jfsenior@vax1.tcd.ie (K.) (01/30/90)
OK,
Sorry to post this here, but rec.arc.generators doesn't seem to exist.
Can anyone give me DETAILS of how to build an arc generator, such as is seen
in science fiction film of the 30/40's etc.
I call it an arc generator, but I expect that is incorrect....
A reference to a book or magazine article on the subject would also be helpful.
This is the sort of thing I mean:-
o ^ o
\ ^ ^ /
\^ /
\ /
\/
------
Anyone have any idea what I'm talking about?
Thanking y'all in advance.
+--------------------------------------+---------------------------------+
|Sorry, Witty disclaimer not included. | JFSENIOR@vax1.tcd.ie |
|"Quia labor vincit Omnia," sez who? | Or something similar. |
+--------------------------------------+---------------------------------+dnl@goanna.oz.au (David "IGOR" Latter) (01/30/90)
In article <5237@vax1.tcd.ie>, jfsenior@vax1.tcd.ie (K.) writes: > OK, > > Sorry to post this here, but rec.arc.generators doesn't seem to exist. > > Can anyone give me DETAILS of how to build an arc generator, such as is seen > in science fiction film of the 30/40's etc. > > I call it an arc generator, but I expect that is incorrect.... > > A reference to a book or magazine article on the subject would also be helpful. > > This is the sort of thing I mean:- > o ^ o > \ ^ ^ / > \^ / > \ / > \/ > ------ > Anyone have any idea what I'm talking about? > ------------------ What you want to know about is called a "Tesla Coil" It is a simple high voltage, high frequency (well....low rf anyway) arc generator, sort of a fore-runner to the early arc transmitters. A simple unit I built a few years ago generated approx 180 KV and was 30x30x45 cm and operated off 6V dc using an induction coil. I would suggest you find a book on Nikola Tesla. The other device is known as "jacobs ladder" which when used with a high voltage source such as a tesla coil, is rather fun to play with... It is just two thick upright wires shaped as: \ / \ / The arc starts at the inside curve of the \ / ladder and rises to the top to eventually / \ "blow-out" when the arc distance cannot be ==|==|= mounting base maintained. There are a few other tricks that you can do with a good low power coil... like holding a flouro light near it, or plasma displays (try an old globe)etc. Hope this is of interest.
greene@venice.SEDD.TRW.COM (John Greene) (01/31/90)
In article <5237@vax1.tcd.ie> jfsenior@vax1.tcd.ie (K.) writes: > >Can anyone give me DETAILS of how to build an arc generator, such as is seen >in science fiction film of the 30/40's etc. > >I call it an arc generator, but I expect that is incorrect.... > ------ It's called 'Jacob's Ladder' and is quite easy to build. Take two pieces of heavy gage wire (clothes hanger) or even copper piping and one neon transformer. I have a 12kv, 30ma transformer which does the job nicely. Attach each wire to each of the tranformers outputs and bend them such that they are close enough on the bottom for and arc to jump across and then gradually separate them as they go up, with the power off of course. The heat from the arc carries it up to the top where it breaks and a new one starts at the bottom. Good for about 3 minutes of entertainment. ....now where did I put that tesla coil....... -- John E. Greene "People are just like frankfurters....You have to decide if you're going to be a hot dog or just another wiener" DLR TRW Systems Engineering and Development Division ARPA: greene@venice.sedd.TRW.COM USENET: ..trwrb!venice!greene
dkazdan@cwsys2.cwru.edu (David Kazdan) (01/31/90)
>>Can anyone give me DETAILS of how to build an arc generator, such as is seen >>in science fiction film of the 30/40's etc. >> >> ------ >It's called 'Jacob's Ladder' and is quite easy to build. Take two pieces >of heavy gage wire (clothes hanger) or even copper piping and one neon >transformer. I have a 12kv, 30ma transformer which does the job nicely. CAUTION: LETHAL DEVICE. I'm sure you all knew that--but it's worth repeating (we need to keep the NetNews bandwidth up, you know) --David
scott@hpcvca.CV.HP.COM (Scott Linn) (02/01/90)
/ hpcvca:sci.electronics / jfsenior@vax1.tcd.ie (K.) / 9:18 am Jan 29, 1990 / >Can anyone give me DETAILS of how to build an arc generator, such as is seen >in science fiction film of the 30/40's etc. > > This is the sort of thing I mean:- > o ^ o > \ ^ ^ / > \^ / > \ / > \/ > ------ Well I can't give you exact DETAILS, but I can shed some light. It is usually called a Jacobs' Ladder. It can be easily built using a transformer used for driving neon tube displays. Simply attach some rods at the appropriate spacing and angle to the transformer, and you have it. Spacing is empirical; don't zap yourself! Scott Linn scott@hpcvcbh HP - Northwest IC Division
maj@hpfinote.HP.COM (Mike Jassowski) (02/01/90)
This is the sort of thing I mean:-
o ^ o
\ ^ ^ /
\^ /
\ /
\/
------
Anyone have any idea what I'm talking about?
