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$20 LCR ESR Transistor checker project

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A few weeks ago I stumbled over this fellow on fleabay:


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. I put it in a project box, added some leads and a switch and hooked up a 9v battery.  Operation is simple: connect the component (leads in any order),  push test. 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. (To be fair, it's rated 600v/40amps):

Partial Fail. This is a power transistor, not a pair of diodes. Oh well, at least I can figure out from that if it's PNP or NPN:

FAIL again -- Ooops, no it's not. My mistake. 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. I accidentally discovered a self-test/calibration mode by connecting all 3 leads to each other and pushing the button. On-screen directions kind of guide you through each numbered step if you scratch your head long enough deciphering them. A 100nF capacitor is required at one point (step 4, IIRC).

Anyway, a cute little gizmo, certainly worth the $20 and it seems reasonably accurate within the scope of it's limitations.

Could you give a few more capacitors a try to see if it actually can measure ESR. What is the test voltage for capacitors?

I remember seeing the exact same thing on eirik Taylors blog on 4hv. It had pretty good documentation and test results on it so you might want to go check that out

I looked for the review or blog and got nowhere. A link please?

Analogtech: that's the link to the blog


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