RC-Monster Forums - View Single Post - DIY High Power LED Rechargeable Flashlight

Finnster · 02.21.2010, 01:09 PM

I have not played with the large leds, but whenever I built little led circuts, for rcs or flashlights, I simply used a resistor to limit battery current. Leds cause a voltage drop across them ( being diodes.) I simply calc'd the batt voltage minus the drop voltage (3-4v iirc for little white leds) then choose a resistor that would provide 20ma at that voltage. More stable the output voltage, more consistent the brightness. Best results were running off a ubec.

Idk so much about the big led. You have to calc the needed wattage of resistor as well. You may just need a small one to run that right off the batt, however I'd have to see more specs and sit down and work it out.

For all the hassle Id prolly just buy the proper driver for such a large and pricely led. I also tested mine on a breadboard first to test my thinking and design.

	(#7)
Finnster KillaHurtz Offline Posts: 2,958 Join Date: Apr 2006 Location: Bucks Co, PA	02.21.2010, 01:09 PM I have not played with the large leds, but whenever I built little led circuts, for rcs or flashlights, I simply used a resistor to limit battery current. Leds cause a voltage drop across them ( being diodes.) I simply calc'd the batt voltage minus the drop voltage (3-4v iirc for little white leds) then choose a resistor that would provide 20ma at that voltage. More stable the output voltage, more consistent the brightness. Best results were running off a ubec. Idk so much about the big led. You have to calc the needed wattage of resistor as well. You may just need a small one to run that right off the batt, however I'd have to see more specs and sit down and work it out. For all the hassle Id prolly just buy the proper driver for such a large and pricely led. I also tested mine on a breadboard first to test my thinking and design.