WE 302 Ringer question

[poplar1]

That may solve the problem of the ringer not being securely attached. However, this is a frequency selective ringer, tuned to only one frequency so that it won't respond to 20~ that is standard.

[Fennec]

That may solve the problem of the ringer not being securely attached. However, this is a frequency selective ringer, tuned to only one frequency so that it won't respond to 20~ that is standard.

Hmm... I do not have a frequency generator, but if it is indeed tuned to a frequency other than the standard 20 Hz, what technique are you supposed to use when restoring SC phones? I just find it a bit strange to think that none of the SC sets would ring on a modern network...

[TelePlay]

Any frequency ringer set for 20 Hz and some set for 30 Hz will ring on a POTS line, 20 Hz at +/- 90 VAC. I have a ring generator that puts out 30 Hz and it works fine for 20 Hz phone but don't know if the reverse is the case, with your phone. Some frequencies get up to ~60 Hz and some down to ~15 IIRC. Yours may be 20 or near there so it may work.

What you can do is attach you ringer to another phone's ringer circuit with clip leads, take one of the phone's ringer leads off it terminal and see if your ringers work with an incoming call.

There are several old topics on how to get a frequency ringer to ring at 20 Hz but it's complicated and involves sawing and filing of the armature area parts. And those ringers being modified were AE type which look much different than yours at the working end.

If your ringer does not work clipped to another phone, easiest is to get a B1A ringer and sell that one frequency ringer on eBay.

[unbeldi]

Any frequency ringer set for 20 Hz and some set for 30 Hz will ring on a POTS line, 20 Hz at +/- 90 VAC. I have a ring generator that puts out 30 Hz and it works fine for 20 Hz phone but don't know if the reverse is the case, with your phone. Some frequencies get up to ~60 Hz and some down to ~15 IIRC. Yours may be 20 or near there so it may work.

I think you mean to say that the 30 Hz generator rings a straight-line ringer.   It should not ring a 20 Hz frequency ringer.

Straight-line ringers have a very broad response range, from ca. 16 Hz to ca. 35 Hz, some perhaps even a little higher.  A 20 Hz frequency ringer, however, only rings for a very narrow range of frequencies centered on 20 Hz.   The FCC specified this range as 19.3 Hz to 20.7 Hz (Type D ringer), and 20±3 Hz for a Type A ringer, which is probably more typical with old instruments.

The FCC specified a straight-line ringer (FCC type B) with the range 15.3 Hz to 68.0 Hz, but AFAIK, this is never achieved with electromechanical bell ringers.

Ref for FCC specs:
Reeve, W.D., Subscriber Loop Signaling and Transmission Handbook—Analog, IEEE New York (1992), p.40

[Alex G. Bell]

Any frequency ringer set for 20 Hz and some set for 30 Hz will ring on a POTS line, 20 Hz at +/- 90 VAC. I have a ring generator that puts out 30 Hz and it works fine for 20 Hz phone but don't know if the reverse is the case, with your phone. Some frequencies get up to ~60 Hz and some down to ~15 IIRC. Yours may be 20 or near there so it may work.

I think this is a misunderstanding.  A "straight line" ringer is intended for 20Hz but is not frequency selective and will work from 16-2/3 to 30Hz and perhaps beyond but a 20Hz frequency ringer will not work at 30Hz or any frequency much different from 20Hz.  It's the percentage frequency difference which counts.  30Hz is 50% off frequency for a 20Hz ringer.  However see comment at end of my reply.

What you can do is attach you ringer to another phone's ringer circuit with clip leads, take one of the phone's ringer leads off it terminal and see if your ringers work with an incoming call.

Frequency ringers require a matching capacitor which resonates the ringer at its intended frequency.  Swapping it into another telephone with a random ringer is likely to result in using the wrong capacitor except perhaps by sheer luck and is likely to result in the ringer not working even if the correct frequency is applied.

There are several old topics on how to get a frequency ringer to ring at 20 Hz but it's complicated and involves sawing and filing of the armature area parts. And those ringers being modified were AE type which look much different than yours at the working end.

If your ringer does not work clipped to another phone, easiest is to get a B1A ringer and sell that one frequency ringer on eBay.

The relatively short clapper on Fennec's phone suggests it's a relatively high frequency ringer, perhaps 40Hz or above and not likely to work at 20 or 30Hz.  A B1A ringer is certainly the best bet and should be easy to find.  A B2A is also acceptable.  A B3A should be avoided since it's low impedance and requires a different ringer capacitor.  I'm assuming the set is a true 302 equipped with a 4-lead 195A capacitor.

[Alex G. Bell]

The FCC specified a straight-line ringer (FCC type B) with the range 15.3 Hz to 68.0 Hz, but AFAIK, this is never achieved with electromechanical bell ringers.