----------
Sounds like you're talking about a "Jacob's Ladder". Really pretty easy
to build if you can get your hands on a neon sign transformer (available
at most good surplus stores). These transformers generally put out 5-15kv
at a few mA.
Connect a couple of coat hangers to the outputs, bent sort of like:
\ /
\ /
\ /
\ /
\ /
\ /
\ /
\ /
____| |____
| |
to neon sign xfmr
The gap at the bottom of the 'V' shape should be pretty close (I think
that air gaps will conduct at ~10kv/cm--it should be less than this).
The long part of the 'V' should be as straight as possible.
The way this works is: the sign transformer has enough juice to
ionize the air at the closest part of the gap. The ionized air heats up
and rises. The ionized air is a low resistance path, and will continue
to conduct as the leads separate.
Air currents near the device can disturb the ionized air and cause the arc
break prematurely.
Standard Disclaimer: High Voltage can kill. Please be careful.
--Mike Jassowskitomb@hplsla.HP.COM (Tom Bruhns) (02/01/90)
dnl@goanna.oz.au (David "IGOR" Latter) writes: >In article <5237@vax1.tcd.ie>, jfsenior@vax1.tcd.ie (K.) writes: >> OK, >> >> Can anyone give me DETAILS of how to build an arc generator, such as is seen >> in science fiction film of the 30/40's etc. >> >> ... >> >> Anyone have any idea what I'm talking about? >> >------------------ >What you want to know about is called a "Tesla Coil" For many simple experiments, a neon tube transformer can also be used. These produce a limited current at rather high voltage (about 20 kV; generally about 20 mA). They are short-circuit protected, but be aware that they can be LETHAL. The output is simply a voltage-stepped- up version of the input, so the frequency is still 60 Hz (though probably with quite a bit of harmonic distortion). Since they don't produce RF, there are a lot of experiments that you can't use them for that the tesla coil might be good for. (If you change the frequency used to excite a neon light bulb, for example, the color goes from the usual orange to a pretty purple as you get up into the 10's of MHz...) > >Hope this is of interest. >----------
dnewton@carroll1.cc.edu (Dave Newton the Late) (02/01/90)
In article <1990Jan31.155511.20128@usenet.ins.cwru.edu> dkazdan@cwsys2.UUCP (David Kazdan, M.D.) writes: >>transformer. I have a 12kv, 30ma transformer which does the job nicely. >CAUTION: LETHAL DEVICE. Not necessarily--I've been zapped by tesla's and other low-current/high- voltage&frequency devices before. One threw me across a basement (Dave, why are you on the laundry table?) but I'm still alive. Decidedly uncomfortable. -- David L. Newton | uunet!marque!carroll1!dnewton (414) 524-7343 (work) | dnewton@carroll1.cc.edu (414) 524-6809 (home) | 100 NE Ave, Waukesha WI 53186
darus@chinet.chi.il.us (james wygralak) (02/01/90)
In article <5237@vax1.tcd.ie> jfsenior@vax1.tcd.ie (K.) writes: >OK, > >Sorry to post this here, but rec.arc.generators doesn't seem to exist. > >Can anyone give me DETAILS of how to build an arc generator, such as is seen >in science fiction film of the 30/40's etc. > >I call it an arc generator, but I expect that is incorrect.... > >A reference to a book or magazine article on the subject would also be helpful. > > This is the sort of thing I mean:- > o ^ o > \ ^ ^ / > \^ / > \ / > \/ > ------ >Anyone have any idea what I'm talking about? > >Thanking y'all in advance. > Yes. What you are refering to is known as a jacobs ladder. They are quite simple to build. They are also DANGEROUS because they envolve very high voltage. The first one I built used a neon sign transformer for the power supply. The output was about 14,000 volts. Input was 120. All you need is two metal rods in the shape of a V. It is best to have them adjustable so you can vary the gap and angle. Connect one output terminal from the transformer to each rod. Start with about a 1/4" gap on the bottom and a fairly shallow angle (close to parallel) Turn it on and see what happens. If it doesnt work, you just have to keep adjusting it till it works. WARNING: THE VOLTAGES INVOLVED ARE DEADLY! DO NOT TRY TO ADJUST THE RODS WHILE THE POWER IS ON! YOU WILL GET VERY DEAD! Also, do not operate near any flamable materials. The arc can start a fire if it comes in contact with anything flamable. ------------------------------------------------------------------------------ I make no warantees. Express or Implied. Use this information at your own risk! Darus@chinet.chi.il.us KA9LTY Unemployed BSEET looking for a gig. -------------------------------------------------------------------------------
