[SML] Telephone line simulator

[Jerry Durand]

For the low of budget people, if you just need to generate ring you can do so with bits you might have laying around.

You'll need:
An audio source for 20Hz sine wave, pulsed in whatever cadence you want.

An audio amplifier, I used a Radio Shack PA amplifier for one setup.  Doesn't need to be quality, just function.

If the amplifier has 70 volt line out, you can skip the transformer in the next line.

An 8 ohm to 70 volt PA transformer.

A blocking capacitor, steal a RUN capacitor from an induction motor you're not using.

The capacitor isn't strictly needed, but does limit current.

Circuit is audio source > amplifier > 8-transformer-70 > capacitor in series with one lead > telephone.

Be sure and cut the audio when the actor picks up, you don't want to blast his ear with the ring signal.  Maybe remove the speaker from the phone.

Experiment to find what works well with your phone and gear.



⁣---
Jerry Durand, Durand Interstellar, Inc. +1 408 356-3886
www.DurandInterstellar.com & www.DurandInterstellar.ru​

On Apr 10, 2020, 22:33, at 22:33, Dave Vick via Stagecraft <stagecraft at theatrical.net> wrote:
>On Fri, Apr 10, 2020 at 4:16 PM Nigel Worsley via Stagecraft
><stagecraft at theatrical.net> wrote:
>
>> Already on the list is the ability to provide the right tones and
>> ringing frequencies for worldwide use and a USB port so it can be
>> triggered by show control software etc.
>
>
>Y'might consider making that a MIDI input rather than USB...
>Or MIDI throughput?
>
>-- 
>Dave Vick
>517-749-3859
>Yeah; *that* guy...
>
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