Diodes 101

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Updated: 2005-03-28 by HoloM (the god)
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Colin Kaminski

Diodes 101

Post by Colin Kaminski »

Diodes 101- I don't know a great deal about electronics but here is some information from The Art of Electronics by Horowitz and Hill

1. A diode is a semiconductor made from a P/N junction.

2. There many kinds of diodes. Laser diodes, Photo diodes, Zener diodes and more.

3. A diode has an Anode and a Cathode. The Anode is shown in a schematic by a the base of an arrow. The Cathode is a flat line. Below the breakdown voltage current can only flow one way, from the anode to the cathode. (In the direction the arrow points.)

+ Anode --->|--- Cathode -

4. When current passes through a diode there is a voltage drop of .5 to .8 volts.

5. Normally diodes are used with current flowing from the Anode to the Cathode. So for a laser diode hook the + to the anode and the - to the Cathode.

6. Photo diodes are usually "reversed biased". This means they are hooked up backwards. Photodiodes are fast (response times of 1ns) but there is a trade off between speed and noise. Photodiodes are not very good with very low light levels.

Thilo,

I hope this answers some of your questions.

Colin
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