incorrect reading on multimeter with capacitor

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dksucharda

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I am new to electronics. I have an Aneng AN8008 multimeter. I have been using it to test volts and resistance and everything is fine. I am building one of the Elencon FM radio kits to get my feet wet. I am about 2/3 of the way done and am getting ready to solder in some discaps. the multimeter tests in Nanoferrads but a lot of the capacitors I am testing are in Picoferrads; no big deal, just move the decimal. But my concern is the multimeter seems to be giving out very different numbers than what the capacitors are speced at. These capacitors are al discaps. Before testing them I have discharged them. some are even reading Zero. multi meter seems to work on ohms and voltage just not for capacitors. I don't know if the capacitors are bad or the meter. The meter is basically brand new but I realize it isn't a high end meter. Not sure if anyone can help but would appreciate suggestions.
 
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Ceramics have a strong V dependence on their C. So depends on the 8008 mehtod its
using to measure C.

Does the capacitance change when a DC voltage is applied to ceramic capacitors? Are there any points to be aware of regarding changes in the capacitance? | Capacitors FAQ | Murata Manufacturing Co., Ltd.

Murata's Products. - Ceramic Capacitors (Characteristics) FAQ No.0005
www.murata.com




Ceramic capacitor - Wikipedia

en.wikipedia.org

I have a couple of 8008, there are mods you can do to imrove measurment settling time

Aneng AN8008/AN8009 Modify For Better Accuracy Faster Readings – JackenHack

The Aneng AN8008 is a great Multimeter. Unfortunately it takes around 5 seconds for it to stabilize when measuring. Here's a simple modification to fix it.
www.jackenhack.com


A Few Caps For A Faster Multimeter

We just love it when someone takes apart a bench instrument. There is something about voiding a warranty and then making modifications that hits the spot and in a series of simple modifications, [J…
hackaday.com


Regards, Dana.
 
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PicoFarads are extremely small. Unplug the leads of your multimeter so that you can measure the capacitance of its input. Mine measures 0.15nF which is 150pF. I cannot cancel that capacitance then it will be an error.
Now plug in the leads and see the added capacitance between them. My measurement has many changing numbers from 330pF to 560pF which is an error when measuring pF capacitors.
 
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Consider selecting/obtaining capacitors that will be used as reference against your own instrument. When in doubt of a reading, probe the ones you are sure about their value. Perhaps some day you will migrate to an instrument that will make you more confident.
 
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Thank you all for your response. I did test some of my "larger" capacitors and it seems meter is better with these. The microfarad capacitors seem to be easier for meter to read. Some information above is above what I able to make sense of but appreciated all the same. It is all exposure and I will learn more over time. Audioguru: I think I understand the general premise of what you are saying and I think this may be at the root of my issue. Thank you. And yes, ZipZapOuch, I should probably trust the labels and build the radio. I think the testing was part of part of the learning but not to the point of paralysis. Still need to finish the project. Thank you all. Back to soldering. What is the worst that can occur.
 
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