DIY Homemade laser diode driver

[xinf3]

I completed my driver, had a pic but i'm not yet able to post pics.
A very big thanks to Daedal; your guide was very well written and a breeze to follow.
Also, thanx to others that added info.
now, all I need is some LD's to power up

 

[Daedal]

Hey ive just got a few quick questions

1) Im a little confused at where to place the DMM in the circuit to measure voltage and current. Can we just attach the terminals of the DMM to the wires that would be going to the laser diode to measure the voltage going to the diode before we attach it? and where would you place it to measure the current?

2) I was wondering... we are aiming to get 2.5-3 V to the LD and 250 mA. but if you plug that into P = VI you would get about 750 mW? isnt that a bit much, or am i calculating wrong?

3) I think my circuit is not correctly wired (or im not measuring at the right spots) - when i measure the voltage, it starts at about 2.5 and keeps going down and down and down (even if i unplug and reconnect the terminals of the DMM). but if i measure it again a few minutes later, it goes back to about 2.5 v and keeps going down and down.. if thats just a crazy result, dont worry about it, im going to make another circuit and test it out - any answers to the above two questions would be enough

thanks a lot for your help guys

dil

Dil, your calculations are right, but your other questions have been answered previously...

--DDL

 

[Daedal]

If I put the capacitor in parallel with the battery before it goes into the lm317 would that still be effective and do an ok job of filtering any spikes?

It would do the same job of dulling some of the spikes from the battery(s) but the LM is better off with some capacitance after it... so the back of the LD is the best spot.

--DDL

 

[Daedal]

I completed my driver, had a pic but i'm not yet able to post pics.
A very big thanks to Daedal; your guide was very well written and a breeze to follow.
Also, thanx to others that added info.
now, all I need is some LD's to power up

Congrats

I'm glad you liked the guide and I hope to be improving and adding to it soon

--DDL

 

[philguy]

Oh, so the Daedal-circuit is the Senkat-Diy-Kit...thought we finally got a good pulsed-one

 

[a_pyro_is]

Daedal,
How's the new circuit with that LDO regulator coming?

 

[Daedal]

It works... with a very low dropout too

I'm worried about posting it online for fear of all the confusion it'll drag on considering it's a negative regulator, but it's doing a great job as far as I've tested

--DDL

 

[the_stark]

Daedal, I've gotta thank you for writing out this circuit. I've know some basics in electronics, but still learning. The schematic on the first page really helped me, and now I'm gonna get the parts to build it! Then some LD's from the GB and hopefully I'm ready to light some matches!

 

[Gazoo]

Welcome to the forum.. Yeah...you will definitely be lighting some matches as well as admiring the beam..tons of fun.. ;D

 

[chimo]

1. You don't suppose that people will ask you questions on it......

2. And then you and/or others answer those questions......

3. And then a little later someone asks the exact same questions........

4. Goto 3.

It works... with a very low dropout too

I'm worried about posting it online for fear of all the confusion it'll drag on considering it's a negative regulator, but it's doing a great job as far as I've tested

--DDL

 

[a_pyro_is]

Naw, it could never happen.

 

[Daedal]

Daedal, I've gotta thank you for writing out this circuit. I've know some basics in electronics, but still learning. The schematic on the first page really helped me, and now I'm gonna get the parts to build it! Then some LD's from the GB and hopefully I'm ready to light some matches!

That's excellent Let us know what you come up with

--DDL

 

[rubberband]

i am al little confused with the connection of the 3 pin regulator what does the 3rd pin do and is there like a screw on it like on a pot to ajust the voltage or what i don't really understand how it works can you guys help me? and also would these pots work/

http://cgi.ebay.com/100-Ohm-1-Turn-...ryZ58164QQrdZ1QQssPageNameZWD1VQQcmdZViewItem

sorry for all of the questions i am full of them since my experience with electronics is limited

 

[dilmah]

ok i read through this entire thread

phew

all my problems were answered

thanks for everything


and a HUGE thanks to daedal - you've managed to educate someone with no prior knowledge in electronics.

i think im pretty pro now

 

[-Witch-Doct0r-]

lol 25 whole pages nice1 [smiley=thumbup.gif] there where like 17 pages when i first joined and that took me a while

 

[High_Octane]

Well I got the circuit breadboarded and its working great.
Thanks DDL
Now to try and make it as small as possible on a circuit board.