Welcome to Laser Pointer Forums - discuss green laser pointers, blue laser pointers, and all types of lasers

# Help making a test load for a diode laser

#### Macoleco

##### New member
Hi,

I am working on a current and temperature controller for low power diode lasers (<200 mA), and I need to make a test load to simulate them. I found some information and it seems the general idea is to use a resistor of known value (like 1 Ohm), and some diodes. Then you measure the voltage and calculate the current. My question is, how many diodes and what kind of diodes do I use? All the samples I find use different diodes and different quantities.

Thank you.

#### diachi

##### Well-known member
Hi,

I am working on a current and temperature controller for low power diode lasers (<200 mA), and I need to make a test load to simulate them. I found some information and it seems the general idea is to use a resistor of known value (like 1 Ohm), and some diodes. Then you measure the voltage and calculate the current. My question is, how many diodes and what kind of diodes do I use? All the samples I find use different diodes and different quantities.

Thank you.

Regular silicon rectifier diodes work fine. Number required depends on what the Vf of your laser diodes is and what current you are using. Check the rectifier diode datasheet to find the voltage drop of the diode at your operating current, then figure out how many diodes you need to have a roughly equal voltage drop to your laser diode.

#### paul1598419

##### Well-known member
If you are using a 1 ohm resistor the voltage drop across it will also factor into the number of rectifiers you will use to approximate the Vf of your laser diode.

• Anthony P and diachi

#### Macoleco

##### New member
Regular silicon rectifier diodes work fine. Number required depends on what the Vf of your laser diodes is and what current you are using. Check the rectifier diode datasheet to find the voltage drop of the diode at your operating current, then figure out how many diodes you need to have a roughly equal voltage drop to your laser diode.