rspangle@jarthur.Claremont.EDU (Randy Spangler) (02/01/90)
I understand how transformers work fine (I've had E&M). But how do you get the high frequency with that much voltage? I've seen pictures in Edmund Scientific and such, and it doesn't look like too much circuitry is involved. Also, how high is high frequency for an average Tesla coil? I too would love to build one; I don't want to shell out the $150 or whatever Edmund wants for one. -- -------------------------------------------------------------------------- | Randy Spangler | The less things change, the | | rspangle@jarthur.claremont.edu | more they remain the same | --------------------------------------------------------------------------
dkazdan@cwsys2.cwru.edu (David Kazdan) (02/01/90)
In article <1141@carroll1.cc.edu> dnewton@carroll1.cc.edu (Dave Newton the Late) writes: >In article <1990Jan31.155511.20128@usenet.ins.cwru.edu> dkazdan@cwsys2.UUCP (David Kazdan, M.D.) writes: >>>transformer. I have a 12kv, 30ma transformer which does the job nicely. >>CAUTION: LETHAL DEVICE. > > Not necessarily--I've been zapped by tesla's and other low-current/high- >voltage&frequency devices before. One threw me across a basement (Dave, why >are you on the laundry table?) but I'm still alive. Decidedly uncomfortable. > I don't mean to be a killjoy, but neon sign transformers are ***not*** low-current devices (Tesla coils are). They will source 30 mA without any problem and will do so at over ten kilovolts. That is cardiac standstill and a nasty frying fat smell when the body is found. BTW, I have a surplus neon sign transformer and have been meaning to get around to building a Jacob's ladder with it. What's a good insulator to use for the base? 73, --David
logajan@ns.network.com (John Logajan) (02/02/90)
rspangle@jarthur.Claremont.EDU (Randy Spangler) writes: >But how do you get the high frequency with that much voltage? The high frequency is usually generated on the primary side of the xformer. Tesla used spark-gap driven oscillators (I believe). Normally the turns-ratio of the xformer, primary to secondary, determines the step-up (or step-down) ratio, but this is not true in circuits that are in resonance. (Or so the book on Tesla claims.) Apparently you can get "extra" step-up in a resonant xformer. Tesla's spark-gap apparatus was self-resonant and so tuning wasn't as critical as if you had an oscillator driven by a fixed reference freq. Then you would need to tune the osc or the coil to each other. -- - John Logajan @ Network Systems; 7600 Boone Ave; Brooklyn Park, MN 55428 - logajan@ns.network.com, john@logajan.mn.org, 612-424-4888, Fax 424-2853
greene@venice.SEDD.TRW.COM (John Greene) (02/02/90)
In article <4079@jarthur.Claremont.EDU> rspangle@jarthur.Claremont.EDU (Randy Spangler) writes: >I understand how transformers work fine (I've had E&M). > >But how do you get the high frequency with that much voltage? >I've seen pictures in Edmund Scientific and such, and it doesn't look >like too much circuitry is involved. The primary of a transformer is used as part of a tank circuit that is 'rung' with an impulse generated by a spark gap. You need some sort of high voltage source from either a neon sign transformer or a voltage multiplier circuit that provides high voltage DC. It looks something like this: HV source---------| |--------|------) (-------O output electrode spark | ) ( gap CAP --- ) ( --- ) ( |______) ( | ( GND ( ( (-------| | GND When the spark jumps the gap it rings the tank circuit at it's resonant frequency. Usually several hundred Kilohertz to a couple of Megahertz. The capacitors are made several different ways but the most common seems to be to use a double sided PC board and etch away the copper from the edges a quarter of an inch or so. The size of the board will determine the capacitance. The secondary has as many turns on it as you have wire. -- John E. Greene "People are just like frankfurters....You have to decide if you're going to be a hot dog or just another wiener" DLR TRW Systems Engineering and Development Division ARPA: greene@venice.sedd.TRW.COM USENET: ..trwrb!venice!greene
