Led Driver Board

This is a lamp made with four ultra-white LEDs and has a regulated light output from 10Vdc to around 20Vdc @ 40ma The regulator LM317L and resistor act as a current regulator which is set to 40ma. Current flows from thesupply through one pair of LEDs, through the regulator, through the other pair of LEDs, and back to the battery. The capacitor filters out noise on the power supply lines. The LED pairs must be matched so that the current through them is roughly equal. see Autocad 2007. zip for circuit details