On Tue, 28 Mar 2006 17:00:19 +0100, "Dave D"
wrote:


"Michael Kennedy" wrote in message
...
there are little circuit boxes that immitate the phone line, last I saw
one about 60 bucks

Sounds good, but so far the cheapest one was 114 plus S&H. Maybe I'll
find the model you saw.

Thats the way to go... Getting the operating voltage (48vdc) isn't that
hard just hook up 4 12 volt batteries in series with an 800 ohm (If I

I can handle this.

remember correctly) reisistor on the end. Getting a 20hz ringtone is the
difficult part since the wall current is 60hz.. I never figured out an
easy way to make my phones ring.

- Mike


This sounds good, but I need to have it explained in simpler words.

There's several easy ways to generate a 25Hz at 96v, one is an old
fashioned multivibrator driving a 120V/12V transformer secondary, (ie a 25Hz

Multivibrator?

inverter)

25Hz inverter. All I can think of is the power supply from a tube
radio in a 1950 car, that runs off a 6 (or 12) volt battery.

and adjusting the multivibrator's supply down to get 96V. It's
rough and ready but there's no reason why it shouldn't work, and it uses a
few standard, off the shelf components.

So I have to build it? I can do that but I don't know how.

Dave



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