tad@beaver.cs.washington.edu> (05/26/90)
In article <8185@accuvax.nwu.edu>, 0004261818@mcimail.com (David Tamkin) writes: > In volume 10, issue 377, Julian Macassey answered some of Steve > Friedl's questions about FCC ringer equivalence numbers. > I have three far simpler ones (I guess): > 1. What does the B or A after an REN mean? A B type ringer must respond to 16 to 68 Hz ringing frequency, and an A ringer only responds to 20 or 30 Hz, +/- 3 Hz. > 2. If the ringer on a telephone can be turned off, does it no longer > count in figuring the total REN load on a line? A phone with the ringer turned off SHOULD have no REN load on the line, but I could imagine an electronic ringer that still has it's detector across the line, but the sound source is off. > 3. Two of my modems *do* have REN's, though neither has any sort of > bell or gong. They check in at "0.4 1.2B" and "0.5A 1.6B" > respectively. My other modem has a speaker and thus does make a noise > (but the speaker is powered by the electric utility, not the telco); > it has an FCC ID but no REN on it at all. What's the question? There are other ringer types (A thru N) for different ringing frequencies. The B type is not frequency selective, but all of the others are. This allows frequency selective ringing on party lines. In article <7911@accuvax.nwu.edu>, tell@oscar.cs.unc.edu (Stephen Tell) writes: > > What is the conversion factor between RENs and somthing your average > > EE can understand, like "milliamps at 90vrms, 20Hz?" A ringing generator that is capable of powering 5 REN should be able to supply ABOUT 5 watts. Tad Cook Seattle, WA Packet: KT7H @ N7HFZ.WA.USA.NA Phone: 206/527-4089 MCI Mail: 3288544 Telex: 6503288544 MCI UW USENET:...uw-beaver!sumax!amc-gw!ssc!tad or, tad@ssc.UUCP
Julian Macassey <julian@bongo.uucp> (05/26/90)
In article <8185@accuvax.nwu.edu>, 0004261818@mcimail.com (David Tamkin) writes: > In volume 10, issue 377, Julian Macassey answered some of Steve > Friedl's questions about FCC ringer equivalence numbers. > I have three far simpler ones (I guess): > 1. What does the B or A after an REN mean? I think I covered this in an earlier posting, but then I could have glossed over it. The letter at the end of the REN numbers covers the "Ringing type" from the notorious Table I. A Ringing type A ringer is sensitive to 20 Hz +-3 and 30 Hz +-3. A B type ringer is sensitive to AC voltage between 15.3 and 68.0 Hz. Just for the curious, a C type ringer is sensitive between 15.3 and 17.4 Hz. There are many classes of ringers. I know that the class is supposed to refer to the frequency coverage, but owing to obscurity in the FCC regs, some labs measure type B ringers (Electronic warble type) as a type A so they can get a lower REN. This does not make it a type A ringer. This makes it a type B ringer measured as a type B. Apart from type B, other ringers cover a narrow frequency range. This frequency selectivity is sometimes used with party lines. It is also one of the factors that limits bell tap in US phones. See an earlier posting of mine where I waffle about this. Yes, most Type B ringers will also respond to frequencies above 68 Hz, like 100 Hz. > 2. If the ringer on a telephone can be turned off, does it no longer > count in figuring the total REN load on a line? I wish this was true. If you look carefully, you will notice that only the output transducer (fancy name for gong, Loudspeaker or piezo disc) is disconnected, but that the power consuming stuff is still on line. In a gong ringer the "off button" is often an arm that obstructs the striker, so no power is saved by turning it off. With electronic ringers, depending on the design, some power may be saved. I have quietly campaigned to have the off switch disconnect the ringer from the line. It does not disconnect the ringer because, it always used to be that way. But that was then when there was maybe only one instrument on the line. These days, you may want the ringer off, because you have too many on line. To take a ringer off line you have to actually disconnect it internally. In the old days, the gong ringer circuit was left in circuit at all times so the telco could sling an AC test circuit down the line at the dead of night and the ringer provided a return path. Note recent postings about strange telephone modems etc going chirp in the night. They also had records of your normal impedance, so any change could tell them if water was seeping into the line etc. It also told them that you had bootlegged a phone on the line. They then got snotty. Most techie types then learned to disconnect the ringer on any bootlegged phones. Now many residential lines have tons of ringers on them and they change continually - must drive the test board guys nuts - any comments from CO types? Most electronic ringers do not provide a good profile to telco test circuits, the exception I know about is the Motorola ringer IC. Motorola does it with a chain of Zeners. So one other point, the "low" or "medium" switch on most electronic ringers is in fact a resistor switched between the ringer IC and the transducer, so the volume is low, but the power consumption is often just as high. My ideal electronic ringer would have the low switch put the resistor on the line before the ringer IC and the off switch would remove the whole circuit from the line. Yes, I know that if the "low" resistor is before the IC, it will make the circuit touchy in the low mode, depending on available power it would either make no difference in volume or silence the bugger entirely. > 3. Two of my modems *do* have REN's, though neither has any sort of > bell or gong. They check in at "0.4 1.2B" and "0.5A 1.6B" > respectively. My other modem has a speaker and thus does make a noise > (but the speaker is powered by the electric utility, not the telco); > it has an FCC ID but no REN on it at all. If the REN is below a 0.1 REN, it can be listed as 0.0 or nothing at all put on the label. See above for dreary details on the funny A and B numbers. In truth, all modems I have seen are type B ringers. To prove this, feed say 60V at 60 Hz (yes power via a regular transformer) to a modem, betya it picks up if in answer mode. I wrote extensively about all this ringer stuff years ago in Popular Communications mag, but I suppose it wasn't all that popular then. Plus of course the editors used to bugger and censor my text so some of the more esoteric stuff was jumbled and meaningless by the time it reached the public and vulgar gaze. Julian Macassey, n6are julian@bongo.info.com ucla-an!denwa!bongo!julian N6ARE@K6IYK (Packet Radio) n6are.ampr.org [44.16.0.81] voice (213) 653-4495
toddi@nsr.bioeng.washington.edu (Todd Inch) (05/29/90)
Note: I attempted to post the below on May 22 but must have fouled up.
