Re-installing a TouchTone keypad in an ASR-33

Brent Hilpert hilpert at
Wed May 20 17:23:06 CDT 2009

Ethan Dicks wrote:
> If it's an ITT or other non-Western Electric phone, I'd wager it's
> IC-based.  AFAIK, only the W-E phones (i.e., pre-breakup) would have
> the 1-transistor-2-coil keypad.

As indicated in my previous message on the topic, Automatic Electric was
producing a 1-transistor DTMF design in the 60/70's, almost identical to WE's.


I don't know what it was like in the Bell/WE regions, but out here DTMF, while
available, didn't really take off until sometime in the late 70's/80's I would
say, perhaps in correlation with the switch to IC-based DTMF. I'm guessing the
number of 1-transistor DTMF phones produced was relatively small,
(particularly) compared to the number of dial phones produced in the same time period.

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