[aprssig] New OpenTracker variant available

scott at opentrac.org scott at opentrac.org
Tue Aug 1 22:15:10 CDT 2006

The OT1m boards have been in beta for awhile, but the cases are finally done
and I'm now selling assembled units.  Kits will follow next week sometime,
when I get the assembly documentation finished.


I designed this version of the board when I discovered that the small size
of the regular one can really be a hindrance for some applications.  Power
control, for example, has always been a bit of a pain.  The OT1 can output a
signal to turn the radio on and off, but it needed an external circuit to
actually control the power.  The OT1m has space for a 9 or 20 amp switch IC,
plus holes on the board that'll accept up to 12 AWG leads.  It's meant for
short duty cycles, but I've run a 60 watt mobile at high power for a solid
minute and it wasn't in danger of overheating.

It works great for solar powered weather stations - it'll connect to a
1-wire weather station with standard telephone cable, and with the radio
powered off draws under 10 mA.  I'll probably offer an LDO regulator option
later, which shaves 3 or 4 mA from that.

Beware, the audio tops out at a much higher level than previous boards.  It
should drive just about any rig without modification, but for HTs especially
you'll want to turn down the audio level in software, and fine tune it using
the pot, to keep from overdeviating.

Oh, the power supply will current limit at about 750 mA.  Shouldn't keep it
from driving any sane GPS receiver, and it's already saved a couple of test
units from accidental magic smoke release.  Also, the counter input is
present on the modular jack.  You can wire it to a pushbutton (or any other
contact closure device) and count runners passing your location in a
marathon, repeater transmissions since last beacon, or whatever.

The 20 gauge steel enclosure should also be more resistant to the
getting-run-over-by-a-car failure mode that a couple of OpenTrackers have
experienced.  ;]

Scott, N1VG

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