constant current and voltage circuit wanted for laser (please)

[large_ghostman]

hi
can someone please point me to a constant current and voltage (7v i think) for a red 5mw laser, i have looked around but ended up confused its for part of my robot project thank you
LG

 

[throbscottle]

If it's a laser diode you're talking about, this looks usefulhttp://talkingelectronics.com/pay/BEC-3/Page53.html.
You'll need to study the specifications for the exact laser diode you want to use in order to modify the basic circuit to your needs.
If you're talking about using some other kind of laser, such as helium-neon, you will need a high voltage supply (several kilovolts) with lots of ballast resistors in series with the output (sorry I don't know details).
HTH.

 

[large_ghostman]

its a laser diode like a pointer it was from ebay so no datasheet and all i know is its red and marked as 5mW i am not sure what the current should be for it
thank you logan

 

[cowboybob]

its a laser diode like a pointer it was from ebay so no datasheet and all i know is its red and marked as 5mW i am not sure what the current should be for it
thank you logan

If it's the one I'm thinking of (from a sonic dog repel gun w/ a laser pointer), it draws ≈20ma at 3 VDC for max (best) excitation.

Should point out that it's easy to burn out with excess V.

With whatever power source you're using, start out with a HIGH value series resistor (10k or better) and work your way down until you get get a decent lase output.

 

[large_ghostman]

i got some info wrong i found the laser on ebay its this one **broken link removed** apparently its 3-4.5v and has 2 wires

 

[ericgibbs]

i got some info wrong i found the laser on ebay its this one **broken link removed** apparently its 3-4.5v and has 2 wires

hi L,
As your Bot has a 3.3V psu, I would use that.

 

[large_ghostman]

yep i will use 3.3v i think its 20ma for the laser but trying to find out to make sure then i can look for a suitable circuit thats easy to follow i cant open the other link that was posted it looks like that site is blocked on this computer (dads laptop) no ideA WHY

 

[throbscottle]

If there's no part number on that little module, I'm wondering if you can unscrew the end to take a peek at the laser diode inside - it may have a part number on it. If you do this, be very, very careful and take static precautions, don't force anything, don't pry with a screwdriver, etc. If you can find a part number, google it for a datasheet.

 

[large_ghostman]

ok thanks i will do that