DIY Homemade laser diode driver

[Viracocha]

The pot will only drop the current to a minimum, not completely off, so there could still be enough current passing to allow the led to stay lit.

Also try getting a 1 ohm resistor in series and checking the voltage across that, that will tell you the current passing through the circuit. The circuit is a current limiter (not voltage) so testing with a proper load like the diode system would be better then using an led.

My only other advice is to check the circuit and make sure it matches the diagram and check that you don't have the adjust and output pins the wrong way around.

 

[kneegrowplease]

ok, so I'm headed to radio shack for some more IN4001 diodes and a one ohm resistor and test it with a load.




P.S. My name was not meant to offend.

 

[kneegrowplease]

ok, with a test load i get between 42 and 182 milivolts and a 1.25 v reference. too bad I turned my LD into a LED somewhere along the way.I had a terrible time trying to install the LD into the 5.6 to 9mm adapter from meredith. What the hell, any hints? guess TheMonk is gonna get $20.00 from me, I NEED a diode.

 

[jonrobertd]

Ok so not reading thru all 50 (after first 5 and seing all these different things used here and there) something pages I have built this exactly as shown on the protoboard on page 1, except used the 25 ohm rheostat suggested from RS. Now is there anything to change to power a 22x LG diode. Sorry for being so noobish and not reading it all but kids come first.

Also have a 7.4v 450mah lipo battery to use but fully charged it it more at 8.2v and a 4x AA holder to use, which is best?
Thanks for all the prototyping this and making it simple for us. Am still confused though, LOL.

 

[adgmeijin]

Guys do you have estimated safest value of a resistor when you put it in parallel with capacitor? :-/, is it the parallel resistor lessen the needed current of LD from the driver? or it was only used to discharge the capacitor? just need simple guide for this one, cuz ive been using DDL Driver since i build my first RED laser, but never been using this good idea on using resistor for safer outcome.

 

[Nyla]

I ran into this question:

Why is it that the two of the pins on the pot, when used as a rheostat, are connected? What difference does it make and more importantly WHY does it make this difference? Like here:

If you don't connect pin #1 to the pot, but only connect #3 and #2, what's different and why?

 

[lasersbee]

If the center pin #2 (which is a mechanical wiper) would bounce and break contact..
the resistance value would go to infinity... with the center pin connected as shown,
the resistance can't go higher than 100 Ohms.

The center pin #2 wiper can also sometimes go past the maximum resistance and
land on a non conductive part of the pot and again creates the open circuit problem
if not connected as show.

 

[jonrobertd]

Ok so after reading it all I got most questions answered so I figured I'D post results:

all were taken with 7.4v lipo

1 ohm 712ma
3.2o 217ma
4.4o 157ma
5o 136ma
10o 73ma

With the 4.4o I am getting 1.7 to 2.14 volts on an IR diode.

 

[jonrobertd]

just didn't want this to get lost because I learned sooo much

 

[D.S.Darkness]

plzzzz, correct me if im wrong, but using the equation to find the resistance needed in ohms with the ma you want to run ( 1.25/ mA you want = ohm resistance you need) and the equation for resistors in parallel( R final = 1/( 1/r1 + 1/r2 + etc)). i would only need 1 ten ohm resistor in the DIY driver by Daedal, to power an 803t BR diode at 130mA?


-- srry if this seems like an abused question, i just want to get this clear, i ordered an 803t and i dont want to burn it up on accident. im trying to limit my driver to ONLY go upto 130mA max to limit the chance of burning out the diode.

-- One more question, will the 803t be able to burn anything at 130mA? i would think so, but being my first laser build.


-- SRRY but this just popped in my head, as long as i DONT touch any contacts together, would a cold heat soldering iron be fine for soldering onto the diode( to limit the heat into it for fear of cooking it )

 

[D.S.Darkness]

:-/ srry just need answer seems like no one is postin to much, which is odd since there are over 100 user on at any one time lol.

 

[rog8811]

I dont know, I go on holiday and questions are left unanswered tsk

plzzzz, correct me if im wrong, but using the equation to find the resistance needed in ohms with the ma you want to run ( 1.25/ mA you want = ohm resistance you need) and the equation for resistors in parallel( R final = 1/( 1/r1 + 1/r2 + etc)). i would only need 1 ten ohm resistor in the DIY driver by Daedal, to power an 803t BR diode at 130mA?

Looks about right to me, use a test load of 6 1n4001 diodes and a 1 ohm resistor to be sure before attaching your LD though.


-- srry if this seems like an abused question, i just want to get this clear, i ordered an 803t and i dont want to burn it up on accident. im trying to limit my driver to ONLY go upto 130mA max to limit the chance of burning out the diode.

-- One more question, will the 803t be able to burn anything at 130mA? i would think so, but being my first laser build.
My ones will light matches and burn skin @ 110mv


-- SRRY but this just popped in my head, as long as i DONT touch any contacts together, would a cold heat soldering iron be fine for soldering onto the diode( to limit the heat into it for fear of cooking it )

I am not sure what a cold heat soldering iron is, I always use traditional soldering methods, soldering has never killed an LD of mine....only stupidity has....

Regards rog8811

 

[jonrobertd]

Cold heat soldering?  Do you mean one of those battery powered  (this http://www.radioshack.com/product/index.jsp?productId=2062746 )soldering irons that don't get hot untill you touch metal. They get hot. I tried to solder LEDs with this and it melted the LED and not the solder, they don't work well for heat sensitive parts. I would not try it personally.

 

[ColdStl]

I finally joined LPF and have been reading (for many hours/days) about building this driver. My ?..If the pot were to be left out of the configuration, does the resistor lead that originally hooked up to the pot need to be hooked up to the LM317? Or does it connect to the silicon diode?
I apologize if I have missed the post on this subject.

edit:Nevermind... I found it.

 

[redelman]

There is more then one diagram, which one do I follow for the SLD1239JL-54 16x DVD burning laser? Or for the universal one on the very top of the first page, would setting the potentiometer to too little resistance on it screw up an SLD1239JL-54 16x DVD burning laser? If so what should I look for on my multimeter before attaching an SLD1239JL-54 16x DVD burning laser when adjusting the potentiometer? If not, can I adjust it to minimum resistance without damaging a SLD1239JL-54. Do I use 6v for an SLD1239JL-54. Sorry for asking so many questions

 

[redelman]

Also another thing about this picture, is the 1n4001 diode connected to the ground? Also is the white wire connected to the right side of the potentiometer connecting to hole 23, 5 or is it soldered to the middle of the potentiometer? Also if the black wire is ground why are there two connectors. Also which side of the regulators are in out and adjacent? This is why I prefer schematics over photos.