How to measure capacitor with a basic digital multimeter?

[KimmoSWM]

I need help from peopple understanding better these things. So, I would like to measure for example the capacitance of some capacitor. How should I do that? How about tolerance, is it even possible? What about resistors, how to measure the resistance and tolerance?

Thank you in advance for helping me stupid..

-Kimmo-

[richie00boy]

Most basic multimeters cannot measure capacitance. They do amps, volts and ohms.

[vacuphile]

A multimeter measures what the capacitance is, or the resistance. If you measure enough of similar ones and know what value is they are branded, you know the tolerance of the batch.

vac

[sofaspud]

You can measure larger value caps with a 12.6V or 6.3V filament transformer, an AC voltmeter, and a 50k potentiometer. Put the R and C in series with the secondary and apply mains voltage to the transformer primary. Adjust the pot until the voltage drops across the R and C are equal. Disconnect and measure the resistance of the pot. Then C = 0.159/f*R, where C is the capacitance, f is the line frequency, and R is the measured resistance of the pot. A capacitance meter is much easier, especially for smaller value caps. Every multimeter will measure resistance.
Tolerance isn't really measured because it is a range. It is the amount that the component will vary from the specified value, ie a 5% tolerance 100 ohm resistor should measure between 95 ohms and 105 ohms.

[sofaspud]

Another thread here took me to Conrad's page for a capacitance bridge. This is an expansion of my procedure above, and provides for a wider range and more accurate measurement.

[Ron E]

Originally Posted by sofaspud

Adjust the pot until the voltage drops across the R and C are equal. Disconnect and measure the resistance of the pot. Then C = 0.159/f*R, where C is the capacitance, f is the frequency, and R is the measured resistance of the pot. A capacitance meter is much easier, especially for smaller value caps. Every multimeter will measure resistance.

You can also do this much simpler with a soundcard, a dead pair of headphones (for the cord, plug it into your PC speaker out), a fixed resistor (8-10 ohms) and a multimeter.

hook the resistor and capacitor in series on one channel and do as sofaspud recommends. Vary frequency using a tone generator program until the voltage drop is the same and calculate C.

Tolerance in percent is simply 100 x (M-V)/V
M=measured value
V=specified value