I would like to know how many of these leds could be put in series because of the amount of ma. they draw. They are 3 watt leds and draw 700ma voltage is 3.5to 4 vdc . I want to run atleast 2 in series,I found a cir,useing LM337 regulator,they go up to 1.5amp.Or dose any one have a cir.for running about 2 or 3 ...3watt led in together from either a 6 or 12 volt battary.Running 1 is pretty easy. Im wondering how they do it for car bulbs and run from 12 to 14 vdc.They have Dome lights Tail lights ,and they are very small.Im many they use 1 watt leds and also just the ultra bright leds.
I would like a cir, for this so that I can put one or a few together.
Thanks
John

 

John, the easy way to get decent efficiency with the higher power LEDs is to use a BuckPuck:
http://www.ledsupply.com/buckpuck.php
The above page is just for reference.

If you have some electronics skills, you can build your own switching regulator(s) using ICs and a few components. Research regulators such as LM3401, LM3405, LM3407; there are many others.

LM317/LM337 regulators are linear; they will not be efficient, and will dissipate power as heat.

 

Greetings! And welcome to AAC!

I've moved your post into its own thread, where it will draw more responses:
This is the origenal thread: http://forum.allaboutcircuits.com/showthread.php?t=12775

Please refrain from "hijacking" existing threads with tangent or off-topic questions. You can create new threads for new questions using the "New Thread" button on the upper left of the page.

Greetings,
Bertus