Hey =)

I’ve got a 5mw 980nm laser needing 3v at 50 mA.
I have an dc power adaptor which provides 3V at 300mA.

Do i need to do something before wiring things up ?

I don’t think you need to change anything, it is the voltage that matters, the current of the power adaptor is 6 times that required by the laser, so you could have 1 to 6 lasers wired to the one adaptor without loosing power.

However despite being 90% sure, I would wait for a second opinion before you do anything

I was thinking the same thing, it was just to be sure. You’re the second opinion :D
Thanks.

High mA can destroy your diode.  Might not straight away but it won’t last as long as it should.  The laser will be connected to a driver board so in theory it should be safe.  Depends what the board is built for.  It would be better to supply what it needs.

Medd

Is it really okay to simply wire the laser directly to a dc or ac adapter? I talked to a guy at an electronics store today (he could be totally wrong, I don’t know how well he knows his stuff) who told me that that’d destroy your diode pretty quick.

If it’s similar to the modules I have from aixiz, a little cylinder, then it has a driver board inside it.  You can link it up to 2 AA batt’s and it will run just fine.  It would be better run it off a regulated power supply though.

Plus the main problem you will have at running it at higher mA is it will up the mW it’s putting out.  A dangerous thing when dealing with IR!

Medd

Hi Meddigo,

Thanks for the quick reply. I’m not very experienced when it comes to this stuff so bear with me.

The lasers I got are 10mW 780nM lasers from aixiz, actually. So it should be safe to power them off a 220v to 3v power adapter, except for the fact that I’ll have to deal with higher mW output?

Thanks!

In fact, i was thinking that dealing with mA was the role of the “integrated laser driver circuit”.

Bah, if we need to supply the correct current + mA. How can we do that ?
Resistor ? less current ?

Your power adapter will provide a constant 3V at whatever current is required(allowed) by the connected components up to 300mA. A laser diode (like all diodes) will act essentially as a wire in it’s forward direction, allowing as much current as is available to pass through, but the laser part of the diode can only handle so much current before it breaks. To solve this problem, the laser diode is attached a driver circuit which limits the ammount of current going through the diode. These driver circuits are designed to take in a specific voltage, and will draw up to the specified current to power the laser diode.

So, if you have a laser module ( diode + driver circuit ) then as long as you have a deacently regulated supply with the proper voltage, and enough amperage you should be just fine. If attaching multiple laser modules to the same source, you will want to wire them in parallel.

I’m not saying they won’t work.  They certainly will.  What I’m saying is if you feed too much power or current into the driver OR diode then it will break eventually!  The chances are you’ll be ok.  But you will burn out the diode then it’s just more expense.  I’d run them off some batt’s for test runs.  Or do some tests with your power supplies.  The only dangers you have are putting out more than 10mW, danger to your eyes obviously.  And that you might feed a little too much to the driver board.  As I say though, chances are that the board should regulate what’s going through to the diode.  I can’t defiantly tell you it will be fine, can’t tell you it won’t be.

Or you could go mad and build your own driver for the diode! haha.

Looking at the modules, I think you will be ok.  Good luck!

Medd

Thanks for the clear explanation guys. I’ll experiment as soon as I get my goggles in.

As long as you maintain the rated voltage, the driver should never draw more than the rated 50mA. But either way, considering Aixiz’s own 3.2V powersupply provided on their site is rated at 500mA, it a fairly safe bet that their laser modules will be able to handle being powered by a 3V, 300mA max supply.

Thanks a lot guys.