Old Telephone Ringers (1920s Subsets)

So Bill I really know nothing about old phones, but if you want to find the resonant frequency, just hit the system with a delta function. (ping the gonger?) and the frequency it rings at is the resonant frequency. Now if you can tweak the drive frequency to be close to that 'ping' frequency it may get louder. (you might have to adjust the 'ping' frequency instead.)

George H.

Ah, but it's a nonlinear system -- nothing happens until it hits a bell, which takes some energy out, then it swings over and hits the other, etc. A lot like putting a diode to +V and a diode to -V around a parallel resonant tank -- everything goes fine and dandy until it smacks into a rail.

I might suggest getting a 20Hz generator (motor plus another phone's dynamo??) and tweak it while running.

Tim

Just a thought, but if it does not have a REN, it may not be legal to use on the telephone system.

Bill,

I presume from your IP address that you are in Yankland?

I have a copy of "Herbert & Proctor", 2nd edition, 1941 reprint that covers Britland practice. (H&P was the precursor from which the "Atkinson's Telephony" bible for Brit practice was derived.)

There are descriptions of bells therein, but for adjustments, the book simply refers to screws and springs "that may be used".

In my own garden, I have a number of field telephones all on the same circuit, and the way that I use to set the bells is to get my (ever patient) wife to ring the magneto somewhere else, and then adjust the spacing of the gongs for maximum musicality (cf. Q "What lies in the field and sounds like a cracked bell?" A. "Dung!") and then adjust the screws and tencions for maximum oomph. ("oomph being the SI unit for Smoke" :-) )

I'd suspect that the number of bell sets and subscriber's apparatus are different for you and us, but H&P does describe in detail the innards of various Brit sets.

Interestingly enough, some of my field telephones are Tele "F" from the mid 1930s, and it is interesting to see the various components such as magnetos and wiring looms presented exactly as they appear in the phones.

Generally speaking the old sets are a REN of 1.

I have a WE302 that hooks into my line and rings without issue, same with the Imperial with the 584 subset.

Yes, you see the problem that nothing happens until it hits a bell which knocks everything out of sync with erratic results, but maybe that's the way it was designed?

The ringer is just for display and will not be connected to the phone line. I built a driver circuit using a square wave at about 20Hz to simulate the action. I wired the 2 coils in parallel to reduce the required voltage, and bypassed the capacitor so the mechanism operates fairly well at 20 volts AC. I tried varying the drive voltage and frequency from about 10 volts to 24 volts without much change in action. It seems to work the best at about 20 Hz and 20 VAC.

I could remove the bells and tune the thing for maximum swing of the gonger at lowest voltage, and possibly find a resonant point, but that probably won't help when the bells are replaced and the whole situation changes.

-Bill

On Tue, 15 Sep 2009 18:03:12 -0700 (PDT), Bill Bowden wrote:

:Anybody know the procedure for calibrating old telephone subset :ringers from the 1920s or thereabouts? The ringer is the type used :with old phones where the earpiece was placed against your ear and you :spoke into the mouthpiece on the wall and the ringer box was located :somewhere else. : :The ringer box has the usual 2 bells and wire gonger arrangement that :oscillates between the 2 bells at about 15-25 Hz but somewhat larger :in size than more modern ringers and has 2 magnetic coils instead of :the single coil used in later phones. The ringer box measures 8 X 6 X :3. : :There are a couple screw adjustments on the mechanism, one to control :the oscillating range of the rocker assembly, and another to adjust :the tension of a spring connected to the rocker assembly. The gap :between the 2 bells can also be adjusted by moving the bell positions :closer or farther apart. There is also a permanent magnet in the :magnetic loop around the coils and rocker assembly and I found adding :an additional :magnet improved the operation. : :I understand the mechanics of the ringer should be adjusted for some :resonant frequency (15-25 Hz) but I can't determine what that is, or :how to get there, and the results are somewhat disappointing since the :ringer volume is somewhat less than a more modern phone from the 1960s :or later. I can hear it at 35 feet, but not very loud. : :It seems usable, but not optimum, and I've played around with all the :adjustments. Maybe these old ringers were just not as good as more :modern ones? : :How can I determine the optimum mechanical adjustments? : :-Bill

Adjustment of a magneto ringer depends on the make and manufacturer so it is not possible to give details unless we know what those details are. A photo on alt.binaries.schematics.electronic would be helpful.

