DIY Homemade laser diode driver

[jaap75]

ok, so volage is not the problem. Then it must be the current that causes my diode to not give enought mW

And i thought windowless was the same as open can, Because the can is "Open" without an window.

Anyway,

My ir diode is: "Windowless"
And my Red diode is: Closed can with window

My doide should be able to burn matches right? It's an 18x speed harversted from an lg burner.
When point it at a match the match barely geets hot.

Thanks, Yoeri

 

[rkcstr]

jaap75:

You're using 2 CR123 batteries, right?

If so, then at 250mA (what 2 parallel 10ohm resistors gets you), your diode should definitely have enough power to burn. Do you have it an Aixiz housing with focus? Make sure you focus it to a very small point, otherwise it may make it difficult to heat anything up enough to burn.

 

[jaap75]

Yes, I'm using 2 Cr123 rechargeble battery's en two 10ohm risistors in parralel.
And i'm also using the aixiz housing with focus, and yes it's also a very small point.

But no heat built up at all :-/

Maybe with your driver it will work
We'll see

Thanks, Yoeri

 

[jaap75]

Hi all,

good news

This afternoon i was playing a little bit with my laser, Trying to get a better focus.
Then i tried to focus from 10cm distance. ( Normally I alway's focused from about 10 feet.) I didn't there would be any difference but the dot became really small.

So i tried a lighting match, And it worked ;D I can also pot balloons and even light a fuse

I'm really happy with my laser, and i want to thank the forum for the outstanding information and tutorials.

Thanks, Yoeri

 

[rog8811]

Damn! I was determined to get the 900th post on this thread...
...... it was nice that it was taken by someone very happy with the help he got here.
I wonder how many DDL LM317 drivers have seen the light of day because of this thread.....

Regards rog8811
*is poised for the thousandth post* :

 

[chaoslaser]

wow... A TON of information. Cant wait to put one together myself.

BTW rog8811 you can still try for post #1000...

 

[Fusion2004]

So from what I understand, if complete the circuit with my DMM instead of a laser diode, I should read 2.5V, correct?

I haven't received my diode in the mail yet, but I bought all the other components, along with a breadboard at my local radioshack. I put together the circuit, excluding the diode I don't have, and hooked one end to a 4 AA battery holder with fresh lithium batteries that reads 7V by itself, and on the diode end I just hooked up my DMM. However, instead of reading the 2.5V I thought I was expecting, I read a constant 6.3V.

So am I just an idiot, or is something horribly wrong?

 

[jayrob]

That's normal without the diode. What you want to check, is that it is putting out the correct current. The LD will take what ever voltage that it needs. You don't have to worry about it reading 6 or so volts without the LD connected...
Jay

 

[Fusion2004]

Thanks, jayrob.

I have two more questions for you, if you don't mind:

Can I check the current without a diode? From what I understand, I would have to insert the DMM in the positive connection between the diode and the rest of the circuit. Please correct me if I'm wrong.

And the other important question I have is this: DDL says to make sure the pot is turned to maximum resistance when you first hook up the diode. Is that the side the two connectors attached to the LM317 are on, or the side the connects to the resistor?

 

[jayrob]

If you test the driver current before you connect the LD, then you don't have to worry about turning the pot to max resistance. Just have it set at the current you are after. The one thing to look out for, is to make sure that you discharge the cap (by shorting the wires together) before you connect the LD. Otherwise, you will kill the LD before you even get a chance to test it.

As far as testing current, there are several ways to do this. It is best to use a load, and connect your DMM in-line on the positive lead. I am really not the right guy for this question. I have a bad habit of 'cheating' with the current test. I use my DMM on the positive and negative leads. This is not the best way to measure current, because it is 'shorting' the DMM, and probably could fry the meter. But, it is an accurate reading. My meter has safety features built into it so that it won't fry...
Jay

 

[chido]

Look at this thread for testing your driver without risking your laser diode.

 

[trublu832]

Is 9 volts critical for a blu-ray driver? Will 6 volts work? I only have enough real estate in my flashlight/host for 2 cr123's and a driverboard.

 

[rog8811]

2 cr123's

6volts won't allow the reglator to function properly, change those for RCR123A's and you will have 7.2v which is still borderline for LM317 use when you assume
4.5v for the LD + 3v for the regulator..... you may do better using a 7805 driver circuit.

Regards rog8811

 

[trublu832]

Thanks, RCR123's is actually what I meant and I did get around 7.2v when tested. Upon closer inspection, I may be able to fit three RCR123's and an SMD driver board inside, would an SMD board have possible heatsinking issues on a blu-ray driver?

 

[rog8811]

would an SMD board have possible heatsinking issues on a blu-ray driver?

With 3 RCR123A's (10.8v) the regulator will need to dissipate 3.3v, at that it will warm up, the SMD ones sold around this forum should cope (they have a thermal cutout for over temperature) but if you have room it would not hurt to glue a small aluminium heatsink to the reg.

Regards rog8811

 

[rkcstr]

Thanks, RCR123's is actually what I meant and I did get around 7.2v when tested. Upon closer inspection, I may be able to fit three RCR123's and an SMD driver board inside, would an SMD board have possible heatsinking issues on a blu-ray driver?

I don't think it'll heat up too much... I've never felt my driver (the one I sell) at 38mA ever feel like it's heating up, but I could do a test and see what happens with 3x lithium rechargeables and get back to you.