Welcome to Laser Pointer Forums - discuss green laser pointers, blue laser pointers, and all types of lasers

How to Register on LPF | LPF Donations

Build almost done!! 1 fast question.

grim3271

grim3271

0
Joined
Oct 25, 2012
Messages
48
Points
0
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..
 





grim3271 said:
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..
Click to expand...
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
 
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?
 
what kind of driver are you talking about? the LM317 based driver?
 
yes two 5 ohm resistors in parallel will give you 500mA of current
 
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.
 
yes i would take blords advice and maybe add a pot too 25ohm probably

:beer: Justin
 
Last edited:
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
 
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.
 
Last edited:
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.
 
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.. :P
 
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.
 
You must log in or register to reply here.


Back
Top