/688-1231 {boulder, rutgers, watmath}!ub!kitty!larry FAX: 716/741-9635 {utzoo, uunet}!/ \aerion!larry
stevenw@disk.UUCP (Steven Weller) (12/07/90)
elec140@csc.canterbury.ac.nz writes: >In article <58335@brunix.UUCP>, hleaves@ruby.vcu.edu (EAVES,HUGH) writes: [Stuff about a rectifier in Radio Shack lightbulb extenders] >I don't think it's anywhere near that complex. What destroys incandescent light >bulbs is turning them on and off. A cold bulb filament is almost a dead short, >hence the initial current thru a bulb when it's turned on is very high, >although this quickly reduces down to the design value as the filament heats >up. It is this initial high current that blows bulbs (notice that almost all >bulbs go when you turn them on?). I imagine the discs are simply resistors, >with a resistance much less than the steady state resistance of the light bulb >(hence they will have negliable effect once the bulb filament is up to >temperature), but greater than the initial resistance of a cold bulb which will >limit the startup current. >Basically they would provide a soft-start facility for light bulbs! >-- >********************************************************* >E.MAIL: c.kaiser@elec.canterbury.ac.nz >********************************************************* An interesting idea. I had always assumed that they were rectifiers. They simply halve the power of the bulb, thereby reducing the temperature of the filament greatly and preventing destruction. Rectifiers are used because of the low power dissipation. On the other hand, filaments on AC last longer than those on DC. This is because the crystal boundaries of the tungsten "creep" with the current. Impurities are added to the metal to 'pin' the crystals and prevent this happening. The creep eventually thins the filament and causes not spots. So rectifying the current could reduce the life. The other alternative is a capacitor. It reduces the power dissipated in the bulb by phase-shifting the current. I do not know whether the size of a capacitor suitable for this purpose would be less than the pacake these devices come in, however. Does anyone know ? -- : Phone: (502) 425 9560 << Steven Weller >> Fax: (502) 426 3944 : : Windsor Systems, 2407 Lime Kiln Lane, Louisville, KY, 40222 USA : : "A substance almost, but not quite, entirely unlike tea" : : stevenw@disk.UUCP or uunet!ukma!corpane!disk!stevenw :
amichiel@rodan.acs.syr.edu (Allen J Michielsen) (12/07/90)
In article <4225@kitty.UUCP> larry@kitty.UUCP (Larry Lippman) writes: >In article <5232@rsiatl.Dixie.Com>, jgd@Dixie.Com (John G. DeArmond) writes: ... in a truly esoteric arguement of lumens and baked beans... 8-) >> Here is how to extend your bulb life indefinitely with practically (<1%) >> decrease in output. Place a negative tempco thermistor of the proper >> value in the lamp lead. The thermistor limits inrush and self-heats to >> a low resistance value in about a second. > While the above installation technique may function as intended, If you can't clearly see that the above 'application' isn't a functional solution then you shouldn't make ANY coment on it. I haven't reviewed the power ratings discussed, but believe (agree) that this type of application is outside the normal design parameters & specs, but probably within physical normally distributed (fire/explosioin) limits of the device(s). The key word there may well be probably, I have found a BIG difference in bulb life just by selecting 'major' manufacturers ir bulbs, AND not buying them in cheap/discount store packaging. Meaning major MFG bulbs in cheap looking packages in cheap discount houses aren't (always/sometimes/often) then same quality (and life) bulbs as those you usually can get at hardware store, expensive outlets, AND which have older type, more conservative packaging. > UL does approve the various button-type devices which insert within >the lamp socket for lamp life extension, with such devices utilizing diodes >or thermistors. > I would strongly urge readers to utilize such button-type devices >instead of the above wiring suggestion. Why risk a fire? The funny part here is that while ul listed, these button type jobs are a common cause of fires, and very popular (winning) lawsuit item. I have a friend that testifies and consults, and has made a ton of money off these little jobs blowing up. The UL rating was either a result of poor government inoperation or just a simple bribe. Can anyone list a part number for one of these that was made by & sold under the GE, Westinghouse, Sylvania name in any part of north america. al -- Al. Michielsen, Mechanical & Aerospace Engineering, Syracuse University InterNet: amichiel@rodan.acs.syr.edu amichiel@sunrise.acs.syr.edu Bitnet: AMICHIEL@SUNRISE
uchuck@pelham.med.unc.edu (Charles Bennett) (12/07/90)
In article <282@nachos.SSESCO.com> elmquist@nachos.SSESCO.com (Chris Elmquist) writes: > >I am on the "light-bulb police" in our local condominium association. >We are replacing outdoor bulbs like crazy. Sure would be nice to >find some longer life units. The 10000 hr rating on these bulbs >is at least a magnitude too high. > >Chris >-- >Chris Elmquist, N0JCF >Internet: elmquist@SSESCO.com > AMPRN: N0JCF@WB0GDB.MN.USA.NA > BellNet: (612) 785-3516 I was president of our homeowners association for 8 years and we had the same problems. We tried various solutions first shot was to use ABCO brand blubs, that helped but still had problems. We determined that our failure rate was caused by thermal shock (rain on lighted blubs from broken globes) and vibration (wind, etc. shaking filament). Our final solution was: 1) use blubs (sorry can't remember the brand) that were commercial type with 3 or 4 filament supports instead of just two, and 2) replace all globes with plastic equivalents instead of glass. Since then we have to replace 2 - 4 blubs per month out of a total of 80 lamp posts. Hope this helps. Chuck Bennett
larry@tapa.uucp (Larry Pajakowski) (12/08/90)
Most of the disks I've seen these days are diodes. What I'm looking for are some PTC thermisistor disks I purchased about 12 years ago from Brookstone I think. These softened the turn on transient and slightly reduced the voltage. It would take a 250W light in my garrage about 3 seconds to come up to full brightness. That same 250W light was still going strong when I moved out 2 years ago. Anybody know if these are still being manufactured? DigiKey among others carries the wire in flavor but the under the bulb is more convenient. Larry Pajakowski larry@tapa.uucp
bhoughto@cmdnfs.intel.com (Blair P. Houghton) (12/08/90)
In article <10183@pogo.WV.TEK.COM> bobt@pogo.WV.TEK.COM (Bob Tidrick) writes: >filiment but when it goes out, which is every couple of months or so, I give >it a bump and it works again. BOY, HOW DID THE BULB MANUFACTURERS LET THIS ONE >SLIP BY. Could you email me a copy of that bulb? Ours keep on going poof on us... :-) >Another question. How can they sell Christmas lights for as little as $ 0.10 >and a 40 watt bulb sells for nearly $2.00 ? Can it all be Volume? The design >is basicly the same. There is only a few cents more material. I think we are >getting ripped off two ways here. Doubtful. Bulbs are a commodity, probably with a minimal margins, being supplied by several companies. More likely it's not "volume" but volume :). A 40-watter takes up about ten times the space a little blinky xmas light does. It costs therefore about ten times as much to transport and store the things. They're also about a tenth as robust, so losses due to breakage are likely higher. Plus, the capital equipment used to manufacture the bigger bulbs has to be much more complicated, and there's probably more labor involved. Then also, I'll bet the regular bulbs are made in the USA, and the christmas lights...well... --Blair "Jin-gle-bells jin-gle-bells jin-gle all the--<zzzzzap!> Uh, who tripped on the tree?"
jgd@Dixie.Com (John G. DeArmond) (12/08/90)
amichiel@rodan.acs.syr.edu (Allen J Michielsen) writes: >In article <4225@kitty.UUCP> larry@kitty.UUCP (Larry Lippman) writes: > ... in a truly esoteric arguement of lumens and baked beans... 8-) >>In article <5232@rsiatl.Dixie.Com>, jgd@Dixie.Com (John G. DeArmond) writes: >>> Here is how to extend your bulb life indefinitely with practically (<1%) >>> decrease in output. Place a negative tempco thermistor of the proper >>> value in the lamp lead. The thermistor limits inrush and self-heats to >>> a low resistance value in about a second. >> While the above installation technique may function as intended, > If you can't clearly see that the above 'application' isn't a functional >solution then you shouldn't make ANY coment on it. I haven't reviewed the >power ratings discussed, but believe (agree) that this type of application >is outside the normal design parameters & specs, but probably within physical >normally distributed (fire/explosioin) limits of the device(s). Allen, you just gotta overlook Larry the Lid (as he's referred to in other groups.) I induced him to make an ass out of himself in comp.dcom.telecom a few months ago and he's been messing his britches to get even ever since. He's quite fond of quoting the hypothetical and or calculated answers as fact. Just a spoiled rich kid not getting his way. > The funny part here is that while ul listed, these button type jobs are >a common cause of fires, and very popular (winning) lawsuit item. I have >a friend that testifies and consults, and has made a ton of money off these >little jobs blowing up. The UL rating was either a result of poor government >inoperation or just a simple bribe. I'll second that motion. I tried some of the little buttons in a 4 bulb chandelier in my den. By the time they had failed and shorted under 100 watt bulbs, they had emitted a large quantity of smoke and had fried to a blakened crisp. *I* consider them a fire hazard after my experience. Let's get back to the thermistors. I rarely post the entire history of events that leads up to my recommendations. After all, I'm not writing magazine articles here on the net. I do thoroughly test them whenever possible. This is such a case. The thermistors specified are meant for surge or inrush limiting applications. I thoroughly tested the application before I made the recommendation. Because this is a new application for the parts, different than the normal use in switchmode powersupplies, I set up a test environment in my lab that consisted of a light fixture representative of what is in my house, a variac to vary the applied voltage and a thermocouple datalogger to record what thermal events occured. One thermocouple was fastened via thermal epoxee to the thermistor and the other to the base of the lamp socket. A 100 watt bulb and a PAR reflector lamp were tested. The worst conditions observed were with the 16 ohm thermistor and the 100 watt lamp. The 60 degree C rise was the maximum measured. What was interesting was that the base of the socket got hotter than the thermistor. Considering that the socket was the type insulated with paper inside a brass-like shell, I'll let you draw your own conclusions. Let's look at some of Larry the Lid's hallucinations and compare them to experimental data. From here on down, the single ">"s are Larry the Lid's comments. > While the above installation technique may function as intended, >readers should be aware that such an "aftermarket" installation: (1) most >likely voids the UL approval on the lighting fixture in question; Since doing anything to a fixture that deviates from the UL test conditions voids the approval, (such as putting all those 100 watt bulbs in "60 watt max" sockets), at least one can say that "voiding" is common and does not cause many fires. As we'll see, the *practical* safety is not degraded and if anything, is enhanced. >(2) is >a National Electrical Code (NEC) violation; This one is a bit easier to refute. A careful purusual of the 1990 NEC will turn up only vague admonitions about fixture designs such as 410-24(a) "Insulation - Fixtures shall be wired with conductors having insulation suitable for the environmental conditions, current, voltage and temperature to which the conductors will be subjected." 