In the UK bellsets from arounfd the era in question could look like this

I daresay that US bellsets or magneto ringer mechanisms would be similar.

Adjustment of the former is quite tricky whereas the latter is quite simple and can be done virtually "on the fly" with a source of 17-25Hz ringing being fed into it.

AFAIK it is 20Hz in the US. You should be able to send a sine wave from a function generator into it and then optimize for response. The amplitude won't be very high because most function generator can't deliver more than 10-20Vpp. So for that experimental phase you'll have to move the bells in a bit. This is how I changed the resonant circuit (there's also a capacitor) on our 1927 Western Electric to another ringer frequency when living in Europe.

Oh, they were, just like back in Sheriff Taylor's house. Ours is in the kitchen but when the bedroom door is open and it rings you fall out of the bed :-)

So I made it a base plate and placed a Kellog switch below to turn it off.

Move the phone to the lab bench and try the function generator. You haven't posted the exact type number and make but this page might help:

Well, typical ringing generators are from around16Hz to 56Hz, with an AC voltage of around 90V. There are all the different frequencies to allow for party line use, with each party having a different frequency ringer.

Charlie

But that was a long time ago. Sets used on party lines may still be customized to resonate at a certain frequency but the CO should nowadays be pretty much standardized in ringer frequency. Except maybe for the occasional case way out in the boonies.

But you brought up an idea, maybe Bill's phone was made to resonate higher because it came out of an old house on such a party line. I think he should really find out where his phone resonates and if needed change out a cap. Of course that cap must be of same vintage or at least look antique enough :-)

Really old phone systems used "pattern" ringing, such as short-short-long, controlled via the crank. I can recall my grandmother announcing that's so-and-so's ring, then listening in ;-)

...Jim Thompson

: :Really old phone systems used "pattern" ringing, such as :short-short-long, controlled via the crank. I can recall my :grandmother announcing that's so-and-so's ring, then listening in ;-) : : ...Jim Thompson

This is known simply as a "magneto party line service". In some cases a magneto party line could be single wire earth return up to 60 or more miles long. In some cases the top wire of a long fence-line would be used (part private erected line) but if it rained (not often out beyond the black stump) the wet wooden posts would result in high leakage causing hum, and ringing got shunted quite badly.

Yep. Where my Grandparents Thompson lived, the "community" owned the phone system.

...Jim Thompson

IIRC, some of those adjustments were to control the ringing frequency. Giving a greater spread gave a lower frequency, etc...

Charlie

I think that is also the case on our Western Electric but I wasn't quite able to pull it to the European ringer frequency without a capacitor change.

around

No wonder it does not work right, you mucked the circuit. Use a 20 Hz sine wave anyway, that IS part of how it works.

:On Sep 15, 7:49 pm, Tim Williams wrote: :> On Sep 15, 8:35 pm, George Herold wrote: :>

:> > So Bill I really know nothing about old phones, but if you want to :> > find the resonant frequency, just hit the system with a delta :> > function. (ping the gonger?) and the frequency it rings at is the :> > resonant frequency. :>

:> Ah, but it's a nonlinear system -- nothing happens until it hits a :> bell, which takes some energy out, then it swings over and hits the :> other, etc.  A lot like putting a diode to +V and a diode to -V around :> a parallel resonant tank -- everything goes fine and dandy until it :> smacks into a rail. :>

:> I might suggest getting a 20Hz generator (motor plus another phone's :> dynamo??) and tweak it while running. :>

:> Tim : :Yes, you see the problem that nothing happens until it hits a bell :which knocks everything out of sync with erratic results, but maybe :that's the way it was designed? : :The ringer is just for display and will not be connected to the phone :line. I built a :driver circuit using a square wave at about 20Hz to simulate the :action. I wired the 2 coils in parallel to reduce the required :voltage, and bypassed the capacitor so the mechanism operates fairly :well at 20 volts AC. I tried varying the drive voltage and frequency :from about 10 volts to 24 volts without much change in action. It :seems to work the best at about 20 Hz and 20 VAC. : :I could remove the bells and tune the thing for maximum swing of the :gonger at lowest voltage, and possibly find a resonant point, but that :probably won't help when the bells are replaced and the whole :situation changes. : :-Bill

As KosephKK has said "you mucked the circuit".

the ringer is a magnetically polarised device and the windings are designed for series operation such that the polarity of each coil on successive half cycles aids one pole while repelling the other. You can't connect the windings in parallel and expect it to work. Also the voltage must be at least 40Vac for effective operation. Real worl exchange ringing machines for ringing bells like this were nominally 90Vac rms and the waveform was quite peaky.

