Here are two options for semiconductor analysis:
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.
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.
So I got myself this new bit of kit: M328 Diode Triode Capacitor Resistor Transistor ESR Meter Multi-Function Tester. When I opened the box there was no manual. But it turns out a manual is not required! This thing is so easy to use. Just wire up any old component and the device will tell you what it is!