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How laser diode drivers work; An Explanatory Thread

Hiemal

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Mah first sticky, yay :D
 



Bionic-Badger

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Another "driver" you can use is a transistor-based current sink like this. I use that one quite a bit when I want a voltage-controlled current regulator. It's nice if you want to do I/mW curves or anything where you want to control the current without adjusting a sense resistor/pot directly.

Note that the current sink it isn't a very good "driver" for general use (like in a host), because the transistor is being used as a variable resistor, so its resistance burns off a bit of power. It does function as a good analog driver though.
 
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Aurelienbis

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There is something I'm missing.

I got a laser diode with two pins. + and -
It is supposed to work with 2V DC.

If I take a 2V DC battery, why would I need any kind of regulator ?
Thanks.

Edit : Didn't took in fact that it is a semi-conductor and the current isn't linear to voltage.
 
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The Baron

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I noticed that you said a flexdrive is the best driver right now but from what i have been reading elsewhere that flexdrives are near impossible to get now. Is there a new buck boost driver you would recomend now that the flexdrives are out of the question?
 

tsteele93

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I noticed that you said a flexdrive is the best driver right now but from what i have been reading elsewhere that flexdrives are near impossible to get now. Is there a new buck boost driver you would recomend now that the flexdrives are out of the question?
What do you need it to do?

The benboost works well up to 800mA or maybe 1.2A, not sure. And you can parallel them to double the 800mA.

Wolfman has some very high current buck drivers.

Check out Cajunlasers.com for a good selection.
 

tony1

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Thanks for the lengthy Explaination on the types of drivers and how they work. I have some knowledge, but reading yours makes things clear.

Tony1
 

tsteele93

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Nice update! I would consider adding one more thing to your summary paragraph - battery options. One nice thing about boosts is only having to typically make room for one battery in your design. So for small or short builds, or lightweight builds, or if you only want to have to charge on battery, or etc.. they can sometimes be you only choice of driver.

Except of course when you are dealing with red or ir/green and you are possibly bucking from only one battery...
 

dzrick

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Hello,

My name is Ricardo and this is essentially my first post! So, hello to all and I hope I can learn a little more!

I've read a lot meanwhile, but this post got a lot of my attention and just "got me confidant" to dig into the laser world a little more. :)

I have owned a water-cooled 40W CO2 laser tube, with mirrors and collimating lens (ZnSe), well.. I had a little beast to be true. :D

I still own it, but it doesn't work anymore... Something that usually doesn't happen here destroyed my baby while it was "resting" during transportation from floors. I had it on a chair and a small scale earthquake tilted it to the floor..... yeah I know.. ridiculous... or Karma I don't know!

I used it to cut some Acrylic and some Balsa Wood on my "not-so-user-friendly" homemade XY plotter, but anyway I never really had a chance to do what I really wanted to do.

All this to tell you guys my story and how I've ended up here! :)

Anyway, I've been reading a lot about CC supplies and I'm going that way to drive a Diode Bar, the only thing that worries me are the spikes from the current source... Well, thought I'd tell my story. I'll keep reading a little more, if any questions pop-out, I'll go to the right sub-forum.! :)

Regards and thank you for creating this forum, belive me, it has helped me a lot before.

Ricardo
 

ZekeR

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New to lasers, so sorry if this has been addressed elsewhere...

Is there any reason I don't see the LT3080 or LT3083 mentioned here for linear regulation? They are voltage regulators like the LM317, but their feedback mechanism works differently so you can make them work as current regulators more easily (and with substantially less voltage drop).
 

tony1

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Dear Zeker, ,

I think Lm317 is easier to work with, and much cheaper if I am not wrong.
 

rhd

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New to lasers, so sorry if this has been addressed elsewhere...

Is there any reason I don't see the LT3080 or LT3083 mentioned here for linear regulation? They are voltage regulators like the LM317, but their feedback mechanism works differently so you can make them work as current regulators more easily (and with substantially less voltage drop).
At the higher currents required for high-powered diodes, is not really the IC's voltage drop that matters. If you power a diode with a 4.75 Vf at 2.3 A with any linear driver that is fed by two cells, the IC will basically drop the same voltage (the difference between 7.4V nominal cell voltage and the diode Vf + reference voltage of the IC).

Long story short, linears are fine where the voltage differential is small, but as diodes get more powerful, the power inefficiency of linear divers starts to make then impractical. An LT3083 powering a 445 at 2.3A from two cells won't generate any less heat than a 317, 1084, et . In fact, if the LT3083's feedback voltage is lower, the IC may actually end up dropping more voltage itself, if you think about it
 
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