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how to test a capacitor ?

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Well-Known Member
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Obviously you can use a capacitance checker, but i guess you dont have that?
What test equipment do you now have or can get or borrow?
You can test this several ways, so it depends on what test equipment you can get.


Well-Known Member
Most Helpful Member
I always use metalized plastic film capacitors for coupling and for filters with 5% tolerance and my very accurate Fluke multimeter measures them to have values within 2%. The value of electrolytic capacitors is all over the place.


New Member
You can full a lot of tests with a capacitor with a decent digital multimeter.

1) Capacitance Check- If your multimeter has a capacitance meter, measure the capacitance of the capacitor. It should be near the rated capacitance value of the capacitor.

2) Voltage Check- Charge the capacitor up by supplying it with DC voltage. Then make sure that you read this voltage when you measure the voltage across the terminals.

3) Resistance Check- Do a resistance check with the multimeter set on the ohmmeter setting. If the capacitor reads very little resistance, a few ohms, then it's short and defective. If it reads a very high resistance, severeal megohms, then it's open. A good capacitor will be in between those 2 extremes.

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If you don't have a multimeter with capacitance measurement capability, you can use a big resistor and a switch. You charge the capacitor to a certain voltage E, and with your clock in hand, you open the switch so it can discharge through the big resistor with a time constant RC that is big enough to be able to measure the time at which the capacitor voltage is E/2.

You use the discharge equation to get C.

Of course, that's kind of a Scorched Earth approach, but still .. Better than absolutely nothing.


New Member

Capacitance is an electrical property which is created by applying an electrical charge to two conductive objects with a gap between them.you are refer this site so you can got better ideas.>>en.wikibooks.org/wiki/Practical_Electronics/Capacitors#Capacitance_2

Gayan Soyza

Active Member
You need a dedicated capacitance meter to check the capacitance.Most multimeters have upto a certain range like 0.1uF to 100uF etc...that is not enough.

Its a challenge to measure how much leakage current that it has.
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