[aprssig] Wanted: tone-based reset module schematics

Andy AB9FX ab9fx at aprs.pl
Mon Feb 6 22:22:40 EST 2006

There is some project with DTMF control (reset TNC and more) working with SP6VGA-2 digi by SQ6ADE.
Comments are in Polish, so if you are interested in it, I can do translation for you.

  ----- Original Message ----- 
  From: Brad [VE3BSM] 
  To: 'TAPR APRS Mailing List' 
  Sent: Monday, February 06, 2006 18:56
  Subject: [aprssig] Wanted: tone-based reset module schematics

  One of the digipeaters I upgraded to UIDIGI last summer had a small circuit card mounted in the TNC. I didn't pay much attention at the time, but it turns out to be a small reset circuit for the TNC. Basically, it listens on the audio input for a specific tone for 2 seconds, at which point it trips the reset line of the TNC. It's used to recover from a severe lockup of the TNC (which it turns out UIDIGI sometimes suffers from). I had to use it once recently and it saved me from a miserable hike up a snow-covered mountain.

  I'd like to come up with something similar for the other digis I maintain. But I haven't yet found any schematics for anything *simple* that does the trick. I'm hoping maybe somebody here has some schematics, or a pointer to a site with some.

  Failing that, when Spring comes I'll hike up the mountain and reverse-engineer what's up there, though that's not exactly my strong suit.

  Emphasis on the "simple". This one uses a single tone and I seem to recall it had one IC (maybe two) and only a couple of discreet components. A DTMF decoder would do the trick (and be less prone to spurious resets, presumably), but I really don't have the ability to get into PIC-based designs.

  Anybody seen anything like this?



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