Diodes 101
Posted: Fri Jul 12, 2002 1:19 pm
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
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