[aprssig] Wanted: tone-based reset module schematics

Wes Johnston aprs at kd4rdb.com
Tue Feb 7 10:09:31 EST 2006

I can see that you'd want to know when or how often it resets... so when
you design around your failsafe... when the 555 timer times out and
asserts the reset, have it assert the reset for 5 seconds, and during
that time, have it play a 1khz tone and key the PTT.  When you hear the
5 second beep on air, you know it has reset.  Not that anyone actually
listens to packet channels for extended periods.  Alought I sometimes
decode psk31 by ear for fun... lol.

Seriously, another way to keep tabs on resets would be to get an electro
mechanical counter (one pulse per count) and hook that to your reset
line.  Then when you visit the site you can see how many times it reset
since your last visit.


Brad [VE3BSM] wrote:
> Many thanks for all the replies. The timer-based solution has a good
> advantage of not requiring any specific intervention, like somebody having
> to notice the digi isn't digi'ing and do the tone(s). I'd definitely prefer
> an approach that hooks to the PTT line than into the RF. I can see
> monitoring actual RF is more robust (like if the radio itself fails into
> TX), I want something that doesn't require opening the radio itself or tying
> into the antenna feed. In many cases, our digis are installed in commercial
> radio sites and in a few share an antenna with other stuff. If I don't have
> to touch anything on that end, I won't risk worrying the site owners.
> That DTMF decoder sure looks cool though. There's definitely the "nerd
> factor" of something like that. :-)
> X-10 isn't a viable solution. For one thing, if I have to hike 44 minutes to
> get within X-10 range, I might as well hike the extra 1 minute to the actual
> door and walk in. None of the sites have PCs or accessible phone lines. The
> Lamp/Appliance timer would be a possible poor-man's solution, though in my
> experience if you use these in rough (ie. Cold) environments I'd have to
> worry about the timer failing. If I buy a good timer, I might as well
> splurge for the DTMF decoder.
> That Mister-House thing looks cool. I'm going to have to look closely at
> that for some other projects I'm playing with.
> Brad.
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