DIY Knowledge

Diode

Diodo

Diode

Popular term for the rather commonly found semiconductor diode. Development has led from high-vacuum tubular diodes and metal rectifiers to modern silicon semiconductor diodes. However, their field of application has remained essentially unchanged.

Vacuum diodes originally consisted of the heated cathode and the cold anode and were used then for the rectification of high or low frequency alternating currents. Diodes can be regarded as an electric valve which permits the current to flow only while the potential of the anode is positive. The current can therefore flow only in one direction, it is being rectified. In the early thirties metal rectifiers like copper-suboxide or selenium rectifiers were invented. This could be seen as substantial progress because heating the cathode was no longer required.

In the modern silicon semiconductor diode the PN junction has taken over the role which was formerly filled by the distance between cathode and anode in a high-vacuum diode. Nowadays, many types of diodes are used. Electric power tools mainly use high performance diodes, Zener (avalanche) diodes and LEDs (light emitting diodes).