Thyristor and Zener ???

Thread Starter


Joined Dec 23, 2009
Wats up boiz?

So i i just saw a few of these and i still dont know what they do?

What is a thyristor and what does it do? (what are they used for)

Whats is a zener diode and what does it do? (what are they used for)


Joined Oct 9, 2011
Well Pulse, let me give this a crack.

Your first question about a thyristor, also known as a VCR (Voltage Controled Rectivier) is coverd very concisely in Basically it is a gated diode that only conducts when it is forward biased, AND the gate is triggered VIA a positive voltage with respect to the cathode. In its coducting state, a thyristor will latch 'on', regardless of the gate voltage, until the forward voltage across the cathode and anode is removed.

A Zener diode is a bit more complex. Again, it is covered very accurately in It is a diode that is actually designed to conduct in reverse polarity at a specific voltage level. To explain why it is unique from a regular diode, here is what happens to a regular diode that is reverse biased at a higher voltage than its rated maximum. In such a state the weakest part of the P/N diode junction will break down, and from that point, the effect spreads to the rest of the junction as more and more current flows in the reverse direction. This is called the Avalanch Effect. A Zener diode, also known as an Avalanch Diode, is specially doped so that it acheives a MUCH more stable P/N junction, which, when it is reverse biased to the piont of Avalanch, prevents the junction from breaking down as a normal diode would. Instead, the reverse biased junction maintains a very specific and consistent voltage across its cathode and anode, independent of how much current is flowing, as long as its maximum current rating is not exceeded. Zener diodes are designed to avalanch at different voltages, (Ex: 3 volt, 4.5 volt, 15 volt, 50 volt, etc...). Zener diodes are typically used as voltage regulators in low power circuits due to the nature of its reverse bias state maintaining a stable voltage, as well as voltage references for higher power regulators, switches, etc.

I hope this helps.
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