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[More Coffee]

I have a 4.8 v reciver pack..about 800mah//Or I could use a pacK that carries 4 AA batteries each cell rated at 2600mah


I was wanting to use a universal PCB to mount some simple circut or IC that would give me an output of 3-3.5 V ..so I could just solder the wires from the leds to it ..mount and be done..just plug in the battery ..vs trying to make another harness and have a pile of rersistors to use with 7.2 volt
My leds are rated at 3.1-3.8 v..

With a small IC or something I could just run them direct and do away with the resistors ...right?

[knoby]

You could use a LM317 regulator, have a look at the link & it shows a simple circuit

 http://www.electronics-lab.com/articles/LM317/

R2 resistor needs to be around 370 ohms.
cheers Glenn

[More Coffee]

Thanks ...Im looking into it ..believe have the lil'bits i need

[malcolmfrary]

LEDs will still need current limiting, they will still try to regulate the output voltage from whatever is supplying them down to their forward voltage at whatever current the supply can give.  If this is less than that required to destroy the LED, it survives, if more, it doesn't.  Those LED torches and keyrings do rely on the internal resistance of the battery keeping things in check.  And, of course, there are some LEDs with built-in resistors (and occasionally active current limiting circuits) to allow them to be used on a range of voltages without wiring extra resistors in series.

[More Coffee]

Geez ... no easy way around this ..