41-68 "Fixtures shall be so constructed that the adjacent combustible material will not be subject to temperatures in excess of 90 degrees C." (referring to the special case of recessed fixtures.) In other words, use good engineering judgement and keep the surface temperature of adjacent materials below certain values. >(3) most likely violates local >building codes because of (1) and (2); Hardly. Most areas adopt the NEC in total. I've had other occasions to check here in Cobb county and know that this is the case here. Any hands wringers should probably check with their local electrical inspectors before improving the life of their lightbulbs. Don't be surprised if you get a "Duh, I don't know" if you do ask. While you're asking, be sure and ask about those extension cords that just sorta became a part of the lampand those non-waterproof outlets in your open garage and all the other little things that aren't strictly according to code. > Permissible wiring within lighting fixtures is tightly controlled >and specified by the NEC due to elevated temperatures found within such >fixtures. I know of no lamp life extender which is UL-approved for the >series wiring installation (as described above) within a lighting fixture, >and based upon my knowledge of UL "philosophy", I doubt that such a device >could ever meet UL approval. Actually the NEC does not address the subject. The closest references in the index are to "thermal devices" and "thermal overcurrent protectors" and these refer to motor protection. And since we know that UL approves the diode devices which WILL flame when they fail, we could postulate that passing UL testing for a non-flammable, non-flaming and non-smoking device would be trivial. > How could one possibly have a fire, you may ask? Simple. Consider >a light bulb whose filament opens, with a short filament section drooping >against a support wire, thereby creating a *much* lower resistance. While >such lamp faults usually burn open within the lamp envelope, a virtual >short circuit can also result. Most readers have probably seen the effects >of a burned out lamp which is then jostled while under power. Consider >now that we have such a low resistance fault drawing *much* more current >than a normal lamp, and consider the effects of such overcurrent on the >thermistor. It is quite possible that the thermistor could burn under >such circumstances. > >>The button-type devices are deemed safe because >they are not only enclosed within the metal screw area of the lamp socket, >but are further insulated by the dielectric surrounding the socket (often >a ceramic material). But since we know that the button devices, when subjected to the high lamp base temperatures, DO catch fire and burn, we know that this statement is false. But let's address the issue Larry the Lid raises above. Even though we know that a filament short is always blown away instantly upon contact and because we could speculate that a lamp construction that would allow a continuous short between electrodes could never be approved, it is reasonable to wonder what a hard short would do to the termistor. So in the interest of completeness, I decided to test his hypothesis. Since power dissipation would be worst case with a cold, high resistance termistor, my testing was done at ambient. My test rig is simplicity itself - a ptn-126 thermistor clipped in a Jesus Cord (a 120 volt cord with aligator clips on the end - makes you yell "JEEEESUS" when they get together and can aid you in meeting Him if you grab 'em :-) and laying on a paper towel for fuel. Plug the cord in and ... POP! The thermistor blows apart instantly. No flame and no smoke. This is, of course, many times more severe than conditions that exist in the light fixture. We must remember that the ambient temperature in a fixture is MUCH higher than the 60 degree rise, (80 degree C absolute) measured on the surface of the thermistor. I plan on setting up an accelerated life test with a cycle timer that will cycle the lamp on and off at about 10 0r 15 second intervals. I'll probably conduct at least part of the test with fiberglass insulation wrapped around the thermistor to see if that makes any differnece. I'll post any interesting results. (Well hey! It's another excuse to throw another 8048 at something :-) > Typical on resistance for the 16 ohm device is 1 ohm which means that it > dissipates about a watt with a 100 watt bulb. ... > The part will rise > about 60 degrees C over ambient when in operation so you don't want > to insulate it or pack it in a closed box. > The 16-ohm device is actually a Panasonic P/N PNT-126, and has >a maximum rating of 0.6 watts. Its R25/R50 deg C resistance ratio is 2.3, >which means that its resistance is still about 7 ohms at 50 deg C. I >would find it difficult to believe that at 85 deg C ("60 degees C over >ambient") its resistance would be as little as 1 ohm. 2.5 to 3 ohms >seems more likely, which means we could be dissipating at least 2.5 >watts. That's *FOUR* times the *maximum* rating of the thermistor! The actual *MEASURED* (as opposed to hypothesized or made up) voltage drop across a PTN-126 while wired in series with a 100 watt bulb ranges from 0.8 to 1.0 volts as measured with a Fluke 8800A 5-1/2 digit voltmeter with the true RMS option installed and an NBS (ne NITS) traceable calibration. Since the measured current is just a bit under an amp, the computed resistance is about an ohm and the power dissipation is about a watt. We know from experience that Larry finds experimental data "difficult to believe". Fabricated numbers are *SO* much more tidy. > > Also, the above thermistor series is primarily intended as a >temperature measuring element, and not for any significant power dissipation >in any protective circuit. That's why its only rated at 0.6 watts. Low ohm negative tempco thermistors with significant watt ratings are designed for inrush applications and make pretty poor measuring devices, as a glance at the thermistor curves would show. Since the 600 milliwatt rating is for worst-case conditions, I have no problem at all operating the device at higher dissipations under less severe thermal conditions. After all, that is all that really matters. One could run almost any dissipation through the device if the cooling were adequate. I've always considered operating temperatures of less than 100 degrees C in resistance devices to be quite acceptable. > > In my opinion, a much better, simpler and lower-cost alternative >to any type of thermistor device (even the button-type) is to find a >wholesale electrical supply firm which will sell you lamps rated for >130 volts (instead of the usual 120 volts). Such 130 volt lamps are >also available rated for low-temperature and "rough duty" service, and >those suckers will usually last for years in a home environment. I have >one above my kitchen sink (a bitch to replace because of a curtain rod) >that has been running for almost *4* years with a *lot* of on-off cycles. > > Another very robust lamp available from a wholesale electrical >distributor is rated for traffic signal use. The only disadvantage of >this type of lamp which limits its application for home use is that it >is available only in a clear envelope (i.e., not frosted). I can't argue with this advice. If you can stand the reddish light and the glare, go ahead. I simply find that the the process of soft-starting a regular bulb gives me the best of both worlds - a good color temperature and long life. John -- John De Armond, WD4OQC | "Purveyors of speed to the Trade" (tm) Rapid Deployment System, Inc. | Home of the Nidgets (tm) Marietta, Ga | {emory,uunet}!rsiatl!jgd | "Vote early, Vote often"
wb8foz@mthvax.cs.miami.edu (David Lesher) (12/09/90)
I did the math once when I was tempted by a cheap lamp. ISTM that over the lifetime of the GE 75 watt lamp, it used $11.00 of electricity at my residential rates. The lamp cost about $0.39 on sale. I stopped worrying about the price of the lamps after that. I DO worry about their efficiency. -- A host is a host from coast to coast.....wb8foz@mthvax.cs.miami.edu & no one will talk to a host that's close............(305) 255-RTFM Unless the host (that isn't close)......................pob 570-335 is busy, hung or dead....................................33257-0335
bill@videovax.tv.tek.com (William K. McFadden) (12/11/90)
I didn't really want to get involved in this discussion, as many
seem to know more about light bulbs than I, but let's look at some
tradeoffs. Using the empirical formulas:
LIFE = RATED_LIFE * (APPLIED_VOLTAGE/RATED_VOLTAGE)^-12
and
LUMENS = RATED_LUMENS * (APPLIED_VOLTAGE/RATED_VOLTAGE)^3.5
and
CURRENT = RATED_CURRENT * (APPLIED_VOLTAGE/RATED_VOLTAGE)^0.55
These formulas come from an internal publication by my company,
which I feel to be trustworthy.
Let's assume for the sake of argument that we have 100 watt 120V
and 130V bulbs with the same rated life. This may not be a good
assumption, but it will allow us to look at operating cost as a
function of voltage rating. Hence, running the 130V bulb on 120V
yields about 2.5 times the life and 3/4 the light output (in lumens)
of the 120V bulb. In addition, the 130V bulb consumes 96% as much
current at 120V as it does at 130V.
In my region, electricity runs about $0.05 per KWH. Assuming bulb
life is rated at 1000 hours, the 130V bulb will run about 2500
hours, drawing 96 watts and consuming 230 KWH at a cost of $11.50,
or $4.60 per 1000 hours of life. Meanwhile, the 120V bulb runs
for 1000 hours, drawing 100 watts and consuming 100 KWH at a cost
of $5.00, or $5.00 per 1000 hours.
It is obvious that, unless the bulbs are very expensive, the purchase
price of the bulbs is a very small part of the total cost. In
regions with costlier power, this is even more so. We can probably
go as far as to ignore the cost of buying the bulb. Hence, over
its lifetime, the 130V bulb costs almost as much to operate as the
120V bulb and generates only 75% the light output. Unless changing
bulbs is very inconvenient, most people would be better off with
a lower wattage (e.g., 75W) 120V bulb. Lower wattage bulbs last
longer, too.
In areas with high line voltage, 130V bulbs may be the only choice.
BTW, Digi-Key has some "inrush current limiters" (NTC thermistors)
that are designed to handle currents over an amp and have "on"
resistances under an ohm. Perhaps one of these would be more
suitable for light bulb current limiting than the thermistors that
have been mentioned so far.
Comments?
--
Bill McFadden Tektronix, Inc. P.O. Box 500 MS 58-639 Beaverton, OR 97077
bill@videovax.tv.tek.com, {hplabs,uw-beaver,decvax}!tektronix!videovax!bill
Phone: (503) 627-6920 "The biggest difference between developing a missle
component and a toy is the 'cost constraint.'" -- John Anderson, Engineer, TIwhester@isis.cs.du.edu (William R. Hester) (12/12/90)
I've found the best solution is to purchase incandescent bulbs rated for
130 VAC...these are industrial types not found in your grocery store.
When operated below rated voltage, the light output drops a bit, but the
operating life is extended to approx 260% of the hrs. at 130 volts.
The formula for operating indandescent lamps at other than rated voltage
is:
%Life = (Rated Volts/Actual Volts)^(13.1)
As you can see, the life is very sensitive to the actual voltage used.
I'm not sure, however, how reduced voltage will affect the operation of
halogen cycle types...I guess it stops the tungsten replacement cycle and
actually reduces bulb life...???
--
Bill Hester, Ham Radio N0LAJ, Denver CO., USA | N0LAJ @ W0LJF.CO.USA.NA
Please route replies to: whester@nyx.cs.du.edu or uunet!nyx!whester
Public Access Unix @ University of Denver, Denver Colorado USA
(no official affiliation with the above university)e221a-bx@libra.Berkeley.EDU (Charlie Sullivan) (12/13/90)
In article <1990Dec11.163848.21840@isis.cs.du.edu> whester@isis.UUCP (William R. Hester) writes: >I'm not sure, however, how reduced voltage will affect the operation of >halogen cycle types...I guess it stops the tungsten replacement cycle and >actually reduces bulb life...??? At significantly reduced voltage, the halogen cycle stops working, and the bulb wall starts to blacken, due to evaporated tungsten. This could lead to shortened life than at nominal voltage. But it would take a very low voltage, like from having the lamp on a dimmer. If it starts to happen, you can crank the voltage back up and fix the bulb. About bulb life extenders and the argument about whether they are PTCs or diodes: Surprise! You're both right. Both types exist. In addition to the fire hazards that have been mentioned, I have heard from a researcher at one of the major lamp companies that stress at turn-on is not significant in decreasing lamp life. True, lamps usually die at turn-on, but only when they are within eight hours of failure anyway. So a perfect soft start would only gain you about 4hrs. average life. The way these things actually increase lamp life is by dropping some voltage in normal operation. As others have pointed out, life is very sensitive to operating voltage. A diode is a more efficient (and safer) way to drop the voltage than a resistor. Even so, the efficiency of the lamp goes down at reduced voltage, and a diode cuts the voltage quite a bit. A dimmer is similar to a diode in that (unlike a resistor) it doesn't dissipate much power. It has the advantage that the voltage reduction is continuously adjustable. Instead of fussing over the optimum in the life/efficiency tradeoff in incandescants, why not have have it both ways? Buy compact fluorescents. Charlie Sullivan charless@cory.Berkeley.EDU EE grad student--U.C. Berkeley usual disclaimers
jgk@osc.COM (Joe Keane) (12/13/90)
I have some incandescent lamp curves in front of me, and they pretty much agree with the formulas others have posted. At 110% of rated voltage the power consumed is 115% of normal, the light output is 140% of normal, and the expected life is 40% of normal. Conversely, at 90% of rated voltage the power consumed is 85% of normal, the light output is 70% of normal, and the expected life is 400% of normal. You can see that it's easy to get a very large increase in life by dropping the supply voltage a bit. This fact is frequently re-discovered, as if no one knows it and the light bulb companies are conspiring to make you buy more. It's good to know if you only care about lamp life, say they're in a remote location and hard to change. The problem is the resulting loss in efficiency; notice that at 90% of rated voltage the lumens per watt is down to about 80% of normal. If you're thinking economically, you should keep in mind that the cost of a light bulb is much lower than the cost of the power it consumes during its lifetime. The conclusion is that if you're dropping the supply voltage, or equivalently using a higher rated voltage, you're making a mistake. If you're happy with the reduced light output, then you should use a lower wattage bulb with the right voltage. You'll use less power and also get better color. Some sort of inrush current limiter and/or voltage regulator would be a good idea, since start-up and high-voltage periods consume a disproportionate amount of the lamp's life. But that's a lot more complicated than a simple rectifier.
