A.1. Capacitor

Capacitors store an electrical charge for a short time and are used in digital circuits to filter (smooth out) dips and spikes in electrical signals. The most commonly used capacitor is the nonpolarized ceramic capacitor; for example, a 100 nF disc capacitor used for decoupling (reducing noise spikes). Electrolytic capacitors can generally store more charge than ceramic caps and are used for higher current circuits, such as power supplies and motor circuits. Electrolytic capacitors are usually polarized, and the negative leg (marked with a minus sign) must be connected to ground (or to a point with lower voltage than the positive leg). Chapter 8 contains examples showing how capacitors are used in motor circuits.