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What is a diode?

from Wikipedia

photo by John Maushammer

In electronics, a diode is a two-terminal electronic component with asymmetric conductance; it has low (ideally zero) resistance to current in one direction, and high (ideally infinite) resistance in the other. A semiconductor diode, the most common type today, is a crystalline piece of semiconductor material with a p–n junction connected to two electrical terminals.

A vacuum tube diode has two electrodes, a plate (anode) and a heated cathode. Semiconductor diodes were the first semiconductor electronic devices. The discovery of crystals' rectifying abilities was made by German physicist Ferdinand Braun in 1874. The first semiconductor diodes, called cat's whisker diodes, developed around 1906, were made of mineral crystals such as galena. Today, most diodes are made of silicon, but other semiconductors such as selenium or germanium are sometimes used.

What are diodes used for?

Diodes have many applications in the world of electronics.  Here's some of the most common:

  • Radio demodulation
  • Power conversion
  • Over-voltage protection
  • Logic gates
  • Waveform clipping
  • Temperature measurements
  • and more!
This guide was first published on Dec 19, 2014. It was last updated on Dec 19, 2014. This page (Learn More) was last updated on Nov 11, 2019.