27 Apr 2011

Mains hum powered beacon

Recent tests with earth electrodes at VLF have got me wondering about a simple QRSS HF/VHF beacon TX powered entirely from the rectified mains hum and other crud coming from a couple of earth rods in the ground.  Not sure of the available power, but I suspect it would be in the 0.1 to 2uW region, maybe more. This may be enough to drive a low voltage QRSS beacon for example. You can buy power harvester ICs these days for this purpose, but with a step-up mains transformer there may be a volt or two available at a few tens of uA and that alone may be enough to drive a keyed oscillator. The ultimate in free power beaconing!

1 comment:

David said...

Several years ago EPE published a circuit using a quad bilateral switch and some discretes as a "Forever Flasher" powered by mains pickup from a wire.

I built it and still have the LED flashing away all this time later. I can probably dig up a PDF of the article if you're interested.

- Dave G7UVW