[aprssig] Solar Powered Digi
bruninga at usna.edu
Thu Dec 23 09:44:36 CST 2004
Normally a power-saver circuit kicks back in in only 5 seconds.
So you would have to have an external 555 to get any
decent time out of it... bob
>>> Wes Johnston <wes at kd4rdb.com> 12/22/04 2:00:53 PM >>>
I was thinking about something like this the other day.... a solar digi
the swamp between my home and work - No, I'm not shrek, I don't LIVE in
My idea was to put and HT in the digi because of it's power saver
144.99-600. Now, ordinarily the power saver would prevent the HT from
the first part of a packet. The trick here is that since there isn't
traffic on 144.99, if the HT just caught the tail end of a packet, it
enough to kick it out of power saver mode. Then when the next packet
along, if the power saver hadn't kicked in again, the digi would hear
Another thing that will kick an HT out of power saver mode is to open
squelch. The trick is to have watch the DCD LED on the TNC, and if a
triggered the DCD LED for say 100mS (easily done with a kpc3plus), then
a 555 timer (you thought I was going to say basic stamp, didn't you?)
force the squelch open on the HT for say 120seconds. This I think
could be done
by simply shunting across the "bottom" of the squelch pot on the HT.
two thin wires hanging out the case running to an optoisolator (ie
Could probably get by with a FET, 100uF cap and a 1M'ish resistor too.
What makes this work is that as I approach the digi, it hears my
not good enough to decode. So chances are that the first packet it
would not have decoded anyway - but that was enough to wake up the
digipeater". After that it keeps listening for 2 minutes after I'm out
Quoting Robert Bruninga <bruninga at usna.edu>:
> A real power-saver on SOlar Powered Digis:
> If you need a digi in an area, but cannot afford the huge
> solar power system to keep it on the air most of the
> time, consider making it an ALT-INPUT digi on 144.99
> instead of a full service digi on 144.39.
> The TX load will be 2 to 5% of what it would be if the
> input was on 144.39 because it will only digipeat
> the locals that need it, and not the 98% of other
> digipeater traffic coming at it from all directions.
> Your digi will listen on 144.99 for locals and low power
> trackers (probably fewer than a dozen) but will still
> digipeat them over to 144.39 to join the network.
> Just a thought for some special applications...
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