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I don't see why it should matter if the windings are in series or parallel, since the magnetic phasing can be changed by reversing the connections to either winding. So, there are 2 possible ways to connect the windings in parallel, and only one arrangement works.

Yes, I imagine the voltage was fairly high using a cap in series.The cap measures 1uF which has a reactance of about 8000 ohms at 20 Hz. which drops most of the voltage. But the cap isn't needed since it won't be connected to the phone line. The ringer operates somewhat from a 5 volt peak sinewave from a function generator connected directly to the parallel windings. But I still can't find a mechanical resonant point.

-Bill

:On Sep 21, 6:02 pm, Ross Herbert wrote: :> On Wed, 16 Sep 2009 17:31:23 -0700 (PDT), Bill Bowden :> wrote: :>

:> :On Sep 15, 7:49 pm, Tim Williams wrote: :> :> On Sep 15, 8:35 pm, George Herold wrote: :> :>

:> :> > So Bill I really know nothing about old phones, but if you want to :> :> > find the resonant frequency, just hit the system with a delta :> :> > function. (ping the gonger?) and the frequency it rings at is the :> :> > resonant frequency. :> :>

:> :> Ah, but it's a nonlinear system -- nothing happens until it hits a :> :> bell, which takes some energy out, then it swings over and hits the :> :> other, etc.  A lot like putting a diode to +V and a diode to -V around :> :> a parallel resonant tank -- everything goes fine and dandy until it :> :> smacks into a rail. :> :>

:> :> I might suggest getting a 20Hz generator (motor plus another phone's :> :> dynamo??) and tweak it while running. :> :>

:> :> Tim :> : :> :Yes, you see the problem that nothing happens until it hits a bell :> :which knocks everything out of sync with erratic results, but maybe :> :that's the way it was designed? :> : :> :The ringer is just for display and will not be connected to the phone :> :line. I built a :> :driver circuit using a square wave at about 20Hz to simulate the :> :action. I wired the 2 coils in parallel to reduce the required :> :voltage, and bypassed the capacitor so the mechanism operates fairly :> :well at 20 volts AC. I tried varying the drive voltage and frequency :> :from about 10 volts to 24 volts without much change in action. It :> :seems to work the best at about 20 Hz and 20 VAC. :> : :> :I could remove the bells and tune the thing for maximum swing of the :> :gonger at lowest voltage, and possibly find a resonant point, but that :> :probably won't help when the bells are replaced and the whole :> :situation changes. :> : :> :-Bill :>

:> As KosephKK has said "you mucked the circuit". :>

:> the ringer is a magnetically polarised device and the windings are designed for :> series operation such that the polarity of each coil on successive half cycles :> aids one pole while repelling the other. You can't connect the windings in :> parallel and expect it to work. Also the voltage must be at least 40Vac for :> effective operation. Real worl exchange ringing machines for ringing bells like :> this were nominally 90Vac rms and the waveform was quite peaky. : :I don't see why it should matter if the windings are in series or :parallel, since the magnetic phasing can be changed by reversing the :connections to either winding. So, there are 2 possible ways to :connect the windings in parallel, and only one arrangement works. : :Yes, I imagine the voltage was fairly high using a cap in series.The :cap measures 1uF which has a reactance of about 8000 ohms at 20 Hz. :which drops most of the voltage. But the cap isn't needed since it :won't be connected to the phone line. The ringer operates somewhat :from a 5 volt peak sinewave from a function generator connected :directly to the parallel windings. But I still can't find a mechanical :resonant point. : :-Bill

Upon reflecting, you are correct that a parallel connection with correct phasing will do the same thing. However, the sensitivity of the bell will be markedly reduced since the current requirement to produce the same magnetic effect will increase.

I don't know why you are having such a problem in getting the bell to operate correctly. If you feed it the right frequency and voltage it is very simple to adjust for maximum effectiveness. A 5V sinewave is just too low in amplitude and anyway, such bells respond better if the ac waveform has a rather peaked waveform. When I was a trainee tech learning about magneto phones the instructor always reminded us that the shape of the armature of the hand turned magneto was specifically designed to produce a "spiked" waveform because the bells would then receive an initial "kick" to overcome the magnetic bias and the gongs would be struck slightly harder than if a pure sinewave were used.

Here are a couple of links on magneto bells which might help.