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Capacitor ESR Meter 2012-01-27

What is ESR and How Can It be Tested?

As the allmighty Samuel M. Goldwasser says, "ESR (Equivalent Series Resistance) is an important parameter of any capacitor. It represents the effective resistance resulting from the combination of wiring, internal connections, plates, and electrolyte (in an electrolytic capacitor). The ESR affects the performance of tuned circuits (high ESR reduces the Q factor) and may result in totally incorrect or unstable operation of devices like switchmode power supplies and deflection circuits in TVs and monitors"

"When troubleshooting electronic equipment, electrolytic capacitors, in particular, may degrade resulting in a significant and unacceptable increase in ESR without a similar reduction in uF capacity when measured on a typical DMM's capacitance scale or even a cheap LCR meter."

Of course, dominating the classic capacitor testing techniques is a must (Here's a link about that). But testing the ESR may explain erratic ircuit working or predict future failures.

Now that we know the ESR importance, how can it be measured?
This circuit (by Gary Woods) measures ESR without desoldering the component. His website is down, but fortunetly I've saved a copy


1) Schematic (.gif)
2) Parts List, Circuit explanation, Funny operation instructions (.txt)

I'll attach more circuits as I find them.

Your feedback and contributions about this and other circuits would be very appreciated by everyone.
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