A problem with driving 808nm diode

[hyparh]

Hi to all
I’ve bought a 500mW (650mA) 808nm laser diode and a driver with LM317 that I thought will be fine with it. The first attempt was with a 7.4V Li-ion battery, I slowly decreased the pot’s resistance and watched carefully the diode but it wouldn’t shine. Then I tried to put more power (around 15V) to the driver using a big transformer with fairly enough amperage potential. Again very slowly lowered the resistance and again nothing… the diode has a housing and radiator, it stays stone-cold whole the time and no light has been emitted, I even tried focusing with lens.
Is the problem in the driver and if so what corrections I can do to make it works?

Here is the schematic of the driver:



Thanks in advance!

 

[Ghostchrome]

First of all, that driver is crazy complicated, and it doesn't need to be. All you need is an LM317 and a resistor (and maybe a pot if you like). Set it up in constant current mode and you're good to go.

Second, it could be that the diode is bad, or that you fried it by accident. There are a 4 capacitors on that driver, if you didn't discharge them before you hooked up your diode it's probably dead.

Third, 808nm is infrared and will be invisible to the eye. You might be able to see a dim purple dot. DON'T look into it!

It could be lots of things. Post some pictures of your setup and we might be able to help you more.

 

[Sigurthr]

Also, that driver is NOT set up for CONSTANT CURRENT.

That there may be your problem as there is no way to control the current going to the laser in that schematic.

 

[hyparh]

Thanks guys, I'll try to fix it as soon as this cold moves away, I can't work in the garage at these temperatures. Here in Bulgaria is a hell of a winter... ::frozen::