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^{Identify your capacitors polarity}!

What is polarity? An electrical condition determining the direction in which current tends to flow. Hence, negative (-), positive (+).

What does "almost always" mean? There are always exceptions. You may find one marked differently, who knows!!

Lets start with both, Radial (wires coming out the bottom), and Axial (wires coming out the sides)

In the example above you will notice five different ways to show polarity. There are more, but I think this will be enough to get the point. The arrows and stripes are "almost always" present. You will find many variations of this as well. They always depict the negative lead. The fifth way to find the negative is the shorter lead. 

In this example above you will find an added way to figure out the polarity. Remember these are marked with arrows and strips just like the radial caps at the top. Almost always pointing to the negative end. On axial caps though, we can find the polarity just by looking for the aluminum housing. The aluminum housing is almost always the negative end. The other end will have a rubber seal, sometimes epoxy or glass, but always insulated from the housing. If you see no marks, or both sides are insulated, then you may have a non-polarised electrolytic capacitor. You would find these in crossover networks, speakers, and some amplifier circuit boards. Other than that, this should help for 99% of them.

NOW, a couple things about capacitors with out a polarity!

Take a look at these. The first one has no markings at all. This is a normal axial capacitor. This is the most common type found in early radios, and televisions. As well as most early electronic devices. They used paper and oil as a dielectric. The new capacitors use a metalized poly film. Called a dry capacitor. The new one will never dry out on you, will last your lifetime PLUS, and will perform just as good if not better than the original.

The next capacitor is basically the same except they do have a mark for a polarity. Not necessarily for Positive and Negative. This mark denotes which side is connected to the outside foil. The mark will be a stripe running all around the body of the capacitor. The reasons for the marking has to do with coupling in Hi Fi amps. If you use these correctly they will cut down noise generated internally in the amp. You would want to connect the marked end in a special way so the out side foil doesn't interfere with another component. Or can help eliminate interference from other components.

Most people call these audio caps, because they are primarily used in critical, or high end amplifier circuits.

Well that's it. I want to keep it simple and informative. I hope you found it to be both. Now you can use this guide to insure you install your caps correctly. Keep in mind this coves only some capacitors. Since I specialize in antique radios I stuck with the most common types.

The information contained within this website "www.wjoe.com" is derived from theoretical information based on experience and knowledge obtained over my lifetime. The reader "you", are ultimately responsible for any and all information used from this site. Any damage, or any consequences you experience from this information is solely your responsibility. This information is a free service, so please enjoy it! Any other use, retention, dissemination, editing, selling, or copying anything from this site, for any intent is strictly prohibited. Unless you obtain written permission by me at joe@wjoe.com. Any information on this web site is owned by myself and is intended to aid you in your research about Antique Radio. Please enjoy!!!!!!

PLEASE feel free to email me with additional questions about this article.

07/17/08