![]() Still, a nice little project if you have a way to program up a Mega328. I matched the 680r and 470k resistors to the third digit, maybe better matching would help. A 0.01% 5k resistor reads 5066, so about 1.3% which is good enough for a quick test. Just tested the accuracy of my home made version. ![]() Anyway, a cute little gizmo, certainly worth the $20 and it seems reasonably accurate within the scope of it's limitations. A 100nF capacitor is required at one point (step 4, IIRC). On-screen directions kind of guide you through each numbered step if you scratch your head long enough deciphering them. I accidentally discovered a self-test/calibration mode by connecting all 3 leads to each other and pushing the button. That really IS a diode that got mixed in with the SCRs - look at the number: Ok, here's a real SCR (GAC indicates which lead connected to the Gate, Anode and Cathode, respectively): But an LM317 threw it for a loop: The documentation is non-existent. Oh well, at least I can figure out from that if it's PNP or NPN: FAIL again - Ooops, no it's not. This is a power transistor, not a pair of diodes. (To be fair, it's rated 600v/40amps): Partial Fail. It tells you what it is and the value: A 1% resistor: A capacitor (this one must have real low ESR - usually there's a value in ohms): A transistor (note that it tells you if it's PNP or NPN and which lead is connected to what, gain and forward voltage): How about an inductive load? FAIL! That's an IGBT, not a capacitor. Operation is simple: connect the component (leads in any order), push test. I put it in a project box, added some leads and a switch and hooked up a 9v battery. What the heck, for $20 it looked like it could be fun, especially for a dilettante like me with a drawer full of oddball small signal mystery transistors. ![]() A few weeks ago I stumbled over this fellow on fleabay.
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