"David Nebenzahl"

Skimming through a bunch of ESR meter schematics, this seems to be the
game plan for most of them:

Oscillator -- attenuator -- cap under test --
op amp/comparator -- rectifier -- meter

(osc. is usually around 50-100 kHz)


(the attenuator delivers only millivolts to the cap being tested, avoiding
electrolytic polarity issues and any semiconductor junction resistances)


** The idea of including an "attenuator " is misleading.

The electro under test needs to be driven with a known *current* at
00kHz - 20 to 50 mA is good.

Simply shorting my bench audio generator with the output level set to max
produces 29.7 mV into a 1 ohm resistor at 100kHz or 30mA, near enough.

If the electro under test has an ESR of 100 milliohms - the above set up
produces 3 mV rms across the cap which is easily enough viewed on most
scopes.

Long as you connect the scope direct to the leads of the electro and know
the current level from the generator - actual ESR values can be found.


..... Phil