Re-installing a TouchTone keypad in an ASR-33
cclist at sydex.com
Mon May 18 16:04:33 CDT 2009
On 18 May 2009 at 16:17, Dave McGuire wrote:
> Oh, how thoroughly bizarre. Thanks for the explanation. I'd love
> to see a SPICE simulation of that.
What's noteworthy is the stability of the thing. ISTR that DTMF
signalling relies on a tolerance of something like +/-2%. A mass-
produced LC oscillator that operates reliably close to tolerances in
a steel mill or a meat-packing plant is a marvel.
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