Zener diode- over voltage protection

299

07:22:13

Power is cut off from the load side if the voltage exceeds that set by the zener diode.
Ex.  5V circuit with LED load.  Power cut off around 8.82V as LED approaches 20mA.

published 6 years ago

digital_electronics

6 years ago

Another useful circuit, thank you for sharing...👍

PrathikP

6 years ago

Nice circuit

fatcat2

6 years ago

What is happening is that one transistor "stops" the other when it is forward biased. I like it.

2ctiby

6 years ago

It's nice as long as the source voltage does not go up past about 600v

giomix

6 years ago

Only in simulator.

2ctiby

6 years ago

@giomix ... A voltage source of 600v would not fair well for the then supplied current at the base of the central bjt etc in reality, not just in the simulator.... and if that central bjt burns out (open circuit), then the load LED gets overloaded too. This is likely to happen before 600v is reached in reality, but we can only visually see the LED overload here on EC after 600v, since EC does not show overload/burning of many other components. I agree with you that a simulator is likely to be restricted in presenting a real 'heavy' overload situation. It's a nice presentation here for slight battery-like overloads.

fatcat2

6 years ago

But typical power transistors have a breakdown voltage lower than 600V, right?

2ctiby

6 years ago

Like I said .."This is likely to happen before 600v is reached in reality, "

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