OT: touch-tone phones, was Re: Beehive terminals

[Brent Hilpert]

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
> schematic.

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.

http://www3.telus.net/~bhilpert/tmp/touchTone1969.gif

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.