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.

LM317 homemade laser driver

Build your own homemade laser driver

 

homemeade laser driver curcuit

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 = 5 Ohm

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.

 

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