ESR Meter

214

01:52:39

Equivalent Series Resistance Meter
http://ludens.cl/Electron/esr/esr.html

from left to right:
square wave oscillator
impedance converting transformer
capacitor under test
proportional amplifier
rectifier doubler
adjustment pot
galvanometer


output of the oscillator goes through the transformer and gets shoved through the capacitor being tested.  the output from this capacitor is a triangle wave.  the amount of ESR in the capacitor determines the amplitude of the triangle. Lower ESR gives a bigger amplitude.  it's only a tiny amount if difference, but it makes a big difference at the end of the rectifier.  the result is a current indicative of the amount of ESR through in the circuit.

published 10 years ago

giomix

10 years ago

Very nice projects at the links, thanks.

alexmayorov

10 years ago

In the original circuit a signal at first 10 Ohm resistor (secondary winding of transformer) is square wave, not triangle (as in the circuit). To correct regime one needs change transformer parameters (primary turns = 400, secondary turns = 20, coupling coefficient = 0.95, primary induction = 20 mH). Then current will be about 50 uA with ESR=100 mOhm.

faceblast

10 years ago

thanks Alex, you are correct and that's closer to what I'm seeing on my cro as well, even though my transformer is measuring 150mH

hurz

10 years ago

Probably better to go down in frequency from 82kHz to 8.2kHz for your used transformer, and adapting the circuit.

faceblast

10 years ago

but the tl062cn is only capable of 200μA so I need at least 100mH at 50kHz to give it 25kΩ impedance

faceblast

10 years ago

dropping the frequency to 10kHz lowers the impedance to 10kΩ and this opamp can't drive it

hurz

10 years ago

Oh what a 200uA gay OpAmp. So spend an emitter follower bjt.

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