I actually got my 5mm lazer diode to work!

[Orion]

I recently picked one up for the novolty of it, but would like to actually get it to light up. It has 3 anodes (?) coming off of it in a triangular fashion. I would like to know what I'd need and what kind of voltage it would need. A paper with it talked about 2.2 - 2.4 volts? I'm even more green when it comes to lazer diodes than LEDs.

Thanks!

 

[carbonsparky]

try doing a search for laser diodes. I did this awhile back and found some neat circuits. They are really touchy current wise. Jameco.com sells a laser driver for $7.95 (part# 161736). Yes it is cheaper to buy a laser pointer, but that never stops a true flasaholic.

 

[The_LED_Museum]

My best recommendation to you is to send it back (if possible) and buy a "laser module" instead.

Bare diodes are incredibly easy to pop. Sometimes they'll destroy themselves if you do nothing more than look at them all wrong.

First, go here: http://misty.com/people/don/laserdon.html

Then, come back here and ask all the questions you want, and I'll *try* to answer them.

 

[Orion]

I guess I should have checked that all out before I bought it. Of course, I only paid $2.50 for it. I got it from whitelightled.com where I also picked up 10 Nichia white LEDs.

 

[Orion]

Thanks carbonsparky! I may have to go to that sight.

 

[luxO]

They're not all anodes...it wouldn't work if they were.

There is usually the laser diode anode connection, the anode connection for a photodiode, and a common cathode connection.
The photodiode is very important and should be incorporated into a current feedback circuit to regulate the current through the laser diode.
A laser diode only lases in a narrow range around its knee voltage. too little and it's just a LED, too much and it's dead.

 

[Orion]

Interesting, luxO! Definitely a learning experience for me. Actually, I was planning on getting a laser driver like this one from Jameco:

It's just an experiment. Just like with the LEDs I've been playing with. Some have worked (and worked well), and some have been destroyed (fortunately those were from Radioshack, before I got a few Nichia).

 

[star882]

Use a one transistor constant current circuit.
Use a capacitor to soft-start the circuit.
Start low and increase until the beam starts to appear.

 

[Orion]

Update, I got that laser diode to work last night, using the driver from Jameco! I don't have a lense to direct the light, but it lights up, and doesn't seem to have any problems. Thanks to all who gave input!

 

[The_LED_Museum]

Congrats!

Now is when you'll need to be careful. The difference in current between Lasing Threshold and El-Asso-Wipo can often be just 10-20%.

 

[Orion]

Thanks! Okay, how do I need to be careful? Please explain further!

 

[The_LED_Museum]

Just don't adjust the current more than a few milliamps higher than threshold - the point at which the laser diode stopped being a dim red LED and started emitting that speckly looking fan-shaped beam.

Once you have the diode lasing, the laser driver circuit should use the diode's feedback (the third lead) to monitor a current source inside the laser diode itself, and automatically adjust the drive current accordingly. For now, the best thing you can do is probably not screw with it once you've adjusted it to obtain actual laser output.

You can always experiment a bit if you get two or three diodes and can afford to let all the magic smoke out of one of them.

 

[Orion]

LOL, Yeah, I'd probably be wise not to try to mess with it anymore!! :-D

I DO have one of those cheap $5 jobs that I may try to stuff one more battery in. If it blows it, . . . . . oh well!

 

[Orion]

You want to know the truth? All I did was to contact the legs to where they are supposed to be on the driver, and hooked up a 2AA battery pack to the positive and negative points on the driver. So far so good. I'm probably under the power setting that it can take, I guess. However, at least it's working.

 

[The_LED_Museum]

The driver probably came pre-set to a current that the majority of inexpensive visible diodes can take. If you're happy with what you have, I'd leave it be.