Author Options:

If it is not shown, how do I know which lead is positive on a capacitor? Answered

I don't know which is the positive and negative lead on a capacitor. I want to know how to know which lead is positive or negative.


if it is a can type, 2 wires comeing out of the bottom then the wire closest to the edge is negitive. the center one is positive

You have a 50 / 50 chance.

If it doesn't explode you got it right.

Seriously though - there are two main types that are polarised. Electrolytic and Tantalum. The electrolytics have a stripe of minusses down the side near to the negative lead or - as mentioned below - a groove around the end near the positive side. The can or case of the electrolytic is usually the negative.
If you have the tantalum type and it hasn't been mounted yet then the longer lead is the positive or if there is any writing on the side of the tant then (in all of mine that I have just checked) the positive lead is on the right when this marking is facing you.


9 years ago

As AndyGadget has mentioned a pic would be useful. You need to identify its composition as capacitors are formed from various material types... . ceramic, poly, paper etc. Most of these are generally none_polarized. Electrolytics can be both but usually have some identification markings as already mentioned.

What value is it? - If it's under 1 micro farad (uF) then it's likely to be non-polarised, i.e. you can put it in either way around. Also the case if the case appears to be all plastic.
If you can see any metal it's likely to be a polarised capacitor. I've seen polarised capacitors with no markings - these have an indented ring around the positive end.
There are non-polarised electrolytic capacitors (usually found in loudspeaker crossovers) but they would normally be marked '+' at both ends.
Any chance of a picture?

Any polarized capacitor has a - marking the negative side.If yours does not have one,then it is a non-polarized capacitor.