Yet another use for a curve tracer

Ed Breya

I've been cleaning up and organizing lots of stuff lately, and I found I had a couple dozen various AC light dimmers and fan controls piled up. After I eliminated the obvious junkers - marked bad, taken apart, busted parts, etc - I had about a dozen left, to save for possible re-use. I decided to check them out on the curve tracer, to eliminate any more bad ones from stock.

I set up the 576 for AC, 350 V peak range, series R 680 ohms, H 50 V/div, V 100 mA/div, and started testing. It worked great, and all of the two-terminal types checked OK. There are some three- and four-terminal ones that need further study to figure out appropriate hookup. Here's the process, for two-terminal types:

1. Set collector supply to zero.
2. Hook up dimmer.
3 Set collector to about 175 V peak.
4. Run dimmer knob through OFF and full range.
5. Display appearance should change according to dimmer setting, from a flat line or small "+" to a large "+," indicating proper operation.
6. Turn collector back to zero.
7. Disconnect dimmer, and connect the next one.
Repeat as needed.


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