Re: Generating a 20hz 90v signal phone ringer
- From: fmmck@xxxxxxx (Fred McKenzie)
- Date: Thu, 13 Oct 2005 14:16:54 -0400
In article <7eWdnQn3ls6JhNPeRVnyjg@xxxxxxxxx>, "Dave D"
<dave_d@xxxxxxxxxx> wrote:
> 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-
This sounds like it will probably work OK. My concern is that a 60 Hz
power transformer may have much too low of an impedance at 20 Hz.
The 555 circuit is probably stable enough for a resonant bell. There is
also the Rube Goldberg approach: One could divide the 60 Hz power line
frequency by 3. For battery-only, there is a chip that divides a 3.579545
crystal (tuned for 3.579540) to produce 60 Hz.
Fred
.
- References:
- Generating a 20hz 90v signal phone ringer
- From: Michael Kennedy
- Re: Generating a 20hz 90v signal phone ringer
- From: Dave D
- Generating a 20hz 90v signal phone ringer
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