Re: Generating a 20hz 90v signal phone ringer


"Michael Kennedy" <Mikek400@xxxxxxxxxxxxxxxxxxx> wrote in message
news:qf2dnVFyr_bJZdDeRVn-hQ@xxxxxxxxxxxxxx
> I'm trying to make a telephone ringer. What would be a good way to
> generate a 20hz 90v signal. I can handle the 90v part no problem but the
> 20hz is an issue. I have had thoughts of hacking one of those analog
> telephone adapters (ata) for Voip service to do this. It could probably be
> programmed to ring when a certain number is dialed.
>
> Any Ideas?
>

Very easy. A small 120v transformer with, say, a 12v secondary. Drive the
secondary with a lower voltage AC waveform than 12v to get approx 90v out.
You could use a transistor driven by a 555 timer IC running in astable mode
at 20Hz to drive the transformer. The positive rail if the 'inverter'
circuit could be supplied by a simple adjustable regulator to get the 90v
out from the transformer.

Obviously the transformer will not be very efficient at 20Hz, but it will
work well enough for this application.

Dave


.

Relevant Pages

  • Re: Generating a 20hz 90v signal phone ringer
    ... > I'm trying to make a telephone ringer. ... I have had thoughts of hacking one of those ... Simple way is an oscillator generating an approx sine wave feeding a pair ... be triggered by a logic circuit to give the ring cycle as required. ...
    (sci.electronics.repair)
  • Re: Power Transformer Requirements...
    ... Spec at Torres among other places. ... Do I understand that you require approx. ... The current transformer is already giving me ...
    (alt.guitar.amps)
  • Re: Space Shuttle voltage problem
    ... I  have a voltage problem at the input of the flipper board. ... then I have a bad transformer #2. ... powers only that connector. ... transformer and good BR with no other faults should read approx 48V AC ...
    (rec.games.pinball)