phil@brahms.amd.com (Phil Ngai) (12/14/90)
In article <4078@osc.COM> jgk@osc.COM (Joe Keane) writes: |The conclusion is that if you're dropping the supply voltage, or equivalently |using a higher rated voltage, you're making a mistake. If you're happy with |the reduced light output, then you should use a lower wattage bulb with the |right voltage. You'll use less power and also get better color. If you're concerned about bulb life, use a compact fluorescent. Most of them are rated around 10K hours. If you're concerned about cost, use a C.F. Over the life of the bulb it will pay itself back many times. I can not see any reason to use incandescents anymore, unless you are getting free power. --
mcovingt@athena.cs.uga.edu ( Michael A. Covington) (12/14/90)
In article <1990Dec13.172348.20146@amd.com> phil@brahms.amd.com (Phil Ngai) writes: >If you're concerned about bulb life, use a compact fluorescent. Most >of them are rated around 10K hours. If you're concerned about cost, >use a C.F. Over the life of the bulb it will pay itself back many >times. I can not see any reason to use incandescents anymore, unless >you are getting free power. > >-- I can. I'm an amateur astronomer and I have to be away from fluorescent lights for several hours before doing any observing that requires really good night vision. The high UV output of fluorescents tends to kill night vision. On the other hand, it might be good for people who feel despondent due to the lack of sunlight in winter. I also keep reptiles (lizards) as pets and they *thrive* on fluorescent lights. Lizards are accustomed to a tremendous amount of sunlight and they use it to synthesize their own vitamin D (not quite the same as the vitamin D in mammals). Without sunlight or fluorescent lights, they die.
roy@phri.nyu.edu (Roy Smith) (12/14/90)
phil@brahms.amd.com (Phil Ngai) writes: > I can not see any reason to use incandescents anymore, unless > you are getting free power. I have a one of those draftsman type desk lamps that has written on it in big black magic marker, "2.8%". That's what me and my college roommate figured out the conversion efficiency from electricity to light was; Watts in vs. Lumens out with some E=h*Lambda (I hope that's the right formula, it's been a while) for a mid-visible-spectrum wavelength thrown in to convert to Watts of light out. As I remember, that was for a smallish (40 or 60) Watt bulb; I suspect the larger sizes are more efficient. Anyway, much as I think the compact flourescents are a good idea, I can see two reasons not to use them. First, the light is ugly. I have found that about a 1:1 mix by wattage of incandescant and flourescent lights give the most pleasing illumination; much nicer than either alone. Second, the compact floursecents just aren't compact enough. Con Edison is having a promotion now; you can buy up to 10 CFs for $3-5 each depending on wattage. The flyer they sent around has the dimensions of each bulb. I carefully measured most of my lamps and ceiling fixtures and there just isn't enough room for the CF's unless I'm willing to use the smallest sizes and get substantially less light out. What's the prognosis for this in the future? Any chance better technology will shrink the CFs another 20% in a couple of years? That's about what it would take to do it. Personally, I save energy by being a lunatic about turning off lights when I leave a room. Drives my wife nuts when I nag her to do the same. I do suspect, however, that the power I waste by leaving my Sun workstation in the office on all the time far exceedes what I save by living in the dark ages at home :-( -- Roy Smith, Public Health Research Institute 455 First Avenue, New York, NY 10016 roy@alanine.phri.nyu.edu -OR- {att,cmcl2,rutgers,hombre}!phri!roy "Arcane? Did you say arcane? It wouldn't be Unix if it wasn't arcane!"
schumach@convex.com (Richard A. Schumacher) (12/14/90)
Okay, several people have stated that in-rush (high initial current) reduces an incandescent's life. How? What's the mechanism?
bill@videovax.tv.tek.com (William K. McFadden) (12/15/90)
In article <1990Dec13.172348.20146@amd.com> phil@brahms.amd.com (Phil Ngai) writes: >In article <4078@osc.COM> jgk@osc.COM (Joe Keane) writes: >I can not see any reason to use incandescents anymore, unless you >are getting free power. Because X-10 fluorescent wall switches cost 5X as much as incandescent. In addition, the fluorescent X-10 switch requires a neutral lead to the switch box, which most houses don't have. It's going to be a long time before this pays for itself. Of less importance is you lose dimming with fluorescent. (I can live without this.) This is unfortunate. I'd love to change all my lights to fluorescent, but I don't want to give up my X-10. I am hoping either X-10 or the bulb and light fixture makers will address this problem. -- Bill McFadden Tektronix, Inc. P.O. Box 500 MS 58-639 Beaverton, OR 97077 bill@videovax.tv.tek.com, {hplabs,uw-beaver,decvax}!tektronix!videovax!bill Phone: (503) 627-6920 "The biggest difference between developing a missle component and a toy is the 'cost constraint.'" -- John Anderson, Engineer, TI
phil@brahms.amd.com (Phil Ngai) (12/15/90)
roy@phri.nyu.edu (Roy Smith) writes: > Anyway, much as I think the compact flourescents are a good idea, I >can see two reasons not to use them. First, the light is ugly. I have There are some fluorescent lamps with ugly light. But there are also some CFs with very good light. The Philips SF*18 is a good example. If you haven't seen them, you should. >carefully measured most of my lamps and ceiling fixtures and there just >isn't enough room for the CF's unless I'm willing to use the smallest sizes I'm willing to change my fixtures. Perhaps someday you won't have to (but there are probably limits to the intensity level of CF and therefore how small they can get) but I don't want to wait. --
larry@kitty.UUCP (Larry Lippman) (12/15/90)
This article has two sections. The first covers technical issues, and its end is clearly marked for those readers who wish to stop reading at that point. The second is designed to give Mr. DeArmond an "attitude adjustment" for his propensity to Tell Tall Tales, and it reveals some facts which may assist readers in evaluating his credibility. There are also fascinating excerpts from previous articles posted by Mr. DeArmond, courtesy of a CD-ROM Usenet archive. I dislike having to write the second part of this article, but everyone has a limit as to how much bullshit and name-calling they will silently and politely endure. In previous articles I hinted to Mr. DeArmond that people in glass houses should not throw stones, but he didn't get the message. He *will* get the message this time. In article <5265@rsiatl.Dixie.Com>, jgd@Dixie.Com (John G. DeArmond) writes: > >>In article <5232@rsiatl.Dixie.Com>, jgd@Dixie.Com (John G. DeArmond) writes: > >>> Here is how to extend your bulb life indefinitely with practically (<1%) > >>> decrease in output. Place a negative tempco thermistor of the proper > >>> value in the lamp lead. [description of modifying light fixture deleted] > amichiel@rodan.acs.syr.edu (Allen J Michielsen) writes: > > The funny part here is that while ul listed, these button type jobs are > >a common cause of fires, and very popular (winning) lawsuit item. I have > >a friend that testifies and consults, and has made a ton of money off these > >little jobs blowing up. The UL rating was either a result of poor government > >inoperation or just a simple bribe. UL disagrees with these statements. Perhaps you can prove otherwise? > I'll second that motion. I tried some of the little buttons in a 4 bulb > chandelier in my den. By the time they had failed and shorted under > 100 watt bulbs, they had emitted a large quantity of smoke and had > fried to a blakened crisp. *I* consider them a fire hazard after my > experience. Amazing! Mr. DeArmond never told us about his alleged experience with the button-type devices until *after* Allen Michielsen stated that they were a fire hazard. Out of curiosity, I called a contact at UL (708/272-8800) who referred me to an engineer responsible for lighting fixture safety (name upon request). The engineer with whom I spoke, who was quite familiar with the button-type lamp life extenders, had no knowledge of *any* fires caused by UL-approved devices inserted in lamp sockets. My curiosity being piqued, I called the IES (Illuminating Engineering Society, 212/705-7919) and an engineer who deals with lighting safety issues, John Briggs, was kind enough to speak with me out of professional courtesy since I am not an IES member. Mr. Briggs was familiar with the button-type devices, and was unaware of any fires caused by their use. At Mr. Briggs' suggestion I contacted the General Electric Lighting Products Division (216/266-3900) and spoke with a technical specialist who advised me that he knew of no fire hazard from the use of such button-type devices. Mr. Briggs offered the opinion that if anyone had any prejudice *against* lamp life extenders it would be a lamp manufacturer. Since this was getting curioser and curioser, I then contacted the NFPA (National Fire Protection Association, 617/770-3000) and spoke with an engineer in their Electrical Engineering department, Mike Ode, who was not aware of these devices being a fire hazard. At Mr. Ode's suggestion, I then spoke with Ken Taylor in the NFPA Fire Analysis Division, who had no specific data as to these devices being a fire hazard. Mr. Taylor did give me an interesting statistic: approximately 3,200 fires per year are caused by lamps and lighting fixtures. There was only one more organization left to call - which was fortunate since I have only a finite amount of coffee break time to spend on this pursuit. :-) I called the CPSC (Consumer Product Safety Commission, regional office, 212/264-1130) and spoke with Robert Moro, who stated that their agency did have about half a dozen complaints concerning *one* particular button-type device which was imported and did *not* have UL approval. About half of these complaints pertained to electrical shock resulting from the exposed portion of the metal lamp screw base (since a lamp can no longer screw into a socket as deeply with a button-type device). The CPSC had not as yet reached any final determination on these complaints, and they had as yet no conclusive information that any fires had actually been caused by such devices. Clearly there is a grain of truth to these devices being the subject of complaint, but there does not yet appear to be conclusive data that they have been the *direct* cause of any fire. If such were the case, one might think that UL, IES, NFPA and General Electric would be aware of the situation. It is important to bear in mind that there are *3,200* fires each year caused by lamps and lighting fixtures, and that even if such a button-type device were installed when such a fire occurred, one cannot simply conclude that the mere presence of such device caused the fire. Likewise, I had not previously heard of any fires caused by the UL-approved devices, which is why in my original article I stated that UL considered them safe because they were confined within the metal barrier of the lamp socket. It may also help readers to know that typical base temperatures of incandescent lamps in the range of 60 to 100 watts run from 194 to 208 deg F (data taken from NFPA handbook). It does not seem likely that the button-type devices will get hot enough to destroy any thermosetting plastic insulating material used in their manufacture, considering that most thermoset plastics used for electrical component manufacture (like allyls, phenolics, etc.) will withstand temperatures of at least 350 deg F. > I tried some of the little buttons in a 4 bulb > chandelier in my den. By the time they had failed and shorted under > 100 watt bulbs, they had emitted a large quantity of smoke and had > fried to a blakened crisp. Since a chandelier is open, with heat rapidly dissipated through convection, and since under such circumstances the lamp base temperature is not likely to exceed 212 deg F, what, pray tell, caused the devices to allegedly "emit a large quantity of smoke and fry to a blackened crisp"? Enquiring minds would like to know why Mr. DeArmond seems to be one out of only a handful of persons in the *entire* country with a truly specific claim as to the burning of these button-type devices. In addition, do Mr. DeArmond's alleged devices bear UL-approval? If not, then why would a person as allegedly astute as Mr. DeArmond purchase such a device lacking UL-approval? Readers who make it through to the end of this article may well develop a theory as to Mr. DeArmond's claims, however. > The thermistors specified are meant for surge or inrush limiting > applications. ALL of the thermistors in the Panasonic ERT-D-series and the Keystone RL-series specified by Mr. DeArmond are intended for temperature measurement, temperature compensation, time delay, and limiting for signal (*not* power) circuits only. The thermistors in these series have 26 AWG and 24 AWG wire leads, which ought to be a clue as to their intended application - if one actually had such a thermistor in their possession. But this wire lead gage data is not found in the Digi-Key catalog. What Mr. DeArmond failed to find in his Digi-Key catalog, because it was somewhat buried at the upper right hand corner of a page which otherwise listed varistors, was the one series which actually is suitable for power inrush limiting. Those thermistors, the Keystone CL-series, have 18 AWG and 22 AWG wire leads, are quite suitable for lamp or power applications, and have explicitly specified current ratings from 1.1 to 12 amps. The best part is that at full rated current THEY DON'T GET ANY HOTTER THAN 25 DEG C. Based upon the thermistor selection listed in the Digi-Key catalog, it would be utterly absurd to consider anything other than the Keystone CL-series for a lamp application. Why didn't Mr. DeArmond tell us about *that* series? Was it because he overlooked it while trying to make the best of other part numbers in support of his latest Tall Tale? But, this situation gets better and better, so please be patient... > I thoroughly tested the application before I made the recommendation. I know of some oceanfront property for sale in Arizona. :-) > Because this is a new application for the parts, different