how much voltage to connect a 1watt LED with LM317 driver circuit
(i mean 6v r 9v or 12v)

thank you

 

Whichever you want.

You will want to use the lm317 as a constant CURRENT regulator.

Set it for 350ma for max brightness from the 1watt LED.

 

What is the color? How much voltage a LED drops is very dependent on color, even though it remains a current controlled device.

LEDs, 555s, Flashers, and Light Chasers

 

thank you sirs


i bought a 1 watt led (warm white) and i use LM317 as a constant CURRENT regulator, the confusion is how much supply giving to the circuit to maximum brightness and LED long life.

thank you sir

 

You will find that info on the 317 datasheet.

The voltage doesn't matter per-se.

You need enough voltage to turn on the led around 3.5v and enough voltage for the regulator.

9v should be plenty.

http://www.national.com/ds/LM/LM117.pdf

 

Umer Farooq I presume

 

If you aren't experienced in electronics, there are "Buck Pucks" that have everything you need to run an LED from a higher voltage supply at 350mA.

They are switching regulators, and the LED circuit overall would use a lot less power than with the LM317 linear regulator, which would get warm/hot depending on input voltage.

What is the application of this? Will there be more than one LED? Is it for a flashlight, room light, strobe, etc? There may be even better options than these.