Power a 3V laser from from 5VDC

[tubesornothing]

Got a little 3V laser I wanna hook up, but all I got is 5VDC regulated.  Do I have to use a regulator or can I just calc the current and use a resistor?  The laser supposedly has some kind of automatic power control - thats probably output power though...


If I was going to use a resistor, I need a 2V drop.  The laser takes 20mA.  R = V/I = 2/.02 = 100R   - sound about right?


thanks
ToN

[PRR]

Where did you find a "3V laser"?

Do you have a link?

[tubesornothing]

Sure, no data sheet, but this is it: 


http://www.apinex.com/ret2/lmcan.html

[PRR]

Nobody has a clear data-sheet for this general class of lasers (brass tube, 2-wire, under $50).

Some of the higher-price modules specify "5V +/-1%", an incredibly tight spec. Especially since we know the cheaper ones are sometimes powered with two batteries.

I just can't help. For $2, I'd guess, but for $35, I don't want to risk it.

[tubesornothing]

Good enough for me - thanks.  I will use a regulator.