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Could I use this LED driver to drive a laser diode? Answered

I've been trying to construct a blue laser for my friend using KipKay's instructions, but I don't have a good driver for it. If I add an extra current limiting resistor at the end of it, will this (http://www.dealextreme.com/p/2-7v-6v-3w-cree-circuit-board-for-flashlights-15mm-2-7mm-25518) LED driver provide a good regulated output for my laser? If not what else could I use to regulate the output?


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Jack A Lopez
Jack A Lopez

Best Answer 9 years ago

In Step 6, Kip says to feed this diode no more than 170 mA.

Product page for the DX 3-Watt says it's a 700 mA regulator, presumably a constant current type regulator.

Um, I'm pretty sure driving 700 mA of current, through a laser diode that can only handle 170 mA max, will destroy it.

Also note that the DX driver is not adjustable.  There is no pot you can turn to adjust the current setting, like there is on the driver that Kip recommended and linked to in Step 1 (link3), here:

I'm sorry that that driver from laserdiy costs a lot more than the one from DX, but it just so happens that that's the case.

Perhaps you are wondering if there is some way to hack the cheaper DX driver, and to make it adjustable, and lower its current setting?  I think that might be possible but, I suspect it is a task beyond your present skill level.

Anyway, if you really want to get this thing running, but not necessarily pretty and tightly packed into a tiny butane lighter package, I humbly suggest you look into a more simple constant-current regulator.  Specifically that one made from the LM317 linear regulator, and a single resistor R.  Um here:

For that regulator circuit, the constant current is just 1.25V/R.  Example:
choosing R = 100 ohm gives I = 1.25/100 = 12.5 mA
choosing R = 10 ohm gives I = 1.25/10 = 125 mA

I also recommend actually measuring the current through your laser diode while testing it out, either by putting it in series with an ammeter (or a multimeter in ammeter mode), or in series with a 1 ohm resistor, so that you can read the current by reading the voltage drop across that 1 ohm resistor.


9 years ago

How much current does the diode NEED ?