LM317T Voltage Regulator with Pass Transistor

Link to page: www.pcbheaven.com This is the remake of the third episode of the LED driving and controlling methods Theory Series. In this episode i explain how can someone design a constant current LED driver with a single transistor, biased with a Zener diode to achieve constant current regulation regardless of the power supply voltage. Additionally, i analyze a second circuit with sme functionality but instead of the Zener diode i use two simple diodes. On-line calculator for this circuit: www.pcbheaven.com



http://www.youtube.com/watch?v=fMc99rM6u4k&hl=en