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N0ZYC 12v DC load:




Decades ago I built a load tester from scratch. I started with a modest size aluminum project box and installed
a bunch of 12v brake lights, which turned out to be a really good load. Each of these lights had two filaments,
each of which drew almost exactly 2 amps, and the lights were cheap. I used solid copper wire as a framework
to wire things together, and installed toggle switches on the top to cut in 2, 4, 8, and 16 amps, as well as having
a variac that could add in a fine amount between 0.5 and 2 amps. I didn't have a switch rated for 16 amps so I
used a smaller switch to drive an automotive relay for that. For measuring current, I just looped about 5 feet
of insulated #1 wire around inside as a shunt.

I also attached a simple (analog) meter and a switch that would change it between displaying volts and amps.
So for under $20 plus some scraps, I had built a variable 12v load that could handle 0.5 to 31 amps, which was
plenty for testing power supplies. (and I still use it from time to time even today) That poor relay, it got its
case melted like ice creme, but it still works!

closed	inside high	inside low close	inside low	other side

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last updated 05/15/2025 at 21:59:05 by make_www_index.command version 2025.05.13.A