Ref for FCC specs:
Reeve, W.D., Subscriber Loop Signaling and Transmission Handbook—Analog, IEEE New York (1992), p.40

In my early days of phone experimentation, before I had a proper 20Hz ringing source, I used a 6.3VAC 1A filament transformer back-to-back with a 50L6 vacuum tube output transformer.  This delivered about 250VAC @ 60Hz.  B1A ringers and 8-type ringers in 634A subsets worked quite well at this voltage and frequency.  The elevated voltage was required to pass sufficient current through the ringer coil inductance at this 3X higher frequency, out of electrical resonance, and it exceeded the voltage rating of the ringer capacitor, BUT it worked.  I don't recommend it. 

I think the FCC spec is really intended for electronic ringing detection devices such as answering machines.

[TelePlay]

I think you mean to say that the 30 Hz generator rings a straight-line ringer.   It should not ring a 20 Hz frequency ringer.

Yeah, that's what I meant. Thanks.

My Tellabs generator puts out 30 Hz and it rings SL ringers.

I use a D-Sine ring generator for testing ringers. The Tellabs use to go on stage, more and consistent power.

[TelePlay]

Along these lines, ringer frequency, I've always wondered it this would work.

Create a sine wave file increasing from 0 to 100 Hz, play the file on a PC, port the speakers to an amplifier and connect the amp to the ringer and see which frequency would make the ringer work.

Just a thought so it may be a bit more complicated given a ringer is not a speaker. If it did work, it might be an easy way to determine the frequency of a ringer, as if that were really needed anyway (well, for 20 Hz it would be helpful).

Any thoughts?

[poplar1]

Most 1A2 Key System power supplies furnish 30~ for ringing straight line ringers. The older 101Gs provide 20~ but are much larger.

[TelePlay]

Most 1A2 Key System power supplies furnish 30~ for ringing straight line ringers. The older 101Gs provide 20~ but are much larger.

Yes, my Tellabs ringers are rack mountable and designed for 1A2 systems. Nice units hard to find these days.

[unbeldi]

Along these lines, ringer frequency, I've always wondered it this would work.

Create a sine wave file increasing from 0 to 100 Hz, play the file on a PC, port the speakers to an amplifier and connect the amp to the ringer and see which frequency would make the ringer work.

Just a thought so it may be a bit more complicated given a ringer is not a speaker. If it did work, it might be an easy way to determine the frequency of a ringer, as if that were really needed anyway (well, for 20 Hz it would be helpful).

Any thoughts?

With that setup you have the problem that you are trying to drive an 8000 Ω load at 20 Hz with your amplifier.  At 60 Hz, the impedance of the B1A is about 35,000 ohms.  The ringer needs at least about 5 mA of current to operate, so your amplifier has to output a rather high voltage to operate the ringer.

In AGB's experiment he achieved that at 60 Hz with 250 V.        250 V / 35,000 Ω = 7 mA.    Q.E.D.


A better idea is to use those modern and very little Class-D amplifiers.  They are used in laptop computers, portable music players, etc.  and drive a very low impedance output.   If you use an ~ 1:20  ratio transformer backward,   e.g. a 220V transformer that outputs 10 V or so, you have a suitable ringing generator.  However, the input to the Class-D amplifier still needs to have a larger amplitude that your computer audio line output typically provides.

[Alex G. Bell]

Along these lines, ringer frequency, I've always wondered it this would work.

Create a sine wave file increasing from 0 to 100 Hz, play the file on a PC, port the speakers to an amplifier and connect the amp to the ringer and see which frequency would make the ringer work.

Just a thought so it may be a bit more complicated given a ringer is not a speaker. If it did work, it might be an easy way to determine the frequency of a ringer, as if that were really needed anyway (well, for 20 Hz it would be helpful).

Any thoughts?

You would need a circuit which could deliver about 150V.  Although SL ringers are operated nominally from 75-90VAC, frequency ringers require higher operating voltage.  Some S-C or Kellogg catalogs state the nominal voltage required.

An easier way (probably) is to obtain a solid state ringing source, not one using "saturated core" technology such as a Lorain SubCycle, Western Electric Frequency Generator found in typical key system power supplies or Tellabs 8101 for example.  Saturate core devices inherently deliver a fraction of the input line frequency and cannot be adjusted to any other frequency.

Transistor ringing generator circuits consist of an IC or transistor oscillator circuit driving a power amplifier.  The oscillator circuit can be fairly easily modified to use a potentiometer ("volume control" or variable resistor) to control the frequency, resulting in a frequency adjustable ringing source.  Examples are the Tellabs 8102 (transformer output) and Tellabs 8103 (switched-mode, transformerless output).

[Alex G. Bell]

Yes, my Tellabs ringers are rack mountable and designed for 1A2 systems. Nice units hard to find these days.

The WE 118A Frequency Generator is a small compact 30Hz saturated core device used in 551 type "shoebox" Key Service Units.  They seem to show up on eBay from time to time.