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Odd question regarding an old rotary telephone

Wed Aug 23, 2017 4:16 pm

Hey all. I have an old rotary telephone that I've been taking apart to repurpose for other projects but I was looking at the ringer on the phone and was wondering if I could hook it up to battery supply with an on off switch and a temporary on button to make it ring.

Is that possible? Any ideas on the amount of batteries needed? I always thought the old phones ran on a low voltage power supply but I really don't know shit or if this will work.

Re: Odd question regarding an old rotary telephone

Wed Aug 23, 2017 4:45 pm

Ringers want 70-90 volts AC.

Re: Odd question regarding an old rotary telephone

Thu Aug 24, 2017 12:18 pm

crochambeau wrote:Ringers want 70-90 volts AC.



sweet jesus. so if I take apart this old ass phone and want to wire up the ringer to a battery and an on/off switch it would require 70-90 volts?
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Re: Odd question regarding an old rotary telephone

Thu Aug 24, 2017 1:07 pm

It was designed for 70-90 volts AC. Lower voltages may move the clapper..

If you're using a battery the clapper will only move toward one of the bells, you need AC to swing it back and forth.

Re: Odd question regarding an old rotary telephone

Thu Aug 24, 2017 1:37 pm

crochambeau wrote:It was designed for 70-90 volts AC. Lower voltages may move the clapper..

If you're using a battery the clapper will only move toward one of the bells, you need AC to swing it back and forth.



Damn, I always thought that this was a low voltage device that ran off of those 4 tiny wires. That's a bummer.

Re: Odd question regarding an old rotary telephone

Thu Aug 24, 2017 1:44 pm

DC supply of -48 if memory serves, then the ringer is AC on top of that.

Not terribly low voltage, remember, back on the day this stuff traveled miles of wire.

Re: Odd question regarding an old rotary telephone

Thu Aug 24, 2017 3:13 pm

you can do it with a battery or low voltage dc supply if it can push enough current. i did this for someone with an arduino and a transformer. the frequency needs to be ~18 HZ iirc, that is what they were designed for. I think in the end i had it working with only ~ 40VAC but ymmv.

Basically use the dc to power an oscilator (AC signal) then drive the AC through a step up transformer. Attach the other side of the transformer to the clapper.
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Re: Odd question regarding an old rotary telephone

Thu Aug 24, 2017 3:25 pm

Just pull a Schumann and run the whole device off an AC power supply, with an overcomplicated rectification circuit and a bunch of extra parts. That's metal. :rock:
-Brett

Re: Odd question regarding an old rotary telephone

Fri Aug 25, 2017 11:58 am

thanks for the info (most of which I didn't understand. I think I'm going to get a battery power alarm clock and take it apart and wire up the ringer. :)

Re: Odd question regarding an old rotary telephone

Mon Aug 28, 2017 11:25 pm

you could also just find/get an Coil style doorbell, same idea as a tattoo machine, they run on DC less than 12V


http://www.mansionschools.com/electric- ... gK2m_D_BwE
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