Accepted Answer

Bamaboy; Diodes conduct current only in one direction. When forward biased, a ( silicon ) diode will conduct practically no current until the voltage across it reaches about 0.7 Volts. A zener diode is used in the reverse bias mode and will conduct no current until the applied voltage reaches the rated zener voltage which can be anything from a couple volts up to hundreds.

Using a series resistor, a zener diode becomes a common voltage regulator, holding the zener voltage across a wide range of currents. Transistors can be used in conjunction with zener diodes to regulate much larger currents due to the greater power dissipation available with a transistor heat sink.

If that's enough, please click Accept, or feel free to ask for rectification or amplification. As always, positive feedback is appreciated.   Jeff

Expert:	Jeff
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Answered:	1/13/2009

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BSEE 30+ years electronics, computers, radio & TV engineering & repair