A diode is a common electrical device that restricts flow of an electrical current. It can be simply thought of as a check valve for an electrical circuit. Any circuit that requires flow in a particular direction will contain diodes. There are several different uses for diodes in the different electrical devices listed below. Power Conversion- Rectifiers are power converters constructed from diodes. Diodes are used to convert alternating current (AC) power to direct current (DC) power. In voltage multipliers, diodes are used to produce the reverse reaction, converting DC electricity into AC. Over Voltage Protection - Diodes are commonly used in circuits and other electronic devices to prevent high voltages from damaging sensitive material. Integrated circuits that are used in computers use diodes to prevent external voltages from damaging sensitive transistors. Diodes are also used in relay circuits and other devices to de-energize components rapidly to avoid the voltage spikes that would otherwise occur. Temperature Measuring- In some cases, diodes can be used as temperature measuring devices. When temperature drops, the voltage passing through the diode changes, thus triggering a reaction. Radio Demodulation- Radio demodulation was the first practical use for the diode. Diodes are used for amplitude modulated (AM) radio broadcast demodulation. A radio signal consists of alternating positive and negative peaks of voltage, and the diode rectifies the signal to that of the desired audio signal. The signal is then gathered and fed into a transducer which produces sound.