Since then, I've read numerous responses. Hopefully, this is a little
less technical. Watts = Volts * Amps, so if Volts is constant, you
can substitute "Amps" in my analogy below, if that is any help.
Somebody mentioned the phone company should be supplying roughly 5
Watts of ring juice, so maybe my analogy was more technically correct
that I had intended. :-)
To clear up possible confusion about the effect of the on/off switch:
On many phones, especially ones with mechanical bells, this will not
effect the REN at all - it still draws just as much current. On some,
it may draw a little less current and have a lower effective REN than
the FCC sticker shows. On very few phones, this may disconnect the
entire ringer circuit from the line and therefore change the REN to
0.0.
On all phones with mechanical bells that I've seen, (insert non-expert
disclaimer here) simply disconnecting the bell inside (with wire
cutters, screwdriver, or a do-it-yourself switch) would have the
effect of drawing no ringing current, thus 0.0 REN.
My favorite method of adding a bell switch to a mechanical bell phone
is to wire the bell to an unused line wire (black or yellow) and then
add one of those cheap hanging-lamp style cord switches to the line
cord. This avoids having to drill holes in the phone, etc. If you
did this to all the phones in your house, you could turn on/off all
the bells at the phone by your bed.
(Write me for details, it's really to boring and elementary for most
readers.)
My original non-posted article:
Stephen J. Friedl, a 3B2-kind-of-guy, asks about REN's and what good
they are.
I'm sure someone will correct me if I'm wrong, but I've always thought
of it as if Ringer Equivalence Numbers were like Watts, that is, the
electrical power required for and drawn by the bell/ringer/chime/etc
during ringing.
For example, if you have a power supply which will safely supply five
watts, you can add any combination of loads which total no more than
five watts.
Each household appliance, for example, is rated X watts on its
nameplate and consumes approximately that much. Add the watts of the
appliances on a circuit to find the total and check if the circuit can
safely supply that much.
It's possible to build an appliance (ringer) to consume fewer watts by
having a more efficient design or by providing less output (noise.)
Most physical bells are designed to use 1.0 REN's because that's the
way they've been for years and it's an acceptable standard which is
fairly cost-effective to achive.
Most "chirpy" ringers use less because they are electronic and
peizo-electric (more efficient and, IMHO, more annoying) rather than
electromechanical like the standard gong-style bells. Or, some of
them on "powered" phones use amplifiers which cause some of the watts
come from the AC power supply instead of the phone line.
The Phone Company's (Central Office) Switch or a PBX, or whatever is
driving the bells, shouldn't "care" how much you're using as long as
you're under the maximum rated "load" - more load will just draw more
current.
Of course, as you approach the maximum load or surpass it, there will
be significant voltage drops and/or current increases (Ohm's law)
which will result in not enough voltage to ring all ringers and/or
activating a "circuit-breaker" or equivalent overcurrent protection
circuit in the switch or pbx.
I've always heard that the "standard" switch or pbx will power about five
REN's worth of ringer-load, but I've had six or seven hooked up before.
I've also noticed the performance of the bells degrade as you add too
many, due to low voltage.
If the REN's are smaller per phone, or on the average, then you can
add more phones. So, you should pay attention if you are approaching
five or more REN's on one line, but this isn't a problem for most
people.
I've never seen a bell with greather than 1.0 REN, except maybe some
oddities I build myself, which the FCC never tested. :-)
A side note: Due to inexpensive construction, most cheap electronic
phones with non-gong ringers (the J-Mart $8 models) will ring at lower
voltages than they really should and often chirp when someone pulse
dials on an extension phone (called bell-tap). They usually also have
less than 1.0 REN's, but these are two effects from one cause (cheap
but efficient all-electronic circuitry) rather than a cause and effect
of each other.
Todd Inch, System Manager, Global Technology,
Mukilteo WA (206) 742-9111 UUCP: {smart-host}!gtisqr!toddi
ARPA: gtisqr!toddi@beaver.cs.washington.eduDavid Tamkin <0004261818@mcimail.com> (05/31/90)
Todd Inch wrote in volume 10, issue 396: :I've always heard that the "standard" switch or pbx will power about five :REN's worth of ringer-load, but I've had six or seven hooked up before. Aha. So that must be the reason I can connect 5.9 REN's of telephones plus .8 REN's of modems and answering machines and still get blasted out of bed if I don't turn the ringers off! Thank you, Mr. Inch. I wish your article had made it through the first time. David Tamkin P. O. Box 7002 Des Plaines IL 60018-7002 +1 708 518 6769 MCI Mail: 426-1818 CIS: 73720,1570 GEnie: D.W.TAMKIN +1 312 693 0591