Build almost done!! 1 fast question.

[grim3271]

Hey. Everything is done. but the driver.. Am now putting the parts togeather. and i'd like to ask. for a laser diode out of a DVD burner..

What is the total OHM needed by resistors..

like..
2 10 ohm resistors?

2 5 ohm ones?

like.. i need 20 total ohm?

10 total? how much???

I 'm excited to run this diode..

 

[dentillozie]

Hey. Everything is done. but the driver.. Am now putting the parts togeather. and i'd like to ask. for a laser diode out of a DVD burner..

What is the total OHM needed by resistors..

like..
2 10 ohm resistors?

2 5 ohm ones?

like.. i need 20 total ohm?

10 total? how much???

I 'm excited to run this diode..

Depents on the current you want it to be driven, most dvd burner diodes are driven at 250mA. 1.25v / 0.25A = 5 ohm. The best way to get this is by taking 2 times a 10ohm resistor in parallel. This wil give you 5ohm.

Make sure you got a proper heatsink to cool your diode

Good luck

 

[grim3271]

My heat sink is a large half a KG aluminium heat sink. That monster will put the diode into the ice ages.. And thanks. i will activate the soldering iron again and solder 1 5 ohm resistor?

 

[foulmist]

what kind of driver are you talking about? the LM317 based driver?

 

[grim3271]

Yes. the lm317 one.

 

[foulmist]

yes two 5 ohm resistors in parallel will give you 500mA of current

 

[Blord]

500mA is way too high for an unknown red diode from a DVD-burner. I would set it much lower like 300mA.
Unless you are certain that it is a LPC-826 red diode.

 

[jwwilson23]

yes i would take blords advice and maybe add a pot too 25ohm probably

:beer: Justin

 

[grim3271]

Okay.. i now have the driver.. 1 lm317.. 100 ohm multi turn pot.. 2 5 ohm resistors all soldered togeather like this
http://www.rog8811.com/LM317 components01.jpg?0.35312663627278806

and i use 6 batteries for like.. 7.5 to 8.5 volts.. says the multi meter..

Anyway i put the positive only!! (i did not make the negative one yet maybe thats the problem)

and then measure what's coming out of the last resistor. and then i get..

about. the same.. But it kind of freezes not keeps jumping like how i directly connect them to the battery.

and the multi turn pot.. Does NO THING to voltage.. i turn it left/right still nothing.. maybe it does something with current..

but due that i did not connect the negative part yet.. I cannot measure the current

 

[Bionic-Badger]

Take a picture of your testing setup. Maybe there are some clues there.

 

[grim3271]

Pictures on thier way.

 

[grim3271]

Chip from the front
ImageShack® - Online Photo and Video Hosting

Chip from the back
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How i measure

ImageShack® - Online Photo and Video Hosting

Green to positive side of the batteries.
Yellow to the positive lead of the multi meter

Negative lead to the negative of the battery

ImageShack® - Online Photo and Video Hosting

And ofcourse the combined punch power of those

ImageShack® - Online Photo and Video Hosting

 

[jwwilson23]

if you have a power supply connected while measuring resistance doesnt it blow the fuse in your multimeter? looks like thats what happened but i will have to reread all posts again instead of skimming through.


EDIT-NM you are not doing R but i dont understand exactly what you are doing and why. are you trying to get the current? if so then you need a test load.. also the pot changes the current not voltage because you are changing the resistance w/ it

dont worry about the voltage the diode will take what it needs(w/ your driver)! and dont hook up the positive and try to get current(unless if you are doing this w/ a test load)! so it seems your driver is done i dont know. a clear pic of the setup closer would be a lot more helpful if you can. but you need a test load if you want to get your exact current. it should be right w/o one but dont count on it. it is not exactly needed b/c your diode is cheap but if you dont want to risk blowing it then i would use a test load.

:beer: Justin
also that is a breadboard correct? and if im a little unclear ask to clear it up im a bit tired its 1AM here.

 

[Bionic-Badger]

Actually, why don't you draw a diagram of the circuit, and how you're measuring it, and scan that. It's hard to tell what is going on in those blurry, dim photos.

 

[grim3271]

Well. I never tried to measure resistance lol.
Am just curious how much current will go to the diode.

Note.. i did not build the negative side of driver yet..

 

[tony1]

Blord is right a DVD red laser diode can't handle 500ma. You will fry it. I know cause I have fried one laser diode that way. Start with 300ma. Then try to tweak it slowly. If it turn bright suddenly turn it down immediately to save the Diode.