Quick Multimeter Trick for Measuring Small Capacitors

[FuzzTony]

Hi folks, thought I'd share something I just discovered.

I wanted to verify the values of some Tayda ceramic caps (10pF - 100pF range)  but my multimeter is not very accurate in that range.  47pFs were measuring at about 20p.  1nF and higher it has no problem and is accurate.

I thought about ordering a dedicated Capacitance Meter, but then I discovered a little trick.

I got accurate results for those small values by testing them in parallel with a box cap around 1nF. 

Easiest for my setup is to use a breadboard with a 1nF cap across the multimeter leads, and then hit the "relative" button to zero it out.  I can then plug & unplug my little ceramics into the breadboard to my heart's content, and am getting accurate measurements.  Try it!

I just wanted to share this because I did not find any such suggestion in my online searching, only references to the unreliability of most multimeters in this low range.  The DIY solutions I did find were quite complex.  Cheers!

[culturejam]

That's a neat trick. I don't think any of my meters have a "zero" function, however. So I think you could get the same result by measuring the 1n cap first and then adding the other cap in parallel to see the change.

[pickdropper]

Yep, good advice.  I need to use the relative function on my Fluke 8 IV to get reasonable measurements of low value caps.  It's not as good as an LCR meter, but it is good enough to get by.