Laser Driver Circuit

Homemade Laser Driver with LM317

This is a simple and cheap homemade laser driver.

The LM317 is capable of up to 1.5A,

which makes it possible to use it for >1000mW laser diodes.

Build your own homemade laser driver

Used Parts

·         LM317 Voltage Regulator (rs-components)

·         1N4001 Diode (Reverse Voltage Protection)

·         10µF Capacitor

·         Resistors (Value depending on diode current)

·         Potentiometer (only necessary if you want to change the diode current)

·         Switch

·         Fuse

All parts together cost me around 2€. (~2.5$)

Calculate Resistors

The Resistor is to be calculated as follows:

Resistance = 1.25V / max. Current to Diode

The 1.25V is the Reference Voltage of the LM317.

Example:

maximum diode current is 250mA:

1.25V/0.25A = 5Ohm

The Variable Resistor can be used to control the current to the diode.

The Current can be calculated with this formula:

I = 1.25V / Resistor + Variable Resistor

Insert the momentary Resistance of the potentiometer here.

Curcuit