Dropdown Reg. Constant Current LD Driver
Input Voltage 8 - 20V


Pic 1. Schematic

From Left to Right : PCB, 0.1uF Cap.(C2), LM317(U1), R1, 100 Ohm Res.(R2),
100 Ohm Pot.(R3), C1, D1, 47uF Al Cap.(C3), R4

1. Solder all component according to schematic - please be careful for C3 capacitor direction(short leg mean minus).
2. Check all soldered part and pin to pin connection carefully(must secure).
3. Connect ohm meter lead to "a" and "b" point.
4. Adjust multiturn potentiometer(R3) to your need resistor value - I recommand more than 12 ohm (clock wise turn will increase resistance and decrease current).
5. Discharge capacitor C3 - Charged energy can break diode immediately(It can prevent by install R4 risistor).
6. Connect LD to LD connector +/- before power ON, if connect LD after power ON, LD will die immediately.
7. Connect 8 to 20V power source to PWR connector +/-.

ex)
Output Current 104mA(a to b resistance 12 ohm).

I = 1.25/R
where I = Current, R = Resistance,

LD Module Must connect before power ON, if not the voltage will over LD limit(immediately die).
More than 110 mA can kill your diode shortly by heat - Max current limit circuit not included.
For use more current must consider U1 and R3 heat.