Help for a newbie... 250~350 mW red laser

[LazerDragon]

OK, so I'm a complete noob when it comes to lasers, but I'm trying to build a working constant current driver using the diagram from this website: "Laser driver - It can be done". I've got a couple of issues though... 1) I harvested a laser diode out of a Philips SPD2513BD/17 DVD/CD Rewriter and I have no idea what the Wattage of the diode is. I looked a bunch of websites for the specs of the diode and the Rewriter itself. The reason I'm guessing this is a 250~350mW diode is because this website has some info on the stuff "Laser Diode Power Output Based on DVD-R/RW specs" and the DVD/CD Rewriter is x20 speed, so using the info from that site I guessed 250~350mW. 2)If that is the power of the diode wouldn't the CCD be too strong for the diode and blow it (again' I'm a newb with these things so any information is great)? And lastly... 3) I'm a bit confused... if the LM317 is a voltage regulator (the voltage the same) why is the driver a Constant Current Driver?

I left two pics of the diode I'm hoping to use if that helps...
Thanks for the help and this is my first post so tell me what i can improve,
LD (LazerDragon not Laser Diode):yh::yh::yh:

 

[IsaacT]

What you have there is an open can 650nm laser diode, so yes it should be able to run off of 250-300mA. the LM317 will allow you to set the current by soldering resistor(s) in between the Adjust pin and the V-out pin. I don't know too much about Electronics(yet), but I have made a ton of LM317 Drivers.

Since R=E/I, where R is resistance, E is Voltage, and I is current, and the LM317 uses 1.25V:

R=1.25/.25, which comes out to 5. So you need 5 Ohms, which can be attained by soldering two 10 Ohm resistors in parallel between the Adjust and V-out pins on your Voltage Regulator.

Make sure when you build your laser to heatsink both the driver and the module holding your diode, as it will heat up pretty quick without it. And heat is bad...very. bad.

Next time you have questions or need Help with a laser build, you should put your thread in the Tutorial, Help & Repairs section of the forum, as opposed to the Rules & Stickies section. It helps a lot both with keeping our forum clean and easy to navigate, as well as helps your questions get answered, since people don't view this section as much.

Hope that helps Good luck on the build,
Isaac

PS-Please don't go make another thread in Tutorials, Help & Repairs. If you really want one in there, try PMing a mod. Multiple threads about the same info is not looked on very kindly here(or in any forum for that matter).

 

[LazerDragon]

Haha...ya... i already made another thread and realized a bit too late what i had done. I honestly wish i hadn't and won't do it again but its my first thread so i'm hoping i won't get too much grief from it.
How exactly am i supposed to heatsink the driver?
And I was hoping to use a 9 volt battery but i'm slowly realizing that won't be a great idea (with the heat and all...) so what should i use as a power source?
What exactly is an open can laser diode and do you know what mW that would be? Sorry for all the questions and thanks for the help...
~LazerDragon

 

[hakzaw1]

you may also want to search ESD- unless you were wearing a wrist strap when those pics were taken that diode may already be a LED.


Wanna is giving good advice- you need to match your threads with the proper board.

You can PM daguin and ask for it to be moved--n/p

 

[IsaacT]

The search bar is definitely your friend here...if you ask too many questions without searching the forum first, you will end up being neg repped and will be learning the hard way. *hint* most of your questions are fairly easy to research *end hint*

Now, because it will not harm me in the slightest to throw out my thoughts, here are some quick answers to your questions:

Heatsink Question: Search the B/S/T or Laser Pro Shop for "Heatsink". they come in two varieties: "Direct Press" or "Fit for Aixiz Module". Easiest for you IF YOU HAVE and Aixiz module will be the "Fit for Aixiz" variety, whereas if you don't have an Aixiz Module, you will need a Direct Press Heatsink. The idea is for the Heatsink to help the diode stay cool by conducting heat from the diode to the air.

Power Supply: a 9V will work but will generate a lot of heat due to how much power the LM317 is having to absorb(like 5-6V of unneeded voltage will be turned into heat). If you look at the link in my sig to the DIY 405nm Lab that I did, you can see I used a Wall Transformer thing I bought at Fry's. I HIGHLY suggest it if you want to do a lab style laser. Other options are buying a battery holder or something and using a less voltage battery.

What is an Open Can LD? There are Closed Can Diodes and Open Can Diodes. Closed can diodes have the front part completely enclosed with a small window of glass whereas the Open Can diodes look like what you have, with all the parts exposed to the elements. I would run it around 250mA and expect 200-250mW of power from it, but you never know...every diode is going to exhibit different amounts of efficiency so "ya never know what ya gonna get".

Good luck,
Isaac

 

[LazerDragon]

Thanks for the help. I'm pretty sure Hakzaw1 was right when he said that the diode is dead because it's been sitting in a DVD Rewriter in a computer that's pretty old (in terms of a computer's life). I guess now I'll just have to buy a different diode. Out of curiosity, how could you tell the diode was ruined?
Thanks for the help, again, and if I have any more questions I guess I'll post them (but, don't worry, not before making sure I can't answer it on my own)
~LD

 

[IsaacT]

Don't just toss out the diode...try soldering some leads on to it and connecting it to the driver you are making. Worst case scenario is that it is, in fact, dead, and you have to unsolder it and solder a new one.

For Laser Diodes at a good price I would suggest Cajunlasers.com

 

[lasersbee]

I was recently informed that any new members that need help getting answers
to their questions can contact/PM member Eudaimonium directly here..

PM Eudaimonium

He has graciously offered to answer ALL questions from ALL new members...


Jerry

You can contact us at any time on our Website: J.BAUER Electronics

 

[IsaacT]

Tsk, tsk Mr Lasersbee.... :eg: although I suppose he DID ask for it lol.

 

[LazerDragon]

Ok...I'm slightly confused with this: so if a laser reads 300mW in power and has an efficiency of 1 then the current needed to supply power to the laser is 300mA? Does the voltage coming out of the LM317 stay constant too, because to not exceed 300mW you would need to keep the voltage at 1V, or is most of the power supplied from the voltage turned into heat in the diode(because the diode needs 3 volts to operate{based of the laser driver website in the first post}), which is why it requires a heatsink. Also, won't the Pot from the driver add 100 ohms(max) to the resistance, because it is in a series, not a parallel? Plus, doesn't the LM317 operate with 3V, so why are you using the least amount of voltage that the LM317 takes(all of this is from the laser driver site so if it had any misinformation I would like to know).
If it would be better for me to just PM this to someone(e.g.Eudaimonium) instead of putting it on this thread (because I feel I am asking extremely beginners questions and I'm pretty sure its being frowned upon) feel free to tell me.
Thanks for all the help
~LD

 

[lasersbee]

An LED or a LD is a Current device.... It requires
a certain current to function as designed. If you
increase the voltage to the device the current will
increase.

The problem lies in Ohms Law and the relationship
between I E R (Current Voltage Resistance)
Changing any one of them makes a change in one
or both of the others. That is basic electronics 101...

I would suggest that you Google "Ohms Law" to get
a better understanding of how it works or contact the
member that is offering help by PM...:beer:


Jerry

You can contact us at any time on our Website: J.BAUER Electronics

 

[LazerDragon]

I meant more around the lines of why do you always reference 1.25 volts. I understand Ohm's Law. If the resistance between the output pin and the adjustment pin of the LM317(from the driver) changes then does the voltage change as well as the amperage, and if it does how can you calculate it...