Polarity Of Capacitor With Longer Lead

April 16, 2018

Terry sturtevant electronics indentifying capacitor polarity. The positive lead is usually longer but be careful if youre reusing old or 2nd hand capacitors the leads may.

Markings And Codes

Capacitor Characteristics And Capacitor Specifications

1 1 Precautions In Using Aluminum Electrolytic Capacitors

For the uneven size lead tantalum capacitors the positive sign still exists on the capacitor so you can do both checks to make sure which lead is which.

Polarity of capacitor with longer lead. The easiest way to determine polarity in an led is by looking at the lead length. A tantalum capacitor may sometimes have a plus sign indicating the positive end. Another method you can use is to look for a flat spot on the edge of the led.

The longer lead is the anode. The polarity of a tiny yellow surface mount led is tested with a multimeter. If the positive lead touches the anode and negative touches the cathode the led should light up.

The flat spot indicates the cathode side of the lamp. Other types such as many electrolytics must be placed in a particular direction. They can be placed either way in a circuit.

Sometimes you can look to the length of the leads as an indication of polarity. The shorter is the cathode. In a case where a tantalum capacitor has one lead that is longer than the other like aluminum electrolytic capacitors the longer lead is the positive lead as shown below.

In some cases the positive end of the capacitor may be longer than the negative one but you need to be careful with this criteria because many capacitors have their leads trimmed. Capacitor polarity capacitor labeling some capacitors are unpolarized like resistors.