Driver for multiple IR laser diodes

[Yun]

Hello, it's my first post

I'm building a noctovisor device using CCTV cam and scope from old analog cam. I'm considering using IR laser diodes for lighting objects to be visible in nactovisor, because i got LOT of these diodes, taken out from CD/DVD burners. And the range would be longer than LEDs.

I'm looking for schematics for one, possibly efficient driver to power these LDs. Could somebody help me make this? I'm not very good at electronics, but i made a few drivers based on LM317 for red LDs from DVD burners.

Driver should be powered by 12 volts and be efficient to save the energy, it could also have a pot to control the lighting (dim to save battery when full power is not needed).

Could somebody good with electronics draw me a schematic or give me some clues? I would be grateful.

Sorry my english, its not my native language.

 

[Wolfman29]

So... shameless plug here... but you could stick a bunch of these IR diodes in arrays, such as 6 in parallel in series with another 6 in parallel... then you could use a BlitzBuck

Those are about 90% efficient, can take up to 25Vin, and have a small pot to adjust between anywhere from 1.2A and 3.1A.

Not just trying to sell you something (well, I am...) but I actually think a buck driver would be the best solution here.

Anyway, just check out my signature.

 

[Yun]

Thanks for the reply

I would buy it, believe me, but if you don't have branch in central europe than i'm afraid i would spend more for shipping than driver itself Or maybe you know the way for cheap shipment?

However, is 6 a good count to get good current and voltage for these diodes directly from 12v? How much current they need? Maybe you could point me some thread about these, i cant find it. Sorry for being newb, i guess i'm using search wrong way :]

 

[Wolfman29]

Righto!

The reason I said 6 is because, assuming these are single-mode IR diodes, I wouldn't go any higher than 200mA per diode unless you know what the maximum is.

 

[Yun]

I connected 6 diodes in parallel, it works, however i have to make 6 separate radiators because making one would short circuit, they are pretty hot after 15 secs of using. Big thanks for advice, noctovisor is nearly finished, only case left for me to do.

 

[Wolfman29]

Making one radiator shouldn't make it short circuit? That would be in series where that would happen.

 

[AUS]

I wouldnt advise connecting them in parallel.
Laser diodes need constant current. If they are in series the current is tha same through all of them, you just need more voltage (you add the voltage drops together). If the are in parallel the diode with the lowest voltage drop will get more current and the one with the least voltage drop will get very little current.

 

[Wolfman29]

Come to think of it, AUS is correct. No idea why I advised parallel? >.>

 

[Yun]

i connected them serial anyway ;]
they are still working, but hot as hell so i cant use them too long until i figure some cooling
im gonna put 6 small copper radiators, one for each LD

thanks all