Category Archives: Electronics

Continuity tester

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I had a suspected short circuit in a cable I made (I think I used too much heat on the heat shrink and caused insulation to melt) and what I needed was a continuity tester. My multimeter is bollocks for continuity so I knocked together my own:


I used a green 5mm LED, a 68 ohm resistor, two AA batteries, some banana sockets, and a bit of wire. I used my rotary tool with drill bit, burr, and countersink to score the holes in the case.

I used this LED Resistor Calculator to figure out the resistor rating (~50 ohms). I used my M328 Multi-Function Tester to figure out the forward voltage across my LED (it was 2.1 V, the default).

p.s. the cable under test was shorted! Turns out its a bad idea to put heat shrink tubing over electrical tape! And now we know.

I made a cable!

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Been pottering in my lab:

I have this USB Logic Analyzer which I want to test:

Figured this was a great chance to try out my new XR2206 function generator:

Hmm. Needs power! The XR2206 datasheet said it could support a wide supply range, from 10V to 26V. Figured this was a good chance to try out my new ATX power break out board:

I need a power cable from round lugs on the ATX supply:


to DC male for the function generator:

connected with a good length of wire:

and professionally finished with heat-shrink tubing:

had to break out my soldering station:

and make myself a power cable:

to connect the ATX power supply:

to the function generator:

Testing the logic analyzer can wait for another day. :)