Diode Description
fig.1 - Diodes
Diode, electronic device that allows the passage of current in only one direction. How things evolved … The first such devices were vacuum-tube diodes, consisting of an evacuated glass or steel envelope containing two electrodes - a cathode and an anode. Because electrons can flow in only one direction, from cathode to anode, the vacuum-tube diode could be used as a rectifier . The diodes most commonly used in electronic circuits today are semiconductor diodes. The simplest of these, the germanium point-contact diode, dates from the early days of radio, when the received radio signal was detected by means of a germanium crystal and a fine, pointed wire that rested on it. In modern germanium (or silicon) point-contact diodes, the wire and a tiny crystal plate are mounted inside a small glass tube and connected to two wires that are fused into the ends of the tube.