Laser Driver (DDL) Schematic

Briellesdaddy09 · Jan 21, 2011

Hello everyone this is my first post as i just joined yesterday. I have to say I love the forum. I have always really liked lasers but just recently have made a few attempts at making my own DVD burner laser. Unfortunately I made three failed attempts to date until now finding this forum. So anyways now i have successfully built a laser from a 24x LG DVD burner (GH24) and a driver i believe it is a DDL type and now i am just waiting on a AIXIZ Module to finish my project. Anyways the reason for this post is to show you guys this Schematic I made with EXPRESSPCB of the type of driver I made to see what people think and if everything is wired correctly and possibly any suggestions or whatever. Well anyways here it is I hope you all like...
Sorry about quality of image had to save as xps then convert to image so i could upload it.

Components:
1x LM317T
2x 10 ohm Resistors (in parallel)
1x 1k ohm Pot
1x IN4001 Silicon Diode
1x 47uf 35w Resistor

anselm · Jan 21, 2011

Looks fine to me...
What are the values of R1, R2 and the potentiometer?
That circle close to the output is a capacitor, yes?

Briellesdaddy09 · Jan 21, 2011

Yes it is a Capacitor a 47uf 35w cap. Thank you i forgot to say what everything was exactly i will go ahead and add that info in now. oh and those are 2x 10ohm resistors which from what i read makes it 5ohm since in parallel.

Briellesdaddy09 · Jan 21, 2011

oh yeah and i used a 1k ohm pot that was the smallest i could find at my local radio shacks I also bought a 25 ohm but its so damn big. Which do you recomend i use>?

sampson · Jan 24, 2011

Briellesdaddy09 said:
oh yeah and i used a 1k ohm pot that was the smallest i could find at my local radio shacks I also bought a 25 ohm but its so damn big. Which do you recomend i use>?

Your 1k pot will work though if it's not a multi-turn pot it may be difficult to get the value you want. In that setup your R1 and R2 will be your safety; your resistance will never go less than 5ohm even when your pot is 0. you have a cap and diode for safety; looks good. With that driver you should get 0-250ma adjustable output.

i recommend using a test load before hooking up a diode. Also remember to short out your cap before hooking up your diode.

reference here: Laser driver - It can be done

Bionic-Badger · Jan 25, 2011

Before you spend too much more effort on that, try using Eagle for your PCB layout. It's free, and you'll get a lot more mileage out of it than ExpressPCB, because it exports PCB masks that are compatible with all PCB manufacturers, not just ExpressPCB.

Also the workflow is probably easier (unsure, since I haven't used ExpressPCB). You create the schematic first, and then PCB layout is created from that. The schematic is a lot easier to analyze than the PCB traces.

jib77 · Jan 25, 2011

1)Your traces are way too small ... always use the largest trace you can get away with in the space you have.
2)Use 45 degree traces to turn corners ... you have too many unnecessary right angles.

ExpressPCB is very expensive for what you get. Generating your own gerbers gives you the flexibility to use any fab you want for much much cheaper(Like the one in the link on my Sig).

I agree w/ Bionic-Badger ... learn Eagle PCB, its worth it. Its a bit of a learning curve, but this circuit is perfect for learning. Then you too can do stuff likes this:

Tonga · Jan 25, 2011

jib77, this is a laser driver that you built? If you don't mind me asking, what are the dimensions and specs for this board. Also this is really nice work, do you sell these?

TTerbo · Jan 25, 2011

To make a simple laser driver you really only need 2 things (3 if you wanna be super safe)
LM317, and a resistor to set the output, and then a cap on output to be supersafe

Bionic-Badger · Jan 25, 2011

Oh yeah, and if you need your PCBs fabbed for a decent price, try BatchPCB. After the setup fee ($10), it's $2.50 per sq inch for two layer, silkscreening, any number of vias, any shape, multiple designs in one, etc. I have yet to use their services, but it's really not too bad for a pretty professional final product.

For your DDL circuit, try cramming those components into a plated perfboard rather than a PCB.

jib77 · Jan 25, 2011

Tonga said:
jib77, this is a laser driver that you built? If you don't mind me asking, what are the dimensions and specs for this board. Also this is really nice work, do you sell these?

That was a board testing an idea I had about using lower power rated pots in a modified DDL circuit. I gave up on pots and Im working on a cheap fixed version, just the NCP1117, 2 caps, and 2 set resistors. Im getting 1.33A max out of it. I call it the "PipSqeak" cause it so small, 14mmx10mm. I have enough boards/parts for 6 of these @ max setting, Im testing it today, if everything checks out ill put up a thread in the FS section:

Bionic-Badger · Jan 26, 2011

Considering how many people want their drivers pre-set anyway, it's not a bad idea to just plant resistors on the board instead of an adjustable pot.

Briellesdaddy09 · Jan 26, 2011

sampson said:
Your 1k pot will work though if it's not a multi-turn pot it may be difficult to get the value you want. In that setup your R1 and R2 will be your safety; your resistance will never go less than 5ohm even when your pot is 0. you have a cap and diode for safety; looks good. With that driver you should get 0-250ma adjustable output.

i recommend using a test load before hooking up a diode. Also remember to short out your cap before hooking up your diode.

reference here: Laser driver - It can be done

Thanks for all the info on my driver! I did use a multi-turn pot after finding out the hard way how bad the single turn pot was that i originally used. The single turn pot only worked at the final 5 degree of the turn. lol So i removed that and replaced with a multi turn which worked out way better. Also just wanted to say that i was just using ExpressPCB to make a schematic for reference when i made my board i was gonna order till i saw that they wanted 60$ just for that one driver board which is beyond insane! I also ended up removing the 2x10ohm resistors and using 1x 2.2 ohm resistor cause the diode i had (a flat 3 pin plastic type red diode from a HP 24x DVD1260i) ended up being way more powerful than I had ever imagined the little flat diode could ever be. I now am running it at 380ma 3.2v, I don't know how much power i am getting since i can't really afford a LPM but i am able to burn the crap out of my desk (which is black) and anything else that gets it its path! lmfao I am really enjoying this hobby a lot. well thanks for your thoughts on my driver i appreciate it all.

sampson · Jan 26, 2011

Briellesdaddy09 said:
Thanks for all the info on my driver! I did use a multi-turn pot after finding out the hard way how bad the single turn pot was that i originally used. The single turn pot only worked at the final 5 degree of the turn. lol So i removed that and replaced with a multi turn which worked out way better. Also just wanted to say that i was just using ExpressPCB to make a schematic for reference when i made my board i was gonna order till i saw that they wanted 60$ just for that one driver board which is beyond insane! I also ended up removing the 2x10ohm resistors and using 1x 2.2 ohm resistor cause the diode i had (a flat 3 pin plastic type red diode from a HP 24x DVD1260i) ended up being way more powerful than I had ever imagined the little flat diode could ever be. I now am running it at 380ma 3.2v, I don't know how much power i am getting since i can't really afford a LPM but i am able to burn the crap out of my desk (which is black) and anything else that gets it its path! lmfao I am really enjoying this hobby a lot. well thanks for your thoughts on my driver i appreciate it all.

Glad that you got everything working well! You've got some power there so make sure and wear safety glasses with that thing! If you don't have any you can get some decent protection for red @ $30 here:

powerfulpurchase items - Get great deals on Electronics items on eBay.com!

Here is a review that Kenom did on those glasses:

http://laserpointerforums.com/f52/e...nm-580-760nm-powerfulpurchase-ebay-55221.html

I own those glasses based on that review; I've been very happy with them and will likely purchase another pair. Be safe and have fun!

Laser Driver (DDL) Schematic

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