OT: touch-tone phones, was Re: Beehive terminals
hilpert at cs.ubc.ca
Sat Dec 31 21:40:48 CST 2005
der Mouse wrote:
> I don't think
> curiosity is worth risking breaking the one really good DTMF phone I
> have, so I can't trace my circuit to tell how well it matches your
Well, I was curious: here's the schematic of my 'main' phone, an
Automatic Electric touch-tone from 1969.
... makes a little more sense than the Bell schematic.
You can see the one transistor formed into an oscillator
with two resonant circuits. I too was rather surprised/amused
at it's simplicity when I RE'd it.
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