89Views5Replies

Author Options:

I have some 50w HPLEDs I want to power. Any help on circuitry design will be wonderful! Answered

The specs are Vf of 15-18V and 3200ma for one and 10-12Vf with 4000ma for the other.  I want to build it cheaply and maybe use the LM350 (?) and resistors (?). I'm going to use a 350W computer power supply since I got 2 of those lying around already. What resisters would I need to use and such?  Somewhere in a data sheet I found I should use a 120 Ohm for R1 but no clue how R1's rating will effect R2 in combination. I'm a novice at these things so lay it out in dumb mans terms =)

5 Replies

user
steveastrouk (author)2009-10-15

These are BIG beasties. You'll waste an awful lot of heat drivingthem from a standard power supply and resistors - and a PC supplyhasn't really got the rails you need available with enough output. You'dactually be better buying a driver, if you haven't got the electronicsknowledge to build a switch mode constant current drive.

Select as Best AnswerUndo Best Answer

user
orbulon (author)steveastrouk2009-10-16

Couldn't I hook up +12 (red) and +5 (yellow) rails to make 17 volts? there's plenty of amps between the 2 rails to power several...

Select as Best AnswerUndo Best Answer

user
steveastrouk (author)orbulon2009-10-16

Not really safe to do that - the rails are not rated at the same current.

Select as Best AnswerUndo Best Answer

user
orbulon (author)steveastrouk2009-10-17

You mentioned a switch mode constant current drive?  Switch mode... can you elaborate on that?  Are there any instructables supplying information on how to construct one with the ratings specified?

Select as Best AnswerUndo Best Answer