DIY Homemade laser diode driver

[Gazoo]

li-ion are rechargeable lithiums. Like these and you would also need a li-ion battery charger. DX does have them too.

http://www.dealextreme.com/details.dx/sku.6240

 

[Skram0]

Just don't be in a rush for the items if you order from Deal Extreme. Give yourself about a 3-4 week lead time for the order. A slow boat from China takes time, ya know.

 

[stump56]

i think i am going to go for the 6 cell method i already have a 4cell holder so ill just go to rat shack and get one that holds two tomorrow and add it on with some double sided foam tape since they dont carry a 6 cell for AA

 

[stump56]

man this is so frustrating . I just used a 9v source and i got 1.25v across the adj. and out but when i checked the current its still 208ma i don't understand what is wrong its not the 317 because i changed it out same results.

 

[Gazoo]

I checked and you are right...not that I doubted you...lol. It's just that I am really surprised they don't have any 6 cell holders.... Anyway, the regulator will behave much better with 6 cells.

 

[Gazoo]

Here is a good link to help you understand how the LM317 works and to double check your wiring.

http://users.pandora.be/davshomepage/current-source.htm

As long as you have everything wired up correctly, you should be seeing 250ma's. Check the resistance of the 5 ohm resistor with your ohm meter. I really don't know if a 10 ohm resistor is going to be low enough. As I recall Chimo suggested using an 8 ohm resistor as a load and it worked.

 

[stump56]

Well if it makes you feel any better you said AA or AAA and they had a AAA 6cell. lol

 

[Gazoo]

lol....ok...but it is not listed on their website

 

[stump56]

well can anyone tell me what i have wrong i cant figure out why my readins arent right with this set up I get 1.9v and 189ma

 

[stump56]

update when i use the unfused side of the dmm i get 250ma why is this different. shouldnt the out voltage be higher than 2

 

[mikfaina]

Hi Can I construct a laser driver with components I can find In copmputere pieces? RESistors ANd capacitors I think yes but what about the voltage regulator?? there is another way to have the same effect??
I have a 16x Sony diode.

I pull off this circuit from a laser driver I had yuo think I can fit with my new diode?

 

[rubberband]

is there a way to discharg your capacitor before attacing your diode. i used it on a 5 mw laser and when first connected it gets really bright for a second and then dims to normal. i think that this spike will kill my diode so please if anyone can help it would be great.

thanks alot,
mitch

 

[Gazoo]

You can discharge it by shorting it, of course with the power turned off.

 

[rubberband]

yea tryed thet but still the same.

but this varience is only visable when the current is very low is this a sign of a problem in my circut or is this normal?

Thanks,
MItch

 

[Gazoo]

I notice a spike when I turn on my power supply on my labby. But since the laser is current adjustable, I always make sure the current is turned all the way down before I apply power. If you are using batteries, they might be sagging quickly...it's all I can think of off hand..

 

[rubberband]

k thanks alot

it is off batteries

mitch