Zener Diode Calculator

It will calculate the series resistor for a zener diode so that:

• You can get fixed voltage at output (same as Zener voltage).
• You do not burn your zener diode.
• You feed only the current needed to your load.

Formula used is

Where:

Rs = (Vin - Vz) / Iload

• Rs = series resistor (Ohms)
• Vin = input DC voltage (volts)
• Vz = zener diode voltage (volts)
• Iload = load current in Amps (you can also use mA)

Explanation (how it works):

So friends, here we first ask for 3 things:

• Input voltage (like from battery or DC source).
• Zener voltage (fixed output voltage you want).
• Load current (how much current your device will pull).

Then using formula we calculate how much resistor we need to drop excess voltage and save the zener diode.

This resistor drops the extra volts and lets only safe current go into the zener and the load.

Also shows how much watts your zener will eat, so you do not use weak zener which can burn.