Telephone ringer circuit ?

Hi! What is the best way to make 24 telephones ring ? I have gathered quite a bit of information at

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about this. See that page to know more.

My favorite way to it is with an audio signal, I think. If I do it this way, which cheap amplifier can give me 90VAC ?

Thanks a lot !

aalex (crossposting to sci.electronic.circuit and sci.electronics.misc)

Reply to
aalex
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Hey! You 'think' that you invented this problem. Try to investigate what has/is done in exchanges of many connections which have to ring many phones at the same time. A source of signal exist and is connected to the phone that has to ring. In such configuration it is just to program the sequence of connections- that's all.

Have fun

Stanislaw.

Reply to
Stanislaw Flatto

According to the telephone specs, 16V AC (21V peak-peak) should make a telephone ring.

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Reply to
Nico Coesel

Do you have to make all 24 telephones ring at once or switched?

What is your exact requirement in this case.

Joe

Reply to
Joe G (Home)

Almost any :-) You just have to add a mains transformer, connected in reverse. Connect the transformers output to the amplifier's speaker output. Obtain the ring-voltage from the wires that where intended to carry 'mains'. Use some appropriate voltage ratio, e.g. 10 to 115 Volt or 24 to

230 Volt.

Keep in mind, that your ringer signal probably is -- or should be-- 25 Hz. As the average transformer is intended for 50 / 60 Hz, don't load the transformer to more than say 30% of it's rated power.

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Kind regards,
Gerard Bok
Reply to
Gerard Bok

You need 96 VAC at 25 Hz.

You can take a 50 Watt audio amp, and connect an audio test generator up to it as a source oscillator in series with a push button switch.

You can get a 120 Volt to 12 Volt power transformer, rated to at least 3 amps, and connect it up as a step up transformer on the output of the audio amplifier. Across the output of the amplifier in parallel to the transformer, put a 27 ohm 20 Watt resistor across the output terminals to give the amplifier a resistive termination load.

Before connecting up the phones, put a true RMS DVM across the secondary of the 120 Volt side of the transformer that is going to drive the phones. Set the audio generator for 25 Hz, with a level that is adequate to drive the input of the amplifier. Send the signal to the amplifier. On the output side, adjust the volume control so that your DVM reads 96 to 98 VAC.

Now you can connect the phones as you wish. Your phones should ring just as if they were connected to a telephone line.

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JANA
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Reply to
JANA

Hi ! Should I use a bridged amplifier, or simply a mono amplifier ? I will try that trick with the 50W amplifier.

Thanks a lot !

a
Reply to
aalex

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