than the > normal use in switchmode powersupplies It's a "new application" alright, because none of the thermistors mentioned by Mr. DeArmond are intended for "switchmode powersupplies". > I set up a test environment in my > lab that consisted of a light fixture representative of what is in my > house, a variac to vary the applied voltage and a thermocouple datalogger > to record what thermal events occured. One thermocouple was fastened via > thermal epoxee to the thermistor and the other to the base of the lamp > socket. A 100 watt bulb and a PAR reflector lamp were tested. My gawd, I'm impressed. > > While the above installation technique may function as intended, > >readers should be aware that such an "aftermarket" installation: (1) most > >likely voids the UL approval on the lighting fixture in question; > > Since doing anything to a fixture that deviates from the UL test conditions > voids the approval, (such as putting all those 100 watt bulbs in "60 > watt max" sockets), at least one can say that "voiding" is common and > does not cause many fires. As we'll see, the *practical* safety is > not degraded and if anything, is enhanced. Self-proclaimed "practical safety" which violates explicit rules, regulations and standards (i.e., UL, NEC and building codes) does not go very far with insurance companies or building inspectors. > >(2) is a National Electrical Code (NEC) violation; > Hardly. Most areas adopt the NEC in total. I've had other occasions to > check here in Cobb county and know that this is the case here. Which means that use of a light fixture no longer having UL approval violates the local building code in Marietta, GA. Now, why is this *important*? Because the discovery of such an intentional violation may void insurance coverage in the event of a fire. Consider the following quotation from a Hartford insurance policy: "We will not pay for loss or damage caused by or resulting from any of the following ... c. Faulty, inadequate or defective: (1) Planning, zoning, development, surveying, siting; (2) Design, specifications, workmanship, repair, construction, renovation, remodeling, grading, compaction; (3) Materials used in repair, construction, renovation or remodeling; or (4) Maintenance; of part or all of any property on or off the described premises." Who wants to risk losing the economic investment in their house and personal possessions by taking Mr. DeArmond's advice and modifying a light fixture to save a paulty few dollars per year? But Mr. DeArmond has nothing to worry about. He'll just tell the insurance company that he made measurements with a gen-U-wine FLUKE 8800A 5-1/2 digit DVM, that while 12 years old and obsolete, still has NBS-traceable calibration! :-) > But let's address the issue Larry the Lid raises above. Even though we > know that a filament short is always blown away instantly upon contact A filament short is *usually* blown away because there is no device in series with the lamp to create impedance and limit current. A series thermistor, even in the hot state, may well limit current such that neither the shorted filament nor thermistor itself will have enough energy to instantaneously open. The actual instantaneous fault current available from a typical 20 ampere electrical branch circuit may reach the hundreds of ampere range, with a low resistance fault within a lamp usually blowing out in several cycles - which is usually not long enough to trip an overcurrent device. It doesn't take much imagination to see how even 1 ohm of series resistance can drastically reduce current such that the energy necessary to open an internal lamp fault is no longer available. Consider this example, which should be intuitive to many readers. A 2" piece of 28 AWG wire connected to the 18 AWG conductors of a line cord will probably blow away in a fraction of a second if the line cord were plugged into an AC outlet. If an appropriate series impedance that limited current were now added to the circuit, the 28 AWG wire would first become red hot (perhaps for a long time) before opening. Also, that series impedance might itself get rather hot in the process. > and because we could speculate that a lamp construction that would allow > a continuous short between electrodes could never be approved, Mr. DeArmond should take apart a few different models of light bulbs and see how filament support wires can well be deflected against broken filament sections to create low resistance faults in a lamp failure. Such light bulbs are all UL-approved. > Since power dissipation would be worst case with a cold, high resistance > termistor, my testing was done at ambient. My test rig is simplicity > itself - a ptn-126 thermistor clipped in a Jesus Cord (a 120 volt cord > with aligator clips on the end - makes you yell "JEEEESUS" when they get > together and can aid you in meeting Him if you grab 'em :-) and laying on > a paper towel for fuel. Plug the cord in and ... POP! The thermistor > blows apart instantly. No flame and no smoke. This is, of course, many > times more severe than conditions that exist in the light fixture. One can perform the same test and achieve the same results with a 1N4005 rectifier diode; I suspect that this is intuitive to many readers. Earlier in his article, Mr. DeArmond seems to have taken the bait planted by Allen Michielsen and agreed that the diode devices are a hazard. Well, if both a diode device and a thermistor device will "blow apart instantly", then why is Mr. DeArmond's thermistor device *safe*, but the diode device a *hazard*? > I plan on setting up an accelerated life test with a cycle timer that > will cycle the lamp on and off at about 10 0r 15 second intervals. I'll > probably conduct at least part of the test with fiberglass insulation > wrapped around the thermistor to see if that makes any differnece. Well, since Mr. DeArmond has told us in misc.jobs.contract that he is out of work, I suppose he has nothing better to do with his time. I am a little disappointed, though, that Mr. DeArmond cannot think of anything more creative to do than duplicate efforts that others have already done - all to save a few dollars per year. But it makes a Great Tall Tale, doesn't it, Mr. DeArmond? $$> Typical on resistance for the 16 ohm device is 1 ohm which means that it $$> dissipates about a watt with a 100 watt bulb. ... $$> The part will rise $$> about 60 degrees C over ambient when in operation so you don't want $$> to insulate it or pack it in a closed box. The above are quotes from Mr. DeArmond's original article. I'm not always certain what he means by "ambient", but I suspect the above refers to room temperature. But, as readers will see shortly, it doesn't make much difference how his ambient temperature is defined. > > The 16-ohm device is actually a Panasonic (PNT-126), and has a > >maximum rating of 0.6 watts. Its R25/R50 deg C resistance ratio is 2.3, > >which means that its resistance is still about 7 ohms at 50 deg C. I > >would find it difficult to believe that at 85 deg C ("60 degrees C over > >ambient") its resistance would be as little as 1 ohm. 2.5 to 3 ohms > >seems more likely, which means we could be dissipating at least 2.5 > >watts. That's *FOUR* times the *maximum* rating of the thermistor! > > The actual *MEASURED* (as opposed to hypothesized or made up) voltage > drop across a PTN-126 while wired in series with a 100 watt bulb ranges > from 0.8 to 1.0 volts as measured with a Fluke 8800A 5-1/2 digit > voltmeter with the true RMS option installed and an NBS (ne NITS) > traceable calibration. Since the measured current is just a bit under > an amp, the computed resistance is about an ohm and the power > dissipation is about a watt. We know from experience that Larry finds > experimental data "difficult to believe". Fabricated numbers are *SO* > much more tidy. I have 9 pages of detailed specifications on that Panasonic ERT-D thermistor series, and the part claimed by Mr. DeArmond will *not* achieve a resistance of 1 ohm at 85 deg C. The exact part number for the PTN-126 [sic] Digi-Key stock number is the Panasonic ERT-D3FFL160S. Let's first consider its recommended application from the actual Panasonic data sheets: "Temperature detection. Temperature compensation for measuring equipment. Temperature compensation for deflection coil in TV's, etc." Not one word about inrush current limiting. In fact, in the "Precautions for Handling" section Panasonic makes it clear that this part should be used as a measuring component only. Not given in the abbreviated Digi-Key specifications is the dissipation constant of this device: 7 mw/deg C. This means that in order for it to dissipate 1 watt (as claimed by Mr. DeArmond), its temperature would have to rise 143 deg C above 25 deg C, for an actual temperature of 168 deg C. Since the absolute maximum temperature for the device is 125 deg C, it would be destroyed before dissipating 1 watt. Yet, Mr. DeArmond says: "The part will rise about 60 degrees C over ambient when in operation". I believe he means room temperature ambient here, but even if he means fixture ambient, the end result is the same: component failure. I do believe we have, shall we say, "a discrepancy" here. Some possible explanations are: (1) the temperature is really greater than what Mr. DeArmond reported; (2) Mr. DeArmond has made some measurement error; (3) Mr. DeArmond is not using the part number he so claims; (4) Panasonic has lied on their data sheets; or (5) Mr. DeArmond is pulling our leg. Perhaps I am to be so impressed with Mr. DeArmond's claimed use of a 12-year old obsolete 5-1/2 digit DVM with "NBS traceability" that I am to be deterred from further pursuing this issue? But it gets even better in about 22 more lines, so read on... > > Also, the above thermistor series is primarily intended as a > >temperature measuring element, and not for any significant power dissipation > >in any protective circuit. That's why its only rated at 0.6 watts. > > Low ohm negative tempco thermistors with significant watt ratings are > designed for inrush applications and make pretty poor measuring devices, > as a glance at the thermistor curves would show. Oh, so Mr. DeArmond has the curves for this thermistor? If so, then he must notice an amazing degree of parallelism in slopes among the curves for *every* thermistor in this ERT-D-series, from 8 ohms to 150,000 ohms. Since the Panasonic curves are log plots, the lines are almost straight. Low resistance thermistors are indeed used for measuring applications, primarily for temperature compensation. That was a good bluff, Mr. DeArmond - too bad it didn't work. > Since the 600 milliwatt > rating is for worst-case conditions, I have no problem at all operating > the device at higher dissipations under less severe thermal conditions. I have a confession to make: I baited Mr. DeArmond, and he fell for it, shall we say, hook, line and sinker. Call me an SOB if you'd like, but I am really tired of Mr. DeArmond's name-calling and fairy tales. The 600 mw rating is not at all what Mr. DeArmond thinks it is, and I intentionally did not clarify the issue in my original article. Let me quote from the Panasonic data sheets: "Rated power is power that is needed to go up till 125 deg C, and when the ambient temperature exceeds 25 deg C, the rated power should be derated according to the following curve." The curve is a straight line showing 100% at 25 deg C and 0% at 125 deg C. This means that at 125 deg C ambient the thermistor is rated to dissipate *ZERO* power. > We must remember that the ambient temperature in a fixture is MUCH higher > than the 60 degree rise, (80 degree C absolute) measured on the surface > of the thermistor. I'll be generous and say the ambient temperature in Mr. DeArmond's fixture is only 85 deg C. At 85 deg C, the maximum permissible dissipation is 40% of 600 mw, or 240 mw. Oh my, Mr. DeArmond is allegedly running the thermistor at *FOUR* times its rating. Which is exactly what I said in my original article, but I derived the 4-times in an intentionally misleading fashion. I am sorry if I misled anyone else, but my "bottom line" was still correct - and that was the real point. > Since the 600 milliwatt > rating is for worst-case conditions, I have no problem at all operating > the device at higher dissipations under less severe thermal conditions. The truth is, the 600 mw rating is for *best* conditions when the thermistor temperature is heat-sinked at 25 deg C. Less severe thermal conditions, my ass! Maybe this article will cause Mr. DeArmond to grow up and realize that he cannot always bluff his way through life - especially when he pretends to have engineering knowledge that he in fact lacks. In the particular case of this do-it-yourself lamp life extension procedure described by Mr. DeArmond, it disturbed me that he would give bogus advice which has the potential to jeopardize life and property. This is the reason I took some time to research and write this article. The above completes the first half of this article. For those who are solely concerned with technical information, you may stop reading here. For those who would like to see Mr. DeArmond get some well-deserved "attitude adjustment" concerning his Tall Tales, read on. The next part is rather long, and the "revelations" are toward the end, but it should have decent entertainment value to some readers. In article <5265@rsiatl.Dixie.Com>, jgd@Dixie.Com (John G. DeArmond) writes: > Allen, you just gotta overlook Larry the Lid (as he's referred to in other > groups.) I induced him to make an ass out of himself in comp.dcom.telecom > a few months ago and he's been messing his britches to get even ever since. For those readers who are unaware, Mr. DeArmond treated telecom readers to a Tall Tale in which: (1) while working for "the government" at a time when he would have been a teenager; (2) he obtained an electronic eavesdropping device from the CIA; (3) bragged about committing a felony by installing it in his supervisor's office without the benefit of any lawful authority; and (4) used recordings so made to blackmail his supervisor so that the supervisor would not proceed with a plan to have Mr. DeArmond fired by planting marijuana in Mr. DeArmond's car! That's quite a story, huh? Certainly worthy of a few episodes on the former television series "Soap". When I pointed out certain, uh, technical improbabilities in his *detailed* story, Mr. DeArmond got a little upset with me. I wonder why? > He's quite fond of quoting the hypothetical and or calculated answers as > fact. My armchair diagnosis is that Mr. DeArmond appears to disdain what he cannot comprehend, most likely due to feelings of insecurity resulting from his self-admitted lack of a college education (or any other professional credentials, for that matter). More on this shortly from the keyboard of Mr. DeArmond himself. > Just a spoiled rich kid not getting his way. Wrong choice of insult, Mr. DeArmond, as you are about to learn. Funny, but I have never, *ever* mentioned anything on the Net about my finances, employment or standard of living. I do talk about my numerous cats, though. I wonder if that makes me a "spoiled rich kid"? On the other hand, readers of misc.jobs.contract sure have been treated to Tall Tales from Mr. DeArmond about *his* incredible string of financial successes. How about a few choice examples, and then we'll inject some truth? In article <3058@rsiatl.UUCP> jgd@rsiatl.UUCP (John G. DeArmond) writes: $$> I'll use myself and my current team as an example. With only one of us $$> earning less than 100k/yr, I think we could agree that we're more than $$> adequately compensated. The interesting thing is that NONE of us have $$> degrees. I'll be there's not 4 years' college between all of us. I sure believe that last sentence! $$> My slightly younger brother is a dentist. $$> Our earned income is about the same - and remember that I've intentionally $$> backed off a bit for a bit. BUT. He has 8 years of post-secondary $$> education, during which time he did not make a dime. IN fact, he came out $$> of dental school with very large student debt. (and he's one of the few who $$> believes that you really should pay it back.) During that same 8 years, $$> my earnings were in the 7 digit range. Okay, show of hands time: How many other Net readers claim earnings "in the 7 digit range"? Gawd, *SEVEN* digits - why, Mr. DeArmond must be a MILLIONAIRE! And to think he called *me* a "spoiled rich kid"... $$> I'm vastly better educated than most of my peers. $$> The difference is that I made myself become educated rather than relying $$> on an institution to do it for me. I have a library that rivals many $$> small schools. I've read everything in it at least once. Does "read == comprehend"? As my late father was fond of saying about incompetent people: "He woke up one morning, hit himself over the ass with a book, and called himself an engineer." $$> I have a $$> hardware and software development lab that is better than anything any of $$> my clients have. Doesn't say much for the caliber of his "clients", does it? $$> I hope the above did not sound too snobbish. Naw, not at all. $$> But I know of no other way to make the point other than to make an $$> example of myself. Mr. DeArmond certainly has made an example of himself, but not quite in the manner he intended. $$> Of course, one of the best ways to run into degree snobs is to $$> contact a company through their HR slime. Being degree snobs is the only $$> way these people can build any self-respect. One of the reasons why Mr. DeArmond dislikes "HR slime" is because they *verify* resumes, background and credentials - scrutiny which would likely preclude hiring of Mr. DeArmond. More about this later... $$> John De Armond, WD4OQC | $$> Radiation Systems, Inc. | $$> Atlanta, Ga | $$> {emory,uunet}!rsiatl!jgd| In article <3128@rsiatl.UUCP> jgd@rsiatl.UUCP (John G. DeArmond) writes: $$> As a person who has built and sold a large consulting engineering firm $$> in order to return to being small, let me address this point. A "large" consulting engineering firm, no less. Mr. DeArmond always needs to inject that hyperbole. What is the name and location of that firm, pray tell? $$> My personal goal is to do billable work only about $$> 9 months out of the year and spend the rest of the time relaxing/studying/ $$> building new product. I'm just about there. Gawd, I'm turning green with envy. In article <3610@rsiatl.UUCP> jgd@rsiatl.UUCP (John G. DeArmond) writes: $$> Or consider when I was a heavy equipment operator and in the IUOE. $$> I started out running a bulldozer. $$> - a reminder of a much darker period of my career. Oh, so *that's* the kind of "consulting engineering firm" built and sold by Mr. DeArmond, who is now apparently an "operating engineer". Perhaps he consults on how to operate bulldozers? Maybe that's why he doesn't know much about thermistors? In article <3365@rsiatl.UUCP> jgd@rsiatl.UUCP (John G. DeArmond) writes: $$> Let me get this straight. You're advocating that I $$> close down my consulting operation, forgo a 6 $$> digit income and start paying out money to some institution that $$> will after 4 years of hassles give me a sheet of paper? Well, now we're down to a mere "6 digit income"... In article <3578@rsiatl.UUCP> jgd@rsiatl.UUCP (John G. DeArmond) writes: $$> My brother and I have had an $$> informal contest for years to see who makes the most money each year. $$> So far, I've beaten him every year, though the margins are narrowing as I $$> back off from a full 2000 hour work year. Anyone want to give Mr. DeArmond's brother, Eben Jr., a call and ask how the "contest" is going? He practices dentistry in Cleveland, TN. I wonder how Dr. DeArmond would react to his brother posting these, um, "contest results" to the whole world? In article <3610@rsiatl.UUCP> jgd@rsiatl.UUCP (John G. DeArmond) writes: $$> In my past $$> career, I consulted in the nuclear power industry, usually in the $$> field of industrial controls and radiation monitors. How likely is it that a person with an apparent total lack of educational and professional credentials would "consult to the nuclear power industry"? In matters of safety with radiation monitors, no less! Unless, of course, Mr. DeArmond's "consulting" is one reason why the nuclear power industry is presently in trouble. I wonder if he worked at Three Mile Island? In article <3351@rsiatl.UUCP> jgd@rsiatl.UUCP (John G. DeArmond) writes: $$> One of these associations later enabled me to get a half million line of $$> signature credit in order to start my first company. Half a million dollars must have started a pretty large company. I don't suppose Mr. DeArmond would tell us the name and location of that company, eh? Or what happened to it? Mr. DeArmond certainly seems like a very rich and successful person. One would think that a person with "7 digit earnings" would live in some storybook Southern mansion replete with antebellum splendor. Especially a fellow like Mr. DeArmond, who obviously likes to show off and is *very* proud of his alleged income and success. Curiously, however, that does not appear to be the case. Sources in Marietta, GA say that Mr. DeArmond and his wife Doreen live in a rather non-descript one-story 2,051 sq-ft house on a 4,089 sq-ft lot with an improved value of $ 76,936.00. Where, pray tell, are the fruits of Mr. DeArmond's "7 digit earnings", since they certainly don't appear to be in his house? They don't appear to be in the cars he drives, either. Could all his income be tied up maintaining NBS-traceability for a 12-year old obsolete FLUKE 8800A 5-1/2 digit DVM? How can Mr. DeArmond reconcile this curious situation? Lemme guess: perhaps he'll say it's just the servants' quarters and he really lives elsewhere! In article <3488@rsiatl.UUCP> jgd@rsiatl.UUCP (John G. DeArmond) writes: $$> Anyway, I thought I'd offer some experiences regarding working at home. $$> RSI is based in my basement. I've converted the entire 2500 sq ft $$> basement into an office and laboratory. Good lord, Mr DeArmond even exaggerates the size of his basement! Can't he tell the plain truth about *anything*? But wait, maybe the extra 25% is located in an underground bunker, the existence of which is unknown to the Cobb County Board of Assessors. That's right, that's the ticket! I will give an even better example of Mr. DeArmond's veracity. In article <4976@rsiatl.UUCP> jgd@rsiatl.UUCP (John G. DeArmond) writes: $$> Never use the title of President except where you legally $$> must. I use the title "General Manager" or "Director of Engineering" $$> depending on who I am addressing. This implies a larger organization $$> ... $$> I've had many clients in the last 10 years $$> but only one employer - my company, Radiation Systems, Inc. My resume $$> reflects that fact. This approach gets around the pinheaded personnel $$> people plus it demonstrates to your prospective sponsor a degree of $$> stability and success. It's all a matter of perspective. Here's the truth, as furnished by a recipient of one of Mr. DeArmond's "resumes" who had the truly bad manners to actually check it out: Radiation Systems, Inc. was incorporated in the State of Tennessee on 2/28/85 listing Mr. DeArmond as registered agent with a home address on Talley St. in Cleveland, TN, and with a corporate address of his father's (Eben DeArmond, Sr.) accounting business office on Broad St. Now, here's the real kicker - on 3/31/89 the Tenessee Secretary of State revoked the corporate charter of Radiation Systems, Inc. for failure to file corporate reports and tax returns since 1987! While Mr. DeArmond now lives in Marietta, GA, his corporation was never incorporated or registered as a foreign corporation in the State of Georgia, either. One would think Mr. DeArmond's "CPA" or "corporate attorney" (as he is fond of referring to in misc.jobs.contract when dispenses allegedly sage advice) would see that he uses a corporate identity in a lawful manner, huh? Or is Radiation Systems, Inc. apparently just another one of Mr. DeArmond's failures? Incur some debts in the name of a corporation, screw the creditors and let it go defunct, perhaps? Maybe botch some work, get sued by unhappy clients and just run away? Oh well, so much for "10 years with one employer" and truthfulness on a resume... In fact, so much for being truthful to Net readers, too! Perhaps Mr. DeArmond could also tell us why *suddenly*, three or so weeks ago he finally stopped using the name Radiation Systems, Inc.? Someone catch up with you, Mr. DeArmond? The IRS, perhaps? The IRS is on the Net, btw, (check the DC map file), and I bet they could have a field day with Mr. DeArmond's "7 digit earnings" and solicitation of business (over the Net, too!) using a defunct corporation name. In closing, here are a few more assorted gems: In article <4164@rsiatl.UUCP> jgd@rsiatl.UUCP (John G. DeArmond) writes: $$> Yes, Yes, and Yes. In my case, even though the company has existed $$> for almost 10 years, I have a multi-hundred thousand dollar line $$> of unsecured credit and my record is absolutely spotless, we almost $$> did not get a loan on our last house. We ended up putting down $$> 25% which entitles you to a "No-docs" or no credit check loan. The above seem a little funny to any reader? I certainly believe the part about paying extra money to avoid the embarrassment of failing to pass a credit check, though! $$> Disclaimer for the knuckleheads out there: No, I do not advocate lying $$> or even distorting the truth. Naw, never - eh, Mr. DeArmond? In article <3132@rsiatl.UUCP> jgd@rsiatl.UUCP (John G. DeArmond) writes: $$> Reality is starkly different. Over the last 5 years or so, I've $$> written off about $50,000 in bad debt losses and have paid about $$> another $30k in legal fees prosecuting collections. The scars are $$> just now going away. I've NEVER lost a collection suit and I've $$> never collected any significant amount of money! I genuinely believe that Mr. DeArmond lost money and incurred legal fees, but perhaps for some slightly "different" reasons. In article <3204@rsiatl.UUCP> jgd@rsiatl.UUCP (John G. DeArmond) writes: $$> Just as we were turning up the first system, the founders of this $$> startup phone company sold the company. The new owner was, shall $$> we say, unsavory. He decided that he did not want to pay royalities $$> or allow us to own the program -which we had the right to. So he $$> addressed the problem in the usual mob manner - he sent some goons over $$> to kidnap us while they stole our equipment and software. $$> ... $$> Sure we sued them and pressed criminal charges. But in America today, $$> money is justice (and don't ever forget that.) He managed to have the $$> criminal charges quietly dropped and the civil case, though still $$> technically on the docket now 5 years later, is effectively dead. Lordy, what a *story*! KIDNAPPED BY GOONS FROM THE MOB! And Mr. DeArmond wants us to believe his claim about testing the thermistors!? Larry Lippman @ Recognition Research Corp. "Have you hugged your cat today?" VOICE: 716/688-1231 {boulder, rutgers, watmath}!ub!kitty!larry FAX: 716/741-9635 {utzoo, uunet}!/ \aerion!larry
amichiel@rodan.acs.syr.edu (Allen J Michielsen) (12/16/90)
In article <6223@videovax.tv.tek.com> bill@videovax.tv.tek.com (William >In article <1990Dec13.172348.20146@amd.com> phil@brahms.amd.com (Phil Ngai) >>In article <4078@osc.COM> jgk@osc.COM (Joe Keane) writes: >>I can not see any reason to use incandescents anymore, unless you >>are getting free power. >Of less importance is you lose dimming with fluorescent.(I can live without >This is unfortunate. I'd love to change all my lights to fluorescent, O.K. Here goes, engage your total recall circuits... Your going laugh yourself silly, call the kids to the monitor & wake the neighbors, but just remember in 30 years you heard it here (and by ME) first. There are several (either) obscure (or obscured) studies regarding visual UV wavelength exposure (i.e. fluorescents in a office environment) over long periods (like those of a average office worker), and resulting long term visual damage. The range is great, but at min is greatly reduced night vision (inclusive of both visual acquitt & adjustment time) and at the other end is increased risks of 'stuff' like catarats. One study even went on to try to find a vitiman enhancement program to reduce the damage. I'll be the first to admit that these studies weren't perfect, and that there are many problems involved coming up with a really 'fair' method of comparing and isolating office workers with & without flurescents without comparing office workers and sheep herders, but believe that time will tell. And that eventually UV filters (of some kind) will be on all fluorescent lights. Untill then, I'll not be using anymore fluorescents in my home than I really must. If you look at what you spend on actual home lighting in so far as KWH's and the saving using Fluorescents (even if you want to ignore the difference in cost per bulb &/or cost per fixture &/or hardware cost/lumen hour), in a typical house, the $$$ savings is less than is worth considering. I'd wager that you spend more on tips for meals than you'd save in a year. Even when the cost per KWH increases 500%, your income will also increase, and this relationship will remain about the same (of course we'll have to wait & see, but...). al -- Al. Michielsen, Mechanical & Aerospace Engineering, Syracuse University InterNet: amichiel@rodan.acs.syr.edu amichiel@sunrise.acs.syr.edu Bitnet: AMICHIEL@SUNRISE
