hi all, i recently finished building a esr meter. i zero the meter then when i read a cap the reading goes past zero? can someone help?

 

Isn’t that what it should do?

Are you complaining about the 0 reading with nothing connected?

 

Isn’t that what it should do?

Are you complaining about the 0 reading with nothing connected?

no, the reading of the cap should not go past the zero point..the meter is zeroed with test leads shorted.

 

the reading of the cap should not go past the zero point..

It all depends on what capacitors and what resolution of your meter.

 

no, the reading of the cap should not go past the zero point..the meter is zeroed with test leads shorted.

Residual charge in the cap ?

High value electrolytic caps are especially bad for this and should be held shorted immediately prior to testing.
Even after shorting leave them a while on the bench and voltage can grow again.

 

Hi pete,
Post the esr circuit.
E

 

 

hi this is the circuit. i didn't have a lm324 so i used a tl084. i the 84 has too much gain?

 

hi this is the circuit. i didn't have a lm324 so i used a tl084. i the 84 has too much gain?

BS. The amount of gain is controlled by the external components.

 

hi this is the circuit. i didn't have a lm324 so i used a tl084. i the 84 has too much gain?

In structure, these are different op-amps.
LM324 -industry-standardoperational amplifiers.TL084-FET-Input Operational Amplifiers.
LM324.
GBW-1.2MHz.
SR-0.5.
TL084.
GBW-3MHz.
SR-20.
The original circuit used TL084.
https://www.qsl.net/iz7ath/web/02_brew/15_lab/06_esr/index.htm
There is some good information here. Test your circuit to make sure it is working correctly.
https://www.vintage-radio.net/forum/showthread.php?t=56933

 

In structure, these are different op-amps.
LM324 -industry-standardoperational amplifiers.TL084-FET-Input Operational Amplifiers.
LM324.
GBW-1.2MHz.
SR-0.5.
TL084.
GBW-3MHz.
SR-20.
The original circuit used TL084.
https://www.qsl.net/iz7ath/web/02_brew/15_lab/06_esr/index.htm
There is some good information here. Test your circuit to make sure it is working correctly.
https://www.vintage-radio.net/forum/showthread.php?t=56933

thanks guys. i'am going to increase the value of r13/r14 to 1.5k.

 

RE:"" i recently finished building a esr meter. ""

Have no a least wish to kill Your satisfaction or enthusiasm, but what may be a rationale to spend few days or maybe a week to solder a device what factory made in shops like ebay or AliExpr cost between 3 qnd 10 USD. For me, only if I am totally unsatisfied with factory made sensitivity. Yet I am not quite sure Your construction is any better. Or I miss something?