dvd laser driver

[USAbro]

Hey guys, been working on making a dvd burner laser and just had a question. For the driver I'm using http://laserpointerforums.com/f42/diy-homemade-laser-diode-driver-26339.html

But is there a way to make the circuit without the pot. Radioshack doesn't keep this in stock and I know I could buy it online but is there another way?

I've got the diodes, the lm317t, the capacitor and even the resistors, just not the pot.

Any help appreciated.

 

[USAbro]

Also, the diagram on that page is confusing, does anyone have a video of this build?

 

[Mattronium]

First of all, it is frowned upon to double or triple post unless it is for bumping (your) sale thread (within reason). If you have to add something you forgot, you can use the edit button and add it to your original post. Some put it at the bottom of the post after putting EDIT: there to let others know that it is added.

Second. Look for yourself! Google or forum search. Ie.

https://www.google.com/search?q=lm3...e=univ&ei=PC9dVKTmIoe7yQTTgYLwDg&ved=0CCUQsAQ
LM317 Current Calculator - Electric Circuit

Just remember to use the correct pinout:
https://www.google.com/search?q=lm3...&ei=yC9dVMTpE4K3yQT2xoHAAg&sqi=2&ved=0CB0QsAQ

EDIT: You shouldn't need the pot as long as the resistor you are using is correct. The pot is there so that you can adjust the current in smaller increments or easier.

 

[USAbro]

I'm sorry, just really confused, if I leave out the pot than do I just connect the other two resistors end to end? I'm not that great with with kinda stuff so any help is great!

 

[ChaosLord]

Use the links Mattronium provided to calculate what resistance you need to replace the pot.

 

[upaa27]

Schematic says to to stick battery positive to lm317 in. Stick battery negative to diode cathode then stick a capacitor pin next then laser diode anode. LM317 out goes to pot pin 1 or 3 and 2. Pin 1 or 3(whichever you dint stick to the lm317) goes to the 4 ohm resistor. Lm317 adj. goes after that resistor. Then stick resistor unused pin to diode anode, then stick to capacitor unused pin. Then that sticks to the laser diode cathode.

 

[USAbro]

Thanks guys, I did it. First time round I did it wrong, the circuit blew the capacitor. This time it works. I modified the circuit to not use the pot. I couldn't find it at Radio Shack and am too impatient to order online. Resistors leave the adjust side of the regulator and enter the out side. Both soldered to be a pair. Can this drive a 16x dvd burner laser you think. I'm not sure how to measure the mah output but I'm using the 10 ohm resistors, and no pot.

 

[upaa27]

Ammeter capable of 5 amps or more. Put a load in series with it though so that there is no short.

Glad to hear it doesn't blow the cap anymore! Have you tested if it works yet though?

Also keep in mind that the pot is for output adjustment so without it your LD will be receiving all the power and therefore you will probably have to put one on anyway.

 

[USAbro]

I may add that later. Yes, so far I have tried it and it drives a 30mw 660nm diode fine.