jgd@Dixie.Com (John G. DeArmond) (12/16/90)
We all got to see another one of Larry's little mental explosions. Larry's obsession with my life has obviously become an illness. It is unfortunate that such people are allowed about. Nontheless they are so we have to live with it. I won't bore the group with a a point by point rebuttal. I will address only the technical issues the Lid raised and then opinionate only a bit at the end. [An amazing and most likely fabricated investigative quest description deleted.] > Likewise, I had not previously heard of any fires caused by the >UL-approved devices, which is why in my original article I stated that UL >considered them safe because they were confined within the metal barrier >of the lamp socket. I never claimed that the rectifier buttons had caused any fires and I don't believe the other fellow did either; I simply stated that the ones I tried in my fixtures had burned to a crisp. Since there was nothing flammable near the socket other than the lining of the socket itself, it would be hard to imagine a fire scenario. *BUT*, the fact that the buttons burned up - I did save the residue to show people - tells *ME* that there is a potential to start fires. And to that conclusion, I don't give a damn WHAT UL has to say about it. > It may also help readers to know that typical base temperatures >of incandescent lamps in the range of 60 to 100 watts run from 194 to >208 deg F (data taken from NFPA handbook). As usual, Larry backs up his arguments with rote dissertations from a book. Since "typical" rarely occurs outside the printed page, I prefer to make in situ measurements of the actual conditions involved. I'll allow the reader to determine whether "typical" values from a text or measured values are more appropriate in a given situation. > What Mr. DeArmond failed to find in his Digi-Key catalog, because >it was somewhat buried at the upper right hand corner of a page which >otherwise listed varistors, was the one series which actually is suitable >for power inrush limiting. Those thermistors, the Keystone CL-series, >have 18 AWG and 22 AWG wire leads, are quite suitable for lamp or power >applications, and have explicitly specified current ratings from 1.1 to >12 amps. The best part is that at full rated current THEY DON'T GET ANY >HOTTER THAN 25 DEG C. Yes, the Keystone parts are quite adequate, but the panasonic ones are too. I'm not arguing against the Keystone or any other similiar part, I'm arguing based on actual experimental results that the Panasonic part works quite well. I was originally attracted to the 8 ohm part as a result of seeing it used in an inrush application. >He'll just tell >the insurance company that he made measurements with a gen-U-wine >FLUKE 8800A 5-1/2 digit DVM, that while 12 years old and obsolete, >still has NBS-traceable calibration! :-) Is the implication here that one should discard fully functioning instrumentation that meets the manufactur's specifications and has a traceable calibration just because it accumulates some age? Is that what you're really trying to say, Larry? Or are you saying that new is better regardless of its calibration? Do you think that a voltage measurement made to 4 decimal places with an instrument that is within mfr's specifications is bogus because the instrument is old? I would have expected much better for someone who purports to be technical. > A filament short is *usually* blown away because there is no >device in series with the lamp to create impedance and limit current. >A series thermistor, even in the hot state, may well limit current such >that neither the shorted filament nor thermistor itself will have >enough energy to instantaneously open. The actual instantaneous >fault current available from a typical 20 ampere electrical branch >circuit may reach the hundreds of ampere range, with a low resistance >fault within a lamp usually blowing out in several cycles - which is >usually not long enough to trip an overcurrent device. It doesn't take >much imagination to see how even 1 ohm of series resistance can drastically >reduce current such that the energy necessary to open an internal lamp >fault is no longer available. But if your imagination is true, then any lighting circuit that contains a dimmer circuit is a fire hazard. After all, dimmers contain active devices with no more physical ruggedness or surge handling capability than the thermistor in question. Let's look at a hard example. I pulled the dimmer from a fixture in my house and looked at it. It contains a device that cross references to a GE SC-146 triac that is packaged in a TO-220 package. The GE SCR manual rates this device at 10 amps continuous. The dimmer is a 1000 watt unit which is larger than the normal 600 watt units which would probably use the equivalent of a GE SC-241. The data sheet gives a maximum peak one cycle non-rep surge current of 100 amps. In other words, this is the maximum current the device would be expected to handle for one cycle of AC current in isolation from all others. This is the value used to evaluate triacs for inrush and filament short circuit duty. On page 245 of the same manual, it recommends that for a 100 watt bulb, the inrush current design criteria be abtou 17 amps. Thus this triac gives very good margins for inrush but it would fail miserably in Larry's direct short, multi-hundred amp scenario. But the failure rate for lamp dimmers is insignificant. What's wrong with this picture? Could it be that Larry's scenario is incredable? I think so. If we saw any significant instances of long term (defined as many cycles) direct short circuits, the fatality rate for lamp dimmers would probably get the attention of Ralph Nader :-) It would be reasonable to postulate that the vast majority of lamp failures involve filament short currents of less than about a hundred amps for only a cycle or two. > Consider this example, which should be intuitive to many readers. >A 2" piece of 28 AWG wire connected to the 18 AWG conductors of a line cord >will probably blow away in a fraction of a second if the line cord were >plugged into an AC outlet. If an appropriate series impedance that limited >current were now added to the circuit, the 28 AWG wire would first become >red hot (perhaps for a long time) before opening. Also, that series >impedance might itself get rather hot in the process. After thinking about it for a minute, I decided to make another test. I took a PNT-124 8 ohm thermister out to my metal shop and connected it to my DC welder power supply. A Gen-U-wine Fluke amp-clamp was applied to the secondary lead before the rectifier in order to measure the peak current. The volt meter in this case was an IES 2360 (brand new but uncertified - that ought to make the Lid happy :-) because it has a peak hold feature. The thermister was clamped directly between the two welding clamps so as to reduce the circuit impedance. I set the welder control to 150 amps and pushed the ON button... The thermister "flashed" into oblivion. "Flashed" is the best word to describe the action. There was a brief ball of flame similiar to that from the muzzle of a gun. The device pretty much disapeared. The leads were left clamped into the welding clamps. The tinplate on the leads was slightly discolored but not so much as to expect it got red hot. The interesting thing is that there are still shards of solder on the end where the thermistor used to be. That would explain the flash. The solder attachment points failed and vaporized in a ball of fire. The peak current registered was about 230 amps. I say "about" because I don't know the single cycle behavior of this meter and because it is not certified. I'll let the reader determine if this failure mode, which is similiar to many solid state components when grossly overloaded, is hazardous in the context of a lamp socket. I do agree that in the event a person were to place sufficient impedance in a lamp circuit such that the current could only peak at 20 amps or so, that it would be a bad idea to use ANY thermistor in the circuit. >> and because we could speculate that a lamp construction that would allow >> a continuous short between electrodes could never be approved, > > Mr. DeArmond should take apart a few different models of light >bulbs and see how filament support wires can well be deflected against >broken filament sections to create low resistance faults in a lamp failure. >Such light bulbs are all UL-approved. As usual, Larry did not address the issue. A connection established across part of a filament merely establishes a circuit through a filament that is now grossly overvoltaged. This filamnet will fail instaneously and with quite a show of pyrotechnics. Let's assume that a filament could establish contact with the opposite electrode over as little as a fourth of its length. That would mean that its cold resistance would be 1/4 that of normal and the inrush would be 4 times normal. Using GE's figure of 17 amps for a 100 watt bulb, that would give us an inrush of 68 amps. This is still well below the point that even the triac discussed above would fail, assuming the filament blew away in one or two cycles. Since the filament would heat vastly more rapidly than normal, the failure would clear the fault more rapidly than the normal inrush interval. From the discussions in the GE SCR manual, planning on filament clearance times of one or two cycles is reasonable. > Yet, Mr. DeArmond says: "The part will rise about 60 degrees C >over ambient when in operation". I believe he means room temperature >ambient here, but even if he means fixture ambient, the end result is >the same: component failure. And yet they don't fail. Is it magic? I think not. It is the result of careful experimentation and design. Learn how to read a spec sheet, Larry, and then do some experimental work to verify the applicability of the datasheet. Learn what the term "specsmanship" means. Be creative and never take a spec sheet at face value. You might slip up and find a use for something that the manufacturer never imagined. [another mental masturbation deleted.] > The truth is, the 600 mw rating is for *best* conditions when >the thermistor temperature is heat-sinked at 25 deg C. Less severe thermal >conditions, my ass! Maybe this article will cause Mr. DeArmond to grow up >and realize that he cannot always bluff his way through life - especially >when he pretends to have engineering knowledge that he in fact lacks. If you think my data is so bogus Larry, why don't you simply repeat the tests. If you've got enough time to prowl around in my personal life, you've obviously got enough time to set up a light bulb and a digital pryometer and report your own results. We know why you don't, of course. You'd rather masturbate in public and sling mud. There's some growing up to be done but it's not on this end. Tell you what, guy. Why don't we just cut to the chase and be done with it. I'll put my experimental results up for 3rd party verification and make the results available here. Let's see if you've got the guts to duplicate the experiments and do the same. I'll even let you use a NEW voltmeter. ----------------- EDITORIAL OPINION What follows is strictly my opinion. If you don't want to read further, go to the next article. Let's look at the extremes to which Larry has gone in order to satisfy his fettish. He has bought a CD ROM version of the net at no small cost in order to be able to conduct his hate-driven vendetta against me and a couple of others on the net. That in itself is sick. But he goes further. He posts "facts" about my personal life that are just plain out and out lies. Everything from the trivial such as the size of my house and office and what I paid for it to the rather serious such as slandering my company, my financial status and my family. Did you know, for example, that I've gotten reports of his contacting former clients and spewing this filth? It is probably a waste of time to even attempt to address these lies so I won't. But if anyone has questions about a particular instance, please email and we'll discuss it. I suppose it is to be expected that successful people make a few enemies. There are people in this world who are so insecure that they terribly resent others who have bootstrapped themselves up under adverse conditions. They like to rationalize others' successes and their failures with excuses like "If only I had as much {money, education, good looks, balls, etc} as that guy, I'd be successful too". They tend to view others through the distortions of their own character flaws. Thus with Larry. The only thing he has achieved in his life is having Daddy put him through college so he terribly resents those successful people who did not do so. I quite possibly would be more successful than I am now with a full college education but we'll never know. At least I'm honest enough to admit my lack of that credential. One does, however have to wonder about an obcession with something that in my case would have happened almost 20 years ago. When I would have been in college, the 8008 would have been the rage :-) Isn't that scary. I wonder how relevant that education would be today? Perhaps I should get mad and get a lawyer or worse. Maybe I will before it's over. I'll admit that I did get mad several months ago in the beginning of his fit. Normal people just don't act like Larry does so he caught me off guard. But what I feel right now is pity. Pity for a person with such a distorted phyche that he must try to build self-respect by attacking others. I'd imagine that he feels terrible guilt from having had it all given to him by Daddy and anger because he cannot find a way to enjoy it. Daddy was probably authoritarian and this is Larry's way of striking back. I initially wondered what it could have been that sent him off into such a frenzied rage starting over in comp.dcom.telecom a few months ago. I'd never had a conversation, email, net or otherwise with the guy. What I discovered as I began to swap email with other of Larry's victims is this model of his personality that I've described here. The really sad part is that he could probably build that self-respect AND the respect of others strictly on his own. Perhaps it's not too late. Larry, I do hope you get help with your problem. You'll live a much happier life for it. We'll be rooting for you. John -- John De Armond, WD4OQC | "Purveyors of speed to the Trade" (tm) Rapid Deployment System, Inc. | Home of the Nidgets (tm) Marietta, Ga | {emory,uunet}!rsiatl!jgd | "Vote early, Vote often"
