stamasd wrote:keropi wrote:Strange, once off-circuit you should be able to get accurate readings... maybe the tool you are using to measure is acting up?
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Strange, once off-circuit you should be able to get accurate readings... maybe the tool you are using to measure is acting up?
I could never get good capacitor measurements with my digital multimeter , every other function is OK but the capacitance function is a mystery to me. On the other hand one of these cheap eBay "capacitor meters" work really good to measure capacitance. Since I got one I never tried the digital multimeter way again...
Yes I highly recommend that device. It's great for measuring all sorts of components. It even does JFET and MOSFET transistors with the appropriate firmware (which is open-source BTW).
For measuring capacitors it pays to use as short connection wires as possible; best is to plug the capacitor directly into the socket. This way you keep stray capacitances and inductances to a minimum.
If it hasn't been mentioned, measuring "large" (hundreds of uF) capacitance values is not easy to do with smaller, low voltage meters. Most of these devices use a simple RC time-constant measurement process, and the long time constant of these capacitors causes problems for devices that use coin cells or similar for a power source. Basically, the capacitor accepts charge faster than the battery can source it.
For reliable testing of high-value, low ESR caps, you need a beefier tester, or one that employs smarter charging/sampling methods. Hope this helps.
