Need help to build a laser diode power supply.

I'm gonna venture and say that since you have the setup, and if you just want a quick fix-it, you can put a variable resistance in parallel with the diode. When you lower the resistance, you lower the current tot he diode, and vice-versa. As for using the LM317, I am trying to get one myself, and have been waiting on the chip itself to get in to the local electronics store. So far, the best source I have found are the chipmaker's website itself lists a few power supplies using the LM317 in such an application, and then there is the amazing Sam's Laser FAQ. Both will give you full schematics and great help.

--DDL

Thanks for replying Daedal.

Are you sure a variable resistor in parallel would work? Wouldn't it burn the variable resistor when the resistance is set to low level? At the moment I'm using a 1R 10% 25W wire wound resistor (this thing is HUGE :naughty in series with the diode. I tried a .25W and 1W variable resistor in series and smokes came out straight away. Lucky it was not from the diode, but from the variable resistor instead. I don't think a variable resistor can be a quick fix to my problem as this diode chew 2.5A, which means I would need a 10W+ variable resistor to be on the safe side.

Anyway, which chip manufacturer website did you look into? Got any links?

Can wait to properly feed this diode. It burns stuff like crazy. I wish it's producing 473nm cyan beam but too bad it's actually producing 808nm deep red instead.

Cheers.

Well... let me fetch some links for you... but hey, I know you probably read this a million times elsewhere but here goes again... Watch your eyes... invest on some good safety goggles, they are definitely worth it...

NS: http://www.national.com/pf/LM/LM317.html#Application Notes
Sam's FAQ: http://www.repairfaq.org/sam/laserdps.htm#dpstoc

Hope these help you a bit. I just grabbed them really quick. I'm sure someone will provide some further insight as to a better application, but this should be some good reading material till then

GL;
DDL