bwhite@oucsace.cs.OHIOU.EDU (Bill White) (12/16/90)
In article <4247@kitty.UUCP> larry@kitty.UUCP (Larry Lippman) writes: [For reference here, my first experience with Larry was on sci.chem and it was less than pleasant. He basically told me I didn't know what I was doing when I wanted to do a decades-old synthesis of dyes. He was also correct, I didn't -- I checked up on what he said, and found out that my information was outdated and dangerous and that I had nowhere near the knowledge I needed to do what I wanted to do. Since then I've been following Larry's articles in sci.chem and in sci.electronics. A few references he gave in sci.electronics I looked up at first -- and found them to be correct. Larry is one of the few posters I have known to be accurate, which to me counts more than just about anything else. Frankly, I haven't been following this thread much; however I did happen to read this article, and the one it refers to. For reference, I'm an undergrad, one of my majors is electronics. I don't have a degree and don't claim to. Like many other people, I got an early start into electronics via ham radio and because my next-door neighbor is an electrical engineer who works at the Perry Nuclear Power Plant in Cuyahoga County, OH. When I visited Perry I talked to one of their engineers about the companies they contract with. From what he told me, I am convinced that DeArmond's company wouldn't have a chance. They do all their homework -- even for supposedly "minor" jobs that someone like me could do -- because the consequences of failure could be extreme. Oh yes -- I've also had some experience with electrical (as opposed to electronics) work -- in fact I'm going up for certification as an electrician next quarter. I can tell you that modifying a lamp (or any other piece of electrical equipment not meant to be modified) is not looked upon well by insurance companies, and for good reason. I've seen a lot of really bad home-modifications (to say nothing of botched attempts at wiring, such as one bozo who switched the neutral and ground on an outlet, and wondered why nothing in that outlet worked right). Even as simple and "innocent" a thing as putting a three-to-two prong converter onto a three-prong plug can be a hazard. How many people take the time to ground the converter by screwing the lug into the outlet (if the box is grounded) or another acceptible ground? I apologize for taking up so much bandwidth, but I just wanted to say that in general I find Larry's articles to be correct. Keep in mind, though, that one should check out any information before doing something that could be a fire or safety hazard.] > Okay, show of hands time: How many other Net readers claim earnings >"in the 7 digit range"? Gawd, *SEVEN* digits - why, Mr. DeArmond must be a >MILLIONAIRE! And to think he called *me* a "spoiled rich kid"... But Larry, you forgot to take into account leading zeros and decimal points! >Larry Lippman @ Recognition Research Corp. "Have you hugged your cat today?" >VOICE: 716/688-1231 {boulder, rutgers, watmath}!ub!kitty!larry >FAX: 716/741-9635 {utzoo, uunet}!/ \aerion!larry -- | Bill White Internet: bwhite@oucsace.cs.ohiou.edu | | ANTHONY'S LAW OF FORCE: | | Don't force it, get a bigger hammer. |
sjb@dalek.UUCP (Seth J. Bradley) (12/17/90)
In article <5297@rsiatl.Dixie.Com> jgd@Dixie.Com (John G. DeArmond) writes: >I never claimed that the rectifier buttons had caused any fires and I >don't believe the other fellow did either; I simply stated that the ones >I tried in my fixtures had burned to a crisp. Just to add another data point, two of the diode buttons I tried also burned up (though 6 others worked fine for years). On one lamp I tried putting a 3 amp 400 PIV diode in series in the lamp's cord (this was a lamp which was on most of the time and which one of the buttons had burned up on). I know that this would not be UL approved, but is it inherently unsafe? -- Seth J. Bradley Address: sjb@dalek.iwarp.intel.com Or: dalek.UUCP!sjb
larry@kitty.UUCP (Larry Lippman) (12/17/90)
In article <5297@rsiatl.Dixie.Com>, jgd@Dixie.Com (John G. DeArmond) writes: I will make this as brief as possible, and leave it up to readers to draw their own conclusions. I urge any interested readers to carefully re-read my previous article and compare it to Mr. DeArmond's response. Note the numerous items he failed to respond to, and note what tangents he created to avoid the central issues. Note how he avoided comment on the issue of how a lamp fixture modification can void an insurance policy - which was probably the single most important point that I was trying to convey! > [An amazing and most likely fabricated investigative quest description > deleted.] Amazing indeed, but not exactly fabricated. As an example, for the small price of a short telephone call any reader wishing to verify certain facts that I presented may contact the Tennessee Secretary of State (615/741-2816) and the Georgia Secretary of State (404/656-2817), both agencies being more than willing to furnish information over the telephone. While at first glance perhaps being irrelevant, the simple point made in the second portion of my previous article is that a person making egregious misrepresentations on one topic, as I have *proven* in the case of Mr. DeArmond, is likely to make misrepresentations on *any* topic. > I never claimed that the rectifier buttons had caused any fires and I > don't believe the other fellow did either Mr. DeArmond seems to have a short memory: $$> amichiel@rodan.acs.syr.edu (Allen J Michielsen) writes: $$> > The funny part here is that while ul listed, these button type jobs are $$> >a common cause of fires, and very popular (winning) lawsuit item. $$> By the time they had failed and shorted under $$> 100 watt bulbs, they had emitted a large quantity of smoke and had $$> fried to a blakened crisp. *I* consider them a fire hazard after my $$> experience. > > It may also help readers to know that typical base temperatures > >of incandescent lamps in the range of 60 to 100 watts run from 194 to > >208 deg F (data taken from NFPA handbook). > > As usual, Larry backs up his arguments with rote dissertations from a > book. Since "typical" rarely occurs outside the printed page, I prefer > to make in situ measurements of the actual conditions involved. I'll > allow the reader to determine whether "typical" values from a text or > measured values are more appropriate in a given situation. Apparently Mr. DeArmond has never encountered the concepts of sampling, variance, distributions and statistics. So, Mr. DeArmond claims to have made perhaps *one* measurement on *one* light bulb, and now he knows more accurate information than the NFPA! Poor Mr. DeArmond! - he cannot appreciate the humor of his own naivete. > > What Mr. DeArmond failed to find in his Digi-Key catalog, because > >it was somewhat buried at the upper right hand corner of a page which > >otherwise listed varistors, was the one series which actually is suitable > >for power inrush limiting. Those thermistors, the Keystone CL-series, > >have 18 AWG and 22 AWG wire leads, are quite suitable for lamp or power > >applications, and have explicitly specified current ratings from 1.1 to > >12 amps. The best part is that at full rated current THEY DON'T GET ANY > >HOTTER THAN 25 DEG C. > > Yes, the Keystone parts are quite adequate, but the panasonic ones are > too. I'm not arguing against the Keystone or any other similiar part, > I'm arguing based on actual experimental results that the Panasonic part > works quite well. The two components cost about the same money, the Keystone part is specifically designed for the application, and the Keystone part gets no hotter than ambient temperature. The Panasonic part is not recommended for the application, Mr. DeArmond admits that it rises in temperature by 60 deg C above ambient, Mr. DeArmond is operating it at least 400% above its rating, and he concludes "it works quite well"! Not to mention the other issues raised in my previous article... > Let's look at a hard example. I pulled the dimmer from a fixture in my > house and looked at it. [nonsense deleted] I won't play Mr. DeArmond's game and get off on a tangent. It seems that Mr. DeArmond would like to forget the real issues: 1. Is modification of wiring in a light fixture, per Mr. DeArmond's suggestion, a building code violation, and can it void insurance coverage in the event of a fire? 2. Is Mr. DeArmond's suggestion a potentially dangerous misapplication of a thermistor? 3. Did Mr. DeArmond tell us a bogus story about his "test results", in view of the actual specifications of the device in question?? > After thinking about it for a minute, I decided to make another test. > I took a PNT-124 8 ohm thermister out to my metal shop and connected > it to my DC welder power supply. [more nonsense deleted] My gawd, another tangent - allegedly testing the thermistor on a DC welder, no less! Does Mr. DeArmond think that if he wastes enough lines on enough tangents that readers will tire and forget the real issues? > > Yet, Mr. DeArmond says: "The part will rise about 60 degrees C > >over ambient when in operation". I believe he means room temperature > >ambient here, but even if he means fixture ambient, the end result is > >the same: component failure. > > And yet they don't fail. Is it magic? I think not. It is the result > of careful experimentation and design. Learn how to read a spec sheet, > Larry, and then do some experimental work to verify the applicability of > the datasheet. Learn what the term "specsmanship" means. Be creative > and never take a spec sheet at face value. You might slip up and > find a use for something that the manufacturer never imagined. Mr. DeArmond's argument is absurd beyond belief. When a real engineer specifies say, a 1 watt resistor, is an actual application likely to require dissipation of 0.75 watts or 4.0 watts? If we are to take Mr. DeArmond's advice, we should exceed all ratings by at least 400%, or until slightly less than failure conditions - whichever comes first! > If you think my data is so bogus Larry, why don't you simply repeat the > tests. I did. Mr. DeArmond had the misfortune of picking a thermistor vendor and series which I use, I have experience with, I have extensive data on, and which I have extensive inventory of. But don't any reader take my word for this - just call Panasonic and ask to speak with an application engineer. Panasonic ought to know their own components better than anyone else! Also, if a reader really wants to know about the Panasonic thermistor specifications, I will be glad to fax them the 9 pages of data which are applicable (provided that I don't get inundated with requests; this offer does not apply to Mr. DeArmond or a shill in his behalf). > We know why you don't, of course. You guessed wrong, Mr. DeArmond. I do my "homework". > Tell you what, guy. Why don't we just cut to the chase and be done > with it. I'll put my experimental results up for 3rd party verification > and make the results available here. Human nature being what it is, Mr. DeArmond knows that no one will actually go to that much trouble since it would require considerable time, communication and coordination among various people. So, Mr. DeArmond bluffs and hopes to plant a seed of doubt. What *else* can a person with Mr. DeArmond's ego do? Actually admit he told a Tall Tale? However, in the beginning of this article I made it easy for a reader to ascertain Mr. DeArmond's veracity in a 5-minute telephone call. Now *that* is something a curious reader may actually do. Any takers? [refer back to my previous article for details to be verified]. > What follows is strictly my opinion. If you don't want to read further, > go to the next article. A two-section article. Just like mine. I'm truly honored that Mr. DeArmond wishes to emulate my writing style. > It is probably a waste of time to even attempt > to address these lies so I won't. Mr. DeArmond cannot very well refute the *truth*. Some of those "lies" were pretty serious, if they were in fact "lies". One might think that Mr. DeArmond would refute just one "lie", though, to prove his point. > I suppose it is to be expected that successful people make a few enemies. > There are people in this world who are so insecure that they terribly > resent others who have bootstrapped themselves up under adverse > conditions. You're right, Mr. DeArmond - I am envious of your "7 digit" income and all of your "trappings of success", especially the 500 sq-ft underground bunker in your house. :-) > At least I'm honest enough to admit my lack of that credential. It has only been since the formation of misc.jobs.contract that Mr. DeArmond has admitted his lack of education and credentials - so that he could regale readers in that group with his allegedly vast self-made business successes. In various prior articles, however, Mr. DeArmond has claimed to be a "health physicist", and has dispensed advice about radiation safety issues. Nothing like a self-taught "health physicist"! Sort of like a self-taught "brain surgeon", if anyone fails to get the point. > Perhaps I should get mad and get a lawyer or worse. Maybe I will before > it's over. Please do that, Mr. DeArmond. I *love* to testify in court, and so far I have a 1000 batting average: no client for whom I have testified as an expert witness in product liability and forensic science matters has ever failed to win their case or otherwise obtain a favorable out of court settlement. Also, I freely admit that testifying as an expert witness is the *ultimate* "ego trip", and it's also the ultimate mind game when the defense tries to pick apart one's testimony. Will this be your "corporate attorney" you always refer to in misc.jobs.contract? You know, the attorney who apparently must tell you it's okay to not file your state corporation reports and tax returns so that the state revokes the charter of your corporation, and that it's okay to operate using a defunct corporation name. > What I > discovered as I began to swap email with other of Larry's victims is this > model of his personality that I've described here. By all means, I encourage my other "victims" to come forward and denounce me and my "lies"! > Larry, I do hope you get help with your problem. You'll live a much > happier life for it. We'll be rooting for you. Mr. DeArmond is right, I have a problem: I dislike liars and braggarts, especially those who give advice that if actually followed could result in harm to others. Larry Lippman @ Recognition Research Corp. "Have you hugged your cat today?" VOICE: 716/688-1231 {boulder, rutgers, watmath}!ub!kitty!larry FAX: 716/741-9635 {utzoo, uunet}!/ \aerion!larry
