Homemade laser driver

Used Parts

• LM317 Voltage Regulator
• 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.