I want to make a protection circuit for my LCD i use for prototyping. It requires +5V and i use a powersupply to power it and i'm afraid one day i might have the voltage up to maybe +6V and i'll fry my LCD.

I'm considering using a 7805 but i didn't want to have to have a Vin of ~7 Volts i wanted to be able to have 5V but if i go above 5V have a circuit that limits the voltage.

I was looking back through my textbook and looking at a limiter circuit using a diode in parallel with the load will limit the voltage to .7V so i was thinking if i used 7 diodes in series .7 * 7 = 4.9V i could make a limiting circuit that way...

But it seemed sloppy and wondered what other people's idea's were.

Thanks,
Blake

 

Since existiert a device, - called zener diode - no need seven diodes for this purpose. Apply an 5.1V zener with serial 10ohm resistor for protection.

Attached Images

prot.GIF (1.3 KB, 86 views)