markz@ssc.UUCP (Mark Zenier) (02/02/90)
In article <4079@jarthur.Claremont.EDU>, rspangle@jarthur.Claremont.EDU (Randy Spangler) writes: > > But how do you get the high frequency with that much voltage? There are a lot of turns in the secondary. Think of a tesla coil as a relaxation oscillator using a spark gap. When the gap arcs, this drives the primary coil with a abrupt pulse. This couples into the secondary, which is resonant in the medium wave frequencies. > Also, how high is high frequency for an average Tesla coil? 100 Khz to 1 Mhz, the bigger the coil the lower the frequency. In this range, you have the option of interfering with aeronautical beacons, a maritime distress frequency, and all of your neighbors AM radios. markz@ssc.uucp
frankb@hpsad.HP.COM (Frank Ball) (02/02/90)
*I don't mean to be a killjoy, but neon sign transformers are ***not*** *low-current devices (Tesla coils are). They will source 30 mA without any *problem and will do so at over ten kilovolts. That is cardiac standstill *and a nasty frying fat smell when the body is found. *BTW, I have a surplus neon sign transformer and have been meaning to get *around to building a Jacob's ladder with it. What's a good insulator *to use for the base? I got a NEW Jefferson 15 KV 60 mA transformer for $58 from a surplus store. A friend in the sign business said thats half of wholesale, so I figure it was a good deal. Yes this can definiatly be dangerous. Use the one hand rule (keep one hand in your pocket or behind your back when the power is on) so if you do get a shock, it hopefully will not be applyed across your heart. I just use the transformer as a base. I use some steel wire, about 14 gauge for the electrodes. Connect the wire to the transformer terminals and bend as necessary. Frank Ball frankb@hpsad.HP.COM
greg@sj.ate.slb.com (Greg Wageman) (02/03/90)
Opinions expressed are the responsibility of the author. In article <1990Jan31.155511.20128@usenet.ins.cwru.edu> dkazdan@cwsys2.UUCP (David Kazdan, M.D.) writes: >>>Can anyone give me DETAILS of how to build an arc generator, such as is seen >>>in science fiction film of the 30/40's etc. >>> >>> ------ >>It's called 'Jacob's Ladder' and is quite easy to build. Take two pieces >>of heavy gage wire (clothes hanger) or even copper piping and one neon >>transformer. I have a 12kv, 30ma transformer which does the job nicely. > >CAUTION: LETHAL DEVICE. > >I'm sure you all knew that--but it's worth repeating (we need to keep >the NetNews bandwidth up, you know) Another warning-- devices which produce sparks like this generate lots and lots of ozone, which (at this level of the atmosphere) is a pollutant, not a benefit. It's not good for you. Don't use this device in an enclosed room for long periods. (It'll also wreak havoc with radio and TV reception.) Have fun anyway. Copyright 1990 Greg Wageman DOMAIN: greg@sj.ate.slb.com Schlumberger Technologies UUCP: {uunet,decwrl,amdahl}!sjsca4!greg San Jose, CA 95110-1397 BIX: gwage CIS: 74016,352 GEnie: G.WAGEMAN Permission is granted for reproduction provided this notice is maintained.
knudsen@cbnewsd.ATT.COM (michael.j.knudsen) (02/03/90)
To build a Jacob's Ladder, you don't need to build anything
as complex as a Tesla coil. For a JL, just get an old ignition
transformer from a junked oil furnace. Biggest problem is
getting the two wire electrodes shaped just right.
Safety is a big concern here. Teslas put out RF at low microamperage
and can maybe burn you but not shock you.
Furnace igniters are just the reverse -- good old 60 cycles
at quite a few milliamps. So do be careful.
Also put some kind of plexiglas or glass chimney or box around
the beast while it's on public display, so nobody can touch
it while operating.
Although it is fun to blow out the spark halfway up and
watch it restart from the bottom, or to hold a slip
of paper halfway up and watch holes burn thru it, etc.
Neon sign transformers are even better, if you can scrounge one.
More voltage, less current.
