Red diode from DVD writer.

[qwas789]

Hi!

I extracted 2 laser diodes both i belive are 3.6-3.8mm from laptop DVD writer HP GSA-4084N (S05D), one is shaped like a round and other is like half round or 3/4 round.

Which one is red one? And does all red diodes have same pin layout?

 

[qwas789]

Bump.

 

[Bionic-Badger]

Take a picture of the diodes and the sled (mark where you extracted each diode).

 

[F4GRX]

When you measure the forward voltage of your diode with a diode meter, the red diode will show the highest forward voltage. There is no risk to destroy the diode, because the meter sends a rather weak current.

I did that yesterday. The IR diode had a Vf=1.3 volts while the red diode had a 1.4 volts Vf.

 

[qwas789]

I measured 1 diode 1.255 Vf and 1.355 other one. Bionic, i don't have sled anymore and i don't have any good camera that could get good enough picture of diodes. Is there anyway to get to know which pin is + and which is - with diode meter?

 

[F4GRX]

ok, so the diode with 1.355 Vf is most probably the red one

when you measured these values, the black probe was - and the red probe was +

you shall see a very, very faint dot of red light when you measure the red diode with the correct polarity. no danger to burn the remaining eye here.

 

[qwas789]

Ok, going to drive it at 250ma so i should be safe, need to find driver and aixiz module for 3.8mm. Any suggestion on that?

 

[F4GRX]

wow 250 mA? How did you decide that current? If you don't know the diode, you should use a variable current driver, starting at 0mA, and increase slowly the current until the lasing threshold; then increase the current even more carefully after that, while keeping an eye on an current meter

My current diode from a 18x DVD burner is lasing at 72 mA, and I'm happy with 100mA I'm sure I could go farther but I'm careful, I don't want to fry it

The bottom line here is that with and unspecified diode, you don't know Imax

 

[qwas789]

Thought that 250ma would be enough because LPC-826 runs on 300+ and this one would be just smaller compared to LPC-826. Gonna buy this one http://laserpointerforums.com/f67/ebay-adjustable-current-lm2596-power-supply-78568.html and going to experiment with it.

 

[Blord]

Thought that 250ma would be enough because LPC-826 runs on 300+ and this one would be just smaller compared to LPC-826. Gonna buy this one http://laserpointerforums.com/f67/ebay-adjustable-current-lm2596-power-supply-78568.html and going to experiment with it.

You need 400mA for +/- 250mW output for the LPC826 diode. They can be driven much higher but at expense of lower life time.

 

[AUS]

Yes make sure it's in a decent heat sink. I normally start around 100mA which is pretty safe for modern DVD burner diodes and work up from there. Keep watching the heat and how much current its drawing.

When you say one is half-round, is it a plastic or "flat" diode?

 

[qwas789]

AUS, it's more like half-round. Unfortunatly i broke 1 pin on my red when trying to solder it D: gotta order LPC-826 when i get free money.