phil@brahms.amd.com (Phil Ngai) (12/17/90)
In article <6223@videovax.tv.tek.com> bill@videovax.tv.tek.com (William K. McFadden) writes: |Because X-10 fluorescent wall switches cost 5X as much as incandescent. |In addition, the fluorescent X-10 switch requires a neutral lead Do compact fluorescents such as the Philips SL*18 require all this? (you can get them from "Real Goods" if your local stores don't have them) --
larry@kitty.UUCP (Larry Lippman) (12/17/90)
In article <160@dalek.UUCP>, sjb@dalek.UUCP (Seth J. Bradley) writes: > Just to add another data point, two of the diode buttons I tried > also burned up (though 6 others worked fine for years). If people are experiencing failures where these lamp extender buttons are burning up, then *please* report this to various appropriate organizations - which are *not* aware of this being any serious problem! I have listed telephone numbers and contact persons in my previous article. Also, under the circumstances, I will disclose the name of the engineer I spoke with at UL: Bruce Bohren. Please bear in mind that for your report to be useful, you *must* provide some vendor or manufacturer identification for the device that has failed. > On one > lamp I tried putting a 3 amp 400 PIV diode in series in the lamp's > cord (this was a lamp which was on most of the time and which one > of the buttons had burned up on). I know that this would not be > UL approved, but is it inherently unsafe? Lighting appliances which are "portable", i.e., which have a cord and plug and not permanently attached to a structure, are generally exempt from electrical inspection requirements. The use of a non-UL approved device in such an application is far less serious (from a regulatory and insurance standpoint) than modification of permanently-wired lighting fixtures as advocated by Mr. DeArmond. This does not mean that modification of a table lamp that voids UL approval is any less of a fire hazard, it just means that it is probably not a local building code violation. The addition of a 2 amp fuse (say, wire lead type) to the 3 amp 400 PIV rectifier would make such a modification "reasonably safe". Such components should be enclosed in flame-retardant insulating sleeving (readily available), and installed so that: (1) the insulation will permit heat dissipation of the forward voltage drop of the diode times the RMS current under maximum load; (2) the fuse and diode will not be subject to any mechanical wear and tear; and (3) the fuse and diode cannot come in contact with any exposed metal portions of the lighting appliance. I do *NOT* recommend that you make the above modifcations, but if you are bound and determined to do so, at least consider the above guidelines. I would suggest that instead you consider rough duty or 130 volt lamps. Larry Lippman @ Recognition Research Corp. "Have you hugged your cat today?" VOICE: 716/688-1231 {boulder, rutgers, watmath}!ub!kitty!larry FAX: 716/741-9635 {utzoo, uunet}!/ \aerion!larry
charless@cory.Berkeley.EDU (Charles R. Sullivan) (12/18/90)
In article <schumach.661141590@convex.convex.com> schumach@convex.com (Richard A. Schumacher) writes: >Okay, several people have stated that in-rush (high >initial current) reduces an incandescent's life. How? >What's the mechanism? Before I describe failure on turn-on, let me describe 'normal' end-of-life. It's got an interesting wrinkle: A perfect filament would gradually evaporate, equally from all points on its surface. Thus it would get thinner, and the resistance would go up. When it got to be a higher resistance it would run cooler, and evaporate more slowly. Because the evaporation is exponential with temperature, it would never evaporate completely, but just gradually get dimmer. In real life, the filament has some defects--spots that are a bit thinner than the rest of the filament. These have the same current as the rest of the filament, but higher resistance (per length). So they run hotter. This makes the tungsten evaporate faster, which makes the spot get even narrower, which makes it run hotter (it is still only a small fraction of the total resistance, so the current is constant.), and so on....until that spot breaks. ( a good reason not to buy low-quality bulbs) Now consider start-up. The cold resistance of the tungsten is ~10x less than hot. (mesure a light bulb with an ohmmeter and calculate 120^2/R. It will be ~10x the rated watts). So at turn-on you get a big current until the filament has heated up (actually only ~10 cycles of 60 Hz). The defect spots will not only be heated up more by having a high resistance, but they will also get heated up faster, because they have less thermal mass (actually thermal mass to surface area ratio is what matters). This fast heating continues not until the hot spots reach their operating temperature, but until the rest of the filament reaches its operating temperature. (Remember, the rest of it has most of the resistance, and so controls the current.) Thus the hots spots will overshoot their steady-state operating temperature, which is already hotter than the proper operating temperature. This overshoot is only for ~1/6 second, so the extra evaporation during the overshoot is not significant for accelerating the aging of the bulb. But if the bulb is very close to failure, and the hot spots are really bad, they can overshoot to the point where the tungsten softens or melts, and the filament can break. Hence my assertion that the only time a soft start would help was when the bulb was close to failure anyway. The above qualitative argument doesn't give a number for what 'close to failure' is. If it were, say 300 Hrs., that would be significant, but my understanding is that it is something less than about 8 hours, so it doesn't make much difference in bulb life. Thus the only difference the soft start feature of 'life extenders' makes is that now your reading light will quit after you are settled into your armchair with a book, instead of when you first turn on the light. (The voltage drop across the extender during normal operation does extend the lamp life significantly, but with an even more significant waste of energy.) If you get a compact fluorescent, it won't fail when you turn it on *or* after you sit down! :-) (until much later, >~10x life of an incandescant). Charlie Sullivan charless@cory.Berkeley.EDU
bill@videovax.tv.tek.com (William K. McFadden) (12/19/90)
In article <1990Dec17.035646.4694@amd.com> phil@brahms.amd.com (Phil Ngai) writes: ->In article <6223@videovax.tv.tek.com> bill@videovax.tv.tek.com (William K. McFadden) writes: ->|Because X-10 fluorescent wall switches cost 5X as much as incandescent. ->|In addition, the fluorescent X-10 switch requires a neutral lead -> ->Do compact fluorescents such as the Philips SL*18 require all this? ->(you can get them from "Real Goods" if your local stores don't have them) They'll work with a regular X-10 wall switch if they can be used with a light dimmer. Otherwise, no. -- Bill McFadden Tektronix, Inc. P.O. Box 500 MS 58-639 Beaverton, OR 97077 bill@videovax.tv.tek.com, {hplabs,uw-beaver,decvax}!tektronix!videovax!bill Phone: (503) 627-6920 "The biggest difference between developing a missle component and a toy is the 'cost constraint.'" -- John Anderson, Engineer, TI
rsd@sei.cmu.edu (Richard S D'Ippolito) (12/20/90)
In article <10183@pogo.WV.TEK.COM> Bob Tidrick writes: >From my experiance [sic] light bulbs are engineered to have a limited life. Precisely. Have you studied engineering? Rich
spcecdt@deeptht.UUCP (John DuBois) (12/24/90)
In article <1990Dec13.172348.20146@amd.com> phil@brahms.amd.com (Phil Ngai) writes:
+I can not see any reason to use incandescents anymore, unless
+you are getting free power.
+
Or you want to be able to dim the lamp, or a CF won't quite fit,
or you *like* the color of incandescents (yes, you could make a fluorescent
with this color, but I haven't seen them), or you just don't like fluorescent
lamps (I do, but I know people who claim that the best fluorescents, with no
percievable flicker, give them headaches... maybe psycosomatic, but
they just won't use them...), or CFs just wouldn't be appropriate
(chandeliers), or won't work (mini-base lamp fixtures, which I'm not going
to replace; I'm a renter not owner!)...
I looked around this place; what with all the dimmers (5), mini-base
fixtures (13), and other oddities, there isn't much room for improvement.
John DuBois
spcecdt@deeptht.santa-cruz.ca.usmcovingt@athena.cs.uga.edu (Michael A. Covington) (12/25/90)
Another disadvantage of fluorescents is that, with their somewhat lumpy spectrum, they exaggerate the effect of chromatic aberration in an optical system (such as my thick eyeglasses). This happens even if the color looks right. Computer screens have the same problem.
phil@brahms.amd.com (Phil Ngai) (12/27/90)
In article <117@deeptht.UUCP> spcecdt@deeptht.UUCP (John DuBois) writes: | Or you want to be able to dim the lamp, or a CF won't quite fit, I don't know about dimming, I guess you're right, if it matters to you, it doesn't to me. As for fit, I am willing to change the fixture to save energy and help the environment. |or you *like* the color of incandescents (yes, you could make a fluorescent |with this color, but I haven't seen them), or you just don't like fluorescent You could and they do. You ought to look. My current favorite is the "Qlite" by Lights of America. |lamps (I do, but I know people who claim that the best fluorescents, with no |percievable flicker, give them headaches... maybe psycosomatic, but But have these people seen the high frequency CFs? I can wave my hand in front of them and see no flicker. If it were in a fixture such that you couldn't see the shape, I would challenge anyone to be able to tell the difference. |they just won't use them...), or CFs just wouldn't be appropriate |(chandeliers), or won't work (mini-base lamp fixtures, which I'm not going |to replace; I'm a renter not owner!)... Ok, you're right. I guess that's why they pass laws requiring fluorescents in the bath and kitchen of new housing. -- Whatever happened to Global Warming? Could we have some Local Warming?
t31694c@kaira.hut.fi (Tapani Lindgren) (12/28/90)
In article <1990Dec13.172348.20146@amd.com> phil@brahms.amd.com (Phil Ngai) writes: >If you're concerned about bulb life, use a compact fluorescent. Most >of them are rated around 10K hours. If you're concerned about cost, >use a C.F. Over the life of the bulb it will pay itself back many >times. I can not see any reason to use incandescents anymore, unless >you are getting free power. If the light is going to be off most of the time (as many lights in an average household are), a C.F. won't save very much electricity annually. In this case you can get better interest for your money by depositing to a bank than by investing to an expensive C.F. Also, in some areas of the world you have to heat your house anyway for several months of the year (this is the darkest season, too), so the extra heat generated by the conventional light bulbs will not be totally wasted. Tapani Lindgren t31694c@kaira.hut.fi
strong@tc.fluke.COM (Norm Strong) (01/04/91)
In article <1990Dec13.172348.20146@amd.com> phil@brahms.amd.com (Phil Ngai) writes: }In article <4078@osc.COM> jgk@osc.COM (Joe Keane) writes: }|The conclusion is that if you're dropping the supply voltage, or equivalently }|using a higher rated voltage, you're making a mistake. If you're happy with }|the reduced light output, then you should use a lower wattage bulb with the }|right voltage. You'll use less power and also get better color. } }If you're concerned about bulb life, use a compact fluorescent. Most }of them are rated around 10K hours. If you're concerned about cost, }use a C.F. Over the life of the bulb it will pay itself back many }times. I can not see any reason to use incandescents anymore, unless }you are getting free power. I visited a Dennys restaurant yesterday that had been completely retrofitted with fluorescent bulbs. I was VERY favorably impressed with the output and the color temperature. They were Warm White Panasonic units. I'm sold. -- Norm Strong (strong@tc.fluke.com) 2528 31st S. Seattle WA 98144
kludge@grissom.larc.nasa.gov ( Scott Dorsey) (01/04/91)
In article <4078@osc.COM> jgk@osc.COM (Joe Keane) writes: >The conclusion is that if you're dropping the supply voltage, or equivalently >using a higher rated voltage, you're making a mistake. If you're happy with >the reduced light output, then you should use a lower wattage bulb with the >right voltage. You'll use less power and also get better color. Not always. For motion picture use, I'll often use a ballast to run household 150W bulbs at 165V. I get a good 250W of power at almost exactly 3400'K (normal household bulbs are closer to 2800'K at rated voltage). They last about 4 hours on the average, as opposed to the 7 hours that 250W photoflood bulbs last, but they cost about a quarter as much. The color is right on (and is more easily controlled too). -- Scott Dorsey/ Kaptain Kludge NASA Langley Research Center, Aircraft Guidance and Control Branch Disclaimer: Neither NASA nor Lockheed really know anything about what