Laser Diodes?

 So, I have 2 laser diodes, but I don't know what the voltage/amperage/wattage on them is. Anybody know how I could figure this out?

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legionlabs7 years ago
I would use a power supply of low current, and controllable voltage (such as a simple potentiometer and a 9v battery).

Do not look at the laser. In fact, seal it in a box with a photodiode, solar panel, or even an LED (which can act as a photodiode) and measure the voltage across it. Start at low voltage, and slowly increase until you get a voltage across your detector. When you do, use a multimeter to measure how much voltage you applied. This is your laser diodes forward voltage. If nothing happens, it's burnt out, connected backwards, or both.

Now, if you like opamps you can build a power supply of this set voltage and control current. When you burn out one diode, you can guess what the limit is on the next... or you can measure heat buildup and guess. Forward voltage drop times current should give you approximate dissipated power.

If you don't like opamps, you can use a power supply of set voltage and control duty cycle using two 555 timers... the first in astable and the second in stable mode. If you don't have any 555 timers on hand, you can use hex inverters if you're clever.

If they are small chances are they are 1mw, 5mw, 300mw, 500mw or 1w. Observe proper laser safety and good luck!
Hinesdarrel3 years ago

To know the voltage of your laser diodes, you can use an Ohm-meter or
multimeter to measure the internal resistance, then you use Ohms law to
calculate the amps. If you are looking to buy laser diodes and know more information about it, then you can visit

toelle7 years ago
If you know the voltage of them, then you can use an Ohm-meter or multimeter to measure the internal resistance, then you use Ohms law to calculate the amps.
CharMio7 years ago
 3 volts is a standard voltage for lasers, don't worry about the amps
Re-design7 years ago
If you don't have the number off them then it's kinda hard to figure out.  What voltage was supplied before you took them out of what ever you took them out of?

You could hook them up to a variable voltage power supply, start out very low and slowly increase the voltage until they light up, then stop.

Caution should be used since some laser diodes are not visible.
iBurn (author)  Re-design7 years ago
I do have the numbers off of them, but alas google yielded nothing helpful...