DVD (22x) Laser diode power up and still not burning or cutting

Hi All,
I was happy to know one can do some tests using the LD from a DVD burner, such a common thing I have researched before setting everything up, I have a little background in electronics so I am familiar with regulators, however, it is the first time for me to use the LM317.
So I wired up the circuit, tried a few resistor values step by step to pimp up the current without damaging the diode. But now I am having a problem, I wired up the circuit yesterday and while trying the LD it always lit moderate-power red, and for once in my tests it lit really good high powered red... to my stupidity I didn't register what actually caused that! or what changes I made at the time to get this output (it was late at night and I need to sleep :tired continuing today, no matter what I do, I can't get this high power again, so far, I have the voltage at ~3.3v, 290melliamps. I don't feel like trying to add more current cuz I don't think I used any less of a resistance yesterday when I achieved this high power!
Any help is really appreciated here :cryyy: I want to start cutting some paper!
FYI: for some reason I have a different looking LD than the common ones in all blogs and tutorials, it's not round, here's a photo of it: View image: 2012 02 26 01 05 03 the circuit I used is the one here:Laser driver - It can be done (third photo with capacitor and 7.2 input voltage) the value I am using is a variable 470ohm pot, and a 2.5ohm resistance) I also added a 1kohm + normal LED in parallel to check on power and I have a 1ohm 5watt series resistor with the diode for safety. (even if I removed it still the same problem)

What i gather from your post is, that you were "testing and learning" which is a good thing.
But just to make sure your LD is still working okay, hook it up to a lab-supply 3V~300mA at this current the ld from a cd burner is pretty bright OR you can also use two AAA's instead. (I use the AAA's leftovers from my wireless mouse).

Secondly the driver could be bad.. Have you tested the current output using a testload?
[+] ---1n400x x4----1 Ohm 5W Resistor--- [-]
*calculate mV reading through the 1Ohm resistor.
mV=mA

Hi, thanks for getting back on this, I am pretty worried about connecting it directly to batteries (excess current could put an end to it! right?) I actually did the diode trick the first time before connecting the diode ) I did it again now, the reading is around 240 milliVolt, but why is it that you say that mV=mA?! cuz of the 1ohm value in case I am not wrong?

EDIT: I now just pushed the amps a little higher to 320mA, still nothing, I am suspecting something is wrong cuz the light intensity doesn't 'significantly' increase from the 170ish till the 300ish mA range! and I still can't seem to figure out how I achieved yesterday intensity, this is driving me a little crazy!

I would make a good bet that you have killed your laser diode. I'm not sure how you hooked it up originally but not all lab supplies are meant for doing laser diode.
Why not send a picture of your lab supply and set up that way we can have a better idea of what exactly you're doing.

I don't have a lab supply, I have all the components (LM317 circuit) on a bread board, I was thinking the same that I might have ruined it, but then again why does it still work (I can still see the red light)??

I don't have a lab supply, I have all the components (LM317 circuit) on a bread board, I was thinking the same that I might have ruined it, but then again why does it still work (I can still see the red light)??
here's a photo of it working with the unexplained low power: View image: 2012 02 29 00 26 57
another one with the amp reading and small messy circuit: http://postimage.org/image/s7hcpqbxh/

You need a focusing lens.

kowado55 said:

I don't have a lab supply, I have all the components (LM317 circuit) on a bread board, I was thinking the same that I might have ruined it, but then again why does it still work (I can still see the red light)??

Click to expand...

Actually, when you LED your Laser diode, the extra current melts components in the diode causing it to fail to laser properly, your end result being a red light.

btw, How hot does your diode get?

Ghostchrome: Tried that, nope , also if you check my first post, I was able to get much more light from it at some point, I just don't remember what is it that I did differently!
Seoul_lasers: hmmm...it doesn't get hot actually! :undecided:

Seoul_lasers: Are you sure about this?? a laser diode can just be a LED? wouldn't over-current just ruin it totally so it won't work at all? I was just wondering if you had past experiences with this.
So if I go and buy another diode or extract one from another DVD writer, is there a way to use the already built in circuit of the DVD write to make sure the LD will be powered properly with maximum power and longest life span??

There's something I noticed about the DVD laser diode, it had three pins, but unlike the conventional pin configuration of the common LD (Gnd, LD, case/body) this one has: Gnd, CD & DVD... thought it's worth mentioning!

kowado55 said:

Ghostchrome: Tried that, nope , also if you check my first post, I was able to get much more light from it at some point, I just don't remember what is it that I did differently!
Seoul_lasers: hmmm...it doesn't get hot actually! :undecided:

Click to expand...

It's possible you LEDed your laser diode. It's possible to fry them and still have it be able to produce a dim light... Hence the name LED.

You need to use a test load before you hook the driver up to the laser diode.

And lastly, you need to make sure that you discharge the capacitors in your driver before you hook the driver up to the laser diode, otherwise you will LED your diode. This has to be done every time.

But back to my original post. The picture of your diode that you posted; it looks different because it is still inside its heatsink. You need to get it out, press it into a laser diode module, and install a lens that will let you focus your laser to a point. You cannot burn if it's not focused.

One more thing, this diode is red and won't be able to "cut white paper". Red is good for burning darker colored stuff.

I think you have killed the diode ... It's led now, nothing you could do to make it laser brightly again...

the other diode is a flat plastic diode ... don't bother with it it's a lower power and heatsinking it would be a problem . :beer:

remember to always discharge the output caps of your driver BEFORE connecting the laser diode to it.

kowado55 said:

Seoul_lasers: Are you sure about this?? a laser diode can just be a LED? wouldn't over-current just ruin it totally so it won't work at all? I was just wondering if you had past experiences with this.
So if I go and buy another diode or extract one from another DVD writer, is there a way to use the already built in circuit of the DVD write to make sure the LD will be powered properly with maximum power and longest life span??

Click to expand...

As was explained to you, when you kill your LD, it can go 2 ways, LED.. meaning you have damaged the die (part in the diode that assists with lasing) or a complete failure, no light.

Diodes that LED usually get extremely hot as they are wasting excess power.

Hi all, thanks for your feedback, I have some things to say...

1. Yes, I discharge my cap before connecting the diode
2. I have got myself another DVD RW drive, but I don't want to extract the LD from it yet, I am thinking maybe there's a way to use the already built in circuit to ensure correct power
3. I have quickly tested the new LD while it's in the DVD circuit (its pins are still accessible) using low current, I started from 10mA and gradually increased the current using the pot and reached gradually to 300mA and I can see the same behavior! I am thinking there must be something wrong with the driver circuit it's the only cause left, right?!
4. Still neither the old one nor the new became hot during these tests

please post a photo of your driver's setup