I was testing a couple of low-cost laser diodes that come from china and I was wondering why those diodes don’t have any protection/driver circuitry. Those diodes come with a simple series resistor for current control which is not a good idea nor stable. Laser diodes are harmful and should have some sort of constant current circuit as a basic protection for the laser diode. As result, I built this circuit which provides highly accurate current control. The module is a great tool to drive low-cost laser diodes with superb accuracy. This circuit can drive diode starting from 0 mA to 115mA, usually, these cheap diodes require around 30mA current. The project has an onboard multi-turn potentiometer to adjust the output current with great accuracy. It is advisable to turn the trim-pot to zero level and then hook-up the laser diode.