On Thursday, May 28, 2020 at 3:55:50 PM UTC-4, Ralph Mowery wrote:
Today I received one of the roughly $ 20 component testers. Checking
it out and comparing capacitors I notices a big difference in a couple
of them

I was using a Fluke 87, a LCR meter from China, an older component
tester and the new component tester.

The first capacitor was a Sprague .06 uF 600V. Two China testers showed
near the value. Within the 10% tollorence, The LCR tester showed it
to be .08 and the Fluke as .1 uF.
This is a new,but very old capacitor.

Next capacitor was a 20 year old no name of .068 of 50 V made with the
Poly something dielectric. All meters were with in less than 10 %. Ok
here.
Same results with a newer one of .01 uF .

Next came a Silver mica. It is .01 at 600 V. Fluke shows up at .0150,
LCR at .0120. Two component testers were close and in spec.


What gives with some capacitors checking like they should and some being
way off, not just 10 % or so ? I ran the tests several times on each
capacitor to see if maybe the leads were not making good contact and any
other similar thing I may have missed like having my fingers across the
leads.

Ralph ku4pt

I think it would be nice to have a dedicated capacitor checker to verify everything.

I have a one of the mega328 Chinese component checkers and compared to a Sencore LC75, it's pretty close on capacitor values as long as the capacitors don't have any leakage. If there's any leakage, the values are skewed. The other odd thing is that the 328 will return different results depending on what combination of terminals 1, 2, or 3 are used, which is odd.

Compared to the Sencore and an EDS88A ESR meter, the 328 component tester is good enough to trust with ESR.

The 328 is pretty good with resistances as long as it's over an ohm. Anything under an ohm is a waste of time. For low value resistors, I use one of my Fluke DMMs.

The 328 component tester is also not very accurate on inductances. For inductance, I use the Sencore LC75.