Yes ... another ESR meter.

[taiteki]

Hi!  i am working in an ESR meter. I will use in circuit meter.

I hope someone could help me in a cuestion.

The voltage over de capacitor under test is 75 mV Vp, 150mV Vpp.

In the case of an 1N5822 (Von = 0,115 V) works fine.

Can i increase the voltage, or 150mV is ok? 






Thx! and sorry for my english.

[w2aew]

Small mistake in your schematic?  Looks like you have the op amp inputs reversed.  If you're getting enough sensitivity/resolution with the small drive, then there's no reason to increase it.  One difference between this design and others I've seen is that your test signal applies a bipolar signal to the capacitor, which will momentarily change the polarity on electrolytic caps.  Many other designs use a unipolar squarewave drive signal so that the capacitor under test doesn't get reverse biased.

[taiteki]

  sorry ...  fixed.

Yes there are a reverse biased. I will search about that.
I hope that don´t affect the capacitors.

the ESR only can measure form 0,02 to 3 ohm.

thx!, Fran.

[dannyf]

I hope that don´t affect the capacitors.

The only capacitors that are sensitive to reverse polarity are tantalum and super caps. Tantalum, even when briefly exposed to reverse (DC) polarity, can be damaged and often time go into flame / explode.