--
Mike Knudsen knudsen@ihlpl.att.com (708)-713-5134
"Round and round the while() loop goes;
Whether it stops," Turing says, "no one knows."jharkins@sagpd1.UUCP (Jim Harkins) (02/03/90)
In article <1141@carroll1.cc.edu> dnewton@carroll1.cc.edu (Dave Newton the Late) writes: >In article <1990Jan31.155511.20128@usenet.ins.cwru.edu> dkazdan@cwsys2.UUCP (David Kazdan, M.D.) writes: >>>transformer. I have a 12kv, 30ma transformer which does the job nicely. >>CAUTION: LETHAL DEVICE. > > Not necessarily--I've been zapped by tesla's and other low-current/high- >voltage&frequency devices before. One threw me across a basement (Dave, why >are you on the laundry table?) but I'm still alive. Decidedly uncomfortable. Depends on where you touch it. I built a tesla coil from a Popular Electronics (june 1966 rings a bell...) so I know a bit about them. If you touch the 120V input, or the xxKV output of the neon tube xformer then can I have your stereo? If you touch the tip of the coil itself then expect a nasty burn as this is 100+ KV (thats over 100,000 volts, son) at a high frequency. High frequencies tend to travel along the skin instead of penetrating, this has probably saved a few teenagers lives. Me? I was always careful as hell and never once got zapped by anything. jim
darus@chinet.chi.il.us (james wygralak) (02/03/90)
In article <1141@carroll1.cc.edu> dnewton@carroll1.cc.edu (Dave Newton the Late) writes: >In article <1990Jan31.155511.20128@usenet.ins.cwru.edu> dkazdan@cwsys2.UUCP (David Kazdan, M.D.) writes: >>>transformer. I have a 12kv, 30ma transformer which does the job nicely. >>CAUTION: LETHAL DEVICE. > > Not necessarily--I've been zapped by tesla's and other low-current/high- >voltage&frequency devices before. One threw me across a basement (Dave, why >are you on the laundry table?) but I'm still alive. Decidedly uncomfortable. > The key word here is high frequency. There is a phenomenon know as the skin-effect. It refers to the tendency of high frequency signals to travel along the surface of a conductor. This will cause HF current to pass along the surface of your skin and not through the body. A properly tuned tesla coil is a high frequency generator. A jacobs ladder is NOT a high frequency device. It operates at 60hz. Another point: It takes very little current to kill a person. As little as 0.1 milli-amps of current passing through the body is lethal. 12kv is plenty to develop this much current if you were to grab the posts of a jacobs ladder while it is energized. ------------------------------------------------------------------------------ darus@chinet.chi.il.us KA9LTY BSEET looking for a real job. ------------------------------------------------------------------------------
Nagle@cup.portal.com (John - Nagle) (02/05/90)
A Jacobs' Ladder will work better if enclosed in a tall plexiglas
or glass tube. This keeps the plasma from dispersing as it rises, and the
arc will be more stable.
Note that arcs generate ozone, which is a corrosive gas. Adequate
ventilation is required.
John Naglesheriffp@spock (Peter Sheriff) (02/06/90)
I believe that these things are called a 'Jacob's Ladder'. I have
seen ads in such mags as Popular Science and Popular Mechanics for the
coils that you need to build the thing. I also believe that they generate
much RF interference so you may get complaints from the neighbors.
Petewiml@blake.acs.washington.edu (William Lewis) (02/13/90)
In article <1990Feb3.030018.25484@chinet.chi.il.us> darus@chinet.chi.il.us (james wygralak) writes: >In article <1141@carroll1.cc.edu> dnewton@carroll1.cc.edu (Dave Newton the Late) writes: >>In article <1990Jan31.155511.20128@usenet.ins.cwru.edu> dkazdan@cwsys2.UUCP (David Kazdan, M.D.) writes: >>>CAUTION: LETHAL DEVICE. >> >> Not necessarily--I've been zapped by tesla's and other low-current/high- > >The key word here is high frequency. There is a phenomenon know as the >skin-effect. It refers to the tendency of high frequency signals to travel ... >A jacobs ladder is NOT a high frequency device. It operates at 60hz. A Jacob's Ladder can presumably operate at any frequency, down to DC. I'd assume that they would operate better at DC than high frequencies, for the same reason relays can handle higher AC currents than DC, but all you need is a lot of potential drop and a gas between the electrodes. >12kv is plenty to develop this much current if you were to grab the >posts of a jacobs ladder while it is energized. ^^^^^^^^ ^^^^^^^^^^^^^^^^^^^^^^^^ Ye gods, anyone THAT stupid probably deserves it ... =8( -- wiml@blake.acs.washington.edu (206)526-5885 Seattle, Washington