DVD burner laser pinout question

[large_ghostman]

hello. i taken apart a old DVD burner from a disused pc, i got the laser out ok and it has 3 pins but i havnt been able to find or figure out how to connect it up only thing i found said to use old pc power supply and use yellow wire for gnd and red for positive but on my psu yellow is 12v and red is 5v so that dont make sense to me! i dont want to do anything dodgy or dangerous with it i have a cool project in mind but i need to get a dvd laser working can anyone help?

 

[Reloadron]

Using Red (+5 Volts) as common and Yellow (+12 Volts) as high gives you a 7 volt supply or 12 - 5 = 7. If you have a meter give it a look. Sorry, can't help with the LASER.

Ron

 

[ghostman11]

thank you for that ron! thats pretty neat! i will have to try it out

 

[Reloadron]

Give it a shot lil' Ghostman. Just make sure you don't get the PSU Black (Common) in the mix in a wrong way.

Ron

 

[picbits]

Don't hook it up to any power supply - you'll blow it straight away.

You need a current limiting supply for laser diodes - lots and lots of information on here : https://laserpointerforums.com/

Also be aware that an infrared laser from a writer has enough power to instantly blind you and you won't even see it coming ......

 

[ghostman11]

thank you for the info picbits i will pass it on to LG. not so sure i want him messing with one now!!

 

[DerStrom8]

They can be dangerous, but just don't ever point it at anyone (including yourself). If you use the power supply circuit that was connected to the laser while still in the PC, you shouldn't need any more current limiting--it should be built-in. However, if you've changed anything else with the circuit, then picbits is right--you'll need extra circuitry.
As always, be very careful when playing around with lasers. DVD burner laser diodes have enough power to literally burn things. Not really something you should just play with. You have to know exactly what you're doing. However, if you have adult supervision, it may be okay to experiment with. Here's a diagram of a power supply you can build yourself that should be ok:

**broken link removed**

And by the way, 3 volts should be enough to power your laser diode, 3.6 if you want optimum performance.
I hope this helps. Good luck, and stay safe!
Regards,
Der Strom

 

[ericgibbs]

hi J,
Many lasing diodes have a built photo-detector, the third wire, it purpose is to provide feedback of the light intensity so that it can be part of a current controller.

EDIT: my best advice would be to not let 'L' play with lasing diodes.

EDIT2:
Link showing the current limiter
http://www.k3pgp.org/laserbias.htm

 

[ghostman11]

kind thanks to you all! just the info we looked for and couldnt find! so just to recap although the diagram says 7.2 volts optimum its actualy around 3v optimum? thanks for the feedback circuit diagram that might well be useful as for the application......... LG is taken with the new CNC mill and obviously i am not letting him near it! so he has cobbled together a contraption from 2 very old and broken inkjet printers and has a kind of cnc machine of his own, he wants to try and make a kind of etch a sketch with a laser! the actual laser will be enclosed and i milled him a heat sink for it. once its mounted on his contraption he wont actualy be able to get to the light as its set around 15mm from the base of his machine. plus he wont be playing with it without me around. i am somewhat dubious with him messing with stuff like this but i am also more than a bit curious as to what we can get this thing he has made to do if we manage anything i will post some pictures

 

[DerStrom8]

kind thanks to you all! just the info we looked for and couldnt find! so just to recap although the diagram says 7.2 volts optimum its actualy around 3v optimum? thanks for the feedback circuit diagram that might well be useful as for the application......... LG is taken with the new CNC mill and obviously i am not letting him near it! so he has cobbled together a contraption from 2 very old and broken inkjet printers and has a kind of cnc machine of his own, he wants to try and make a kind of etch a sketch with a laser! the actual laser will be enclosed and i milled him a heat sink for it. once its mounted on his contraption he wont actualy be able to get to the light as its set around 15mm from the base of his machine. plus he wont be playing with it without me around. i am somewhat dubious with him messing with stuff like this but i am also more than a bit curious as to what we can get this thing he has made to do if we manage anything i will post some pictures

That's quite an interesting idea...

I believe the 7.2 volts is optimum for the input to the LM317, not the input to the laser diode (unless I'm reading it wrong). Then the LM317 regulates the voltage to whatever you choose it to be. The higher the voltage, the hotter and brighter the beam will be, but you also risk burning out your diode. Some people have used pulse systems so that they can put more voltage/current through the laser, but I don't know how complicated that would be.
You'll also need to figure out the lens system. There are setups you can buy online called Aixiz modules. They are designed for this type of diode and have a way to adjust the output beam. It may be worth looking into getting one of those. Just google for them and you'll get a bunch of hits.

Good luck with the project! And keep us posted
Regards,
Der Strom

 

[ghostman11]

cheers again for the info. i didnt figure in any optics :S so i will have a google see what i kind find him