The NoGa PiG (Power indicator and Guard)
This kit from the North Georgia QRP Club goes way beyond the category of a handy QRP accessory. The PiG
provides protection against reverse power connection, overload/short
circuit, crowbar protection against overvoltage should your power supply
regulator fail, and indication of low voltage from your battery pack. The
circuit board also supports the optional addition of a PIC-based 8-pin
DIP keyer and a passive audio hiss reduction circuit. So far, mine is the
basic PiG. (Note: the Altoids box and custom artwork are not part of the
kit, they're my own design).
While troubleshooting one of my homebrew projects, I blew the fuse from
my battery four times and temporarily gave up. Those 5mm fuses aren't
cheap at RadioShack. I mentioned the problem at a NoGa meeting in the
summer of 2005, and a club member said,"Why don't you just finish your
PiG? You won't need any more fuses." I'd had the kit for a couple of
years and just hadn't gotten around to building it. The trip current for the resettable
Polyfuse in the PiG is 2.7 amps, with a hold current of 1.35 amps. It will isolate the
circuit and sink the
over-current. After you disconnect the faulty circuit, the Polyfuse cools
and resets.
I have standardized all of my DC power around Anderson PowerPoles. I have
DC input pigtails made up for battery lugs, bare wire ends and 2.1 mm
center-positive coaxial plugs. So far, I have DC out pigtails for 2.1 mm
and 2.5 mm coaxial plugs.
Further information on the NoGa PiG is available on the NoGa site