How To Protect A LED From Reverse Polarity

Thread Starter

haberdasherylondon

Joined Mar 11, 2009
1
Hello.
I'm using a 9V battery source to power 2 LED's each with a 3.5V forward Voltage. I need to protect the system from reverse polarity that might harm the LED's. I imagine that I should use a zener diode to do this, but I don't know how to specify the right diode.

Can someone help me?

Thanks
-Dan
 

bertus

Joined Apr 5, 2008
22,266
Hello,

A diode in series with the leds will help.
A standard led will hold at a reverse voltage of about 6 Volts.

Greetings,
Bertus
 

Wendy

Joined Mar 24, 2008
23,408
Or you can put a conventional diode back biased compared to the LEDs. If you do reverse bias them the conventional diode will soak up the current and drop 0.7V, which most LEDs can handle OK.
 
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