homemade driver

[stackingmont]

here's some pics of my homemade laser diode driver. i followed dd's schematic. before i hook up my precious new sony diode, i wanted some input from more experienced laser-ers. im using 2 10 ohm resistors in parallel, a 25 ohm rheostat, a 47uf 35 volt capacitor, and an LM317T voltage regulator. will this work for a sony 16x diode?

 

[stackingmont]

Re: will this circuit work?

heres another one of it out of its project box. its connected to 4 AAA's and a rocker switch.

 

[stackingmont]

Re: will this circuit work?

one of it inside its project box. man my camera sucks.

 

[chido]

Nice, but I think that you should put in a little bit more than 6v because otherwise your regulator is going to start dropping out pretty soon. Oh, and are you going to use a heatsink? :-?

 

[stackingmont]

i might just mount it on a small aluminum block i have for some reason. that will do the job of taking away some of the heat of the aixiz. what do u mean by my regulator will drop out?

 

[chido]

Well for what I know the circuit needs at least 6 volts to work, so if you provide it with 4 AAAs as soon as they start getting weak the LM317 won't have enough energy to provide the LD the current it needs.
Look at Gazoo's post here:
www(dot)laserpointerforums.com/forums/YaBB.pl?num=1181635652/450#450

Sorry, I can't post any links yet.

 

[Phazonx]

i might just mount it on a small aluminum block i have for some reason. that will do the job of taking away some of the heat of the aixiz. what do u mean by my regulator will drop out?

I'm pretty sure it means that it will start dropping the voltage below what you set it to. It will go from 3 volts and start going down.

I think it needs 5 volts to work good.

 

[Phazonx]

Well for what I know the circuit needs at least 6 volts to work, so if you provide it with 4 AAAs as soon as they start getting weak the LM317 won't have enough energy to provide the LD the current it needs.
Look at Gazoo's post here:  
www(dot)laserpointerforums.com/forums/YaBB.pl?num=1181635652/450#450

Sorry, I can't post any links yet.  

Yeah, that sucks it won't let you post a link. I think they do that so people don't register here to spam and put links to there porn sites.



But honestly, I don't get why they won't let you post a link to another section of laser pointer forums :-?

 

[chido]

I think it needs 5 volts to work good.

Phazonx it needs at least 6 volts to work. The LM317 takes 3 volts, if he had a diode in there it would take an extra .7v, and since he's using two 10 ohm resistors, that's 250mA going to the LD (assuming he's running it at that current since he could be running in less because of the rheostat) which would be 2.8v, he's providing the circuit with 6v (6v-3v-2.8v=.2v) so he's left with .2v. As soon as the batteries get below 5.8v the voltage going to the diode will drop as well as the current, that's why I think he should use 5 AAAs instead of 4 so that he powers the circuit with 7.2v

EDIT: Oh he is using a diode, so he has to use 5 AAAs if he wants to power it at 250mA.

 

[Gazoo]

Yup, you are 100% correct I think the best solution is to use six nimh batteries. Using 5 nimh or alkaline batteries can still cause problems. The nominal voltage of a nimh is 1.2 volts, so if you have 5 you have 6 volts. And we know how fast alkaline's sag. Using six will give a long run time too before the batteries need to be recharged.

 

[flogged]

[quote author=Phazonx link=1198950760/0#6 date=1199073406]
I think it needs 5 volts to work good.

Phazonx it needs at least 6 volts to work. The LM317 takes 3 volts, if he had a diode in there it would take an extra .7v, and since he's using two 10 ohm resistors, that's 250mA going to the LD (assuming he's running it at that current since he could be running in less because of the rheostat) which would be 2.8v, he's providing the circuit with 6v (6v-3v-2.8v=.2v) so he's left with .2v. As soon as the batteries get below 5.8v the voltage going to the diode will drop as well as the current, that's why I think he should use 5 AAAs instead of 4 so that he powers the circuit with 7.2v

EDIT: Oh he is using a diode, so he has to use 5 AAAs if he wants to power it at 250mA.[/quote]

Hmm, well I just built one using 4 AA NiMH batteries and it works fine with Daedal's circuit and Senkat diodes. Perhaps the voltage is on the low end but it's still enough to get the diode to lase. I adjusted mine to 225 mA and it's humming. Great little burner, was able to pop a balloon over 40 feet away with it. See my post in red lasers.

NiMH are preferable to alkalines (besides being rechargeable) in that they have no trouble supplying the needed current and their voltage does not sag under load nor until the end of their life - alkaline batteries voltage drops as they age and under load so the circuit may well see less voltage with alkalines than with NiMH.

 

[flogged]

here's some pics of my homemade laser diode driver. i followed dd's schematic. before i hook up my precious new sony diode, i wanted some input from more experienced laser-ers. im using 2 10 ohm resistors in parallel, a 25 ohm rheostat, a 47uf 35 volt capacitor, and an LM317T voltage regulator. will this work for a sony 16x diode?

I think it's good.. however I wonder if the orange wire going from the regulator should go between the diode and resistors and not as you have between the diode and cap.

 

[stackingmont]

[quote author=lasercricker link=1198950760/0#0 date=1198950755]here's some pics of my homemade laser diode driver. i followed dd's schematic. before i hook up my precious new sony diode, i wanted some input from more experienced laser-ers. im using 2 10 ohm resistors in parallel, a 25 ohm rheostat, a 47uf 35 volt capacitor, and an LM317T voltage regulator. will this work for a sony 16x diode?

I think it's good.. however I wonder if the orange wire going from the regulator should go between the diode and resistors and not as you have between the diode and cap.

[/quote]
why is that?

 

[stackingmont]

o and im using 4 rechargeable NiMH AAA's. so u guys are saying thats not enough to make the LD lase?

 

[chido]

Ok, first tell me at what current you'll be driving the LD at.

 

[flogged]

o and im using 4 rechargeable NiMH AAA's. so u guys are saying thats not enough to make the LD lase?

4 NiMH batteries worked for me, you should be good. If they don't try 4 alks...

And about the circuit.. I don't know enough to say. Just make certain the pot is turned nearly all the way down when you first power up the diode. I carefully metered the current going through the circuit when I first turned mine on (using a multimeter) and set mine to 225 mA (just short of 250 mA). and marked this as the 'max' position on the pot.

Good luck.