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Figuring out the pinout of a Class 1 laser salvaged from a DVD drive

treacheroustoast

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I'm working on salvaging a class 1 laser from a DVD/CD RW drive taken from a computer, and the part I'm a little worried about is destroying the diode if I wire it up wrong. Should I look for schematics online? Or is there a standard pinout for small laser diodes?
Thanks
 



Immo1282

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Google and the Search bar on this forum are your friends. This has been done loads before, all the info you'll need is up here somewhere :)
 

diachi

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The laser from a DVD/CD RW drive is not class 1. The whole DVD/CD drive itself is class 1 when unopened, but the diode in side is class 3B.

This seems to be the most common pinout for 5.6mm 3 pin diodes from DVD writers.



Keep in mind one of the diodes is an IR diode at around 780nm, which is almost invisible.

Not sure why anyone bothers tearing DVD drives apart anymore, you can buy the diodes new for <$10.
 

Cyparagon

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They're somewhat tolerant to reverse polarity. They are diodes after all. Matching best-guesses from google is risky for unknown diodes.

Here's my method that has near-zero chance of damaging things, provided you have a bench power supply and know how to use it.
I bring up the voltage slowly with a current-limit near zero and watch the output:
1) If there is noticeable current draw (say, above 10mA) at or below 0.7V, that pinout/polarity is wrong. Try another.
2) If there is no light at all coming from the device at 1.5V, that pinout/polarity is wrong. Try another.
3) If there is a very dim light emitted around 1.5V, that pinout is most likely correct. Continue increasing current.
4) If the light remains very dim at 50mA or so, the diode is either dead, or you have found the IR laser diode in the case. If you were looking for red and not IR, try another pinout.
 

Nexgen

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I harvested plenty of them. They have different pin out for each. Some are case negative some positive. But none of them were case neutral.
 

Benm

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As far is i can remember using diodes from dvd writers they have all been case-negative or case-neutral, but never case-positive as is common in 808 pump diodes.

There is a bit of a catch here though: they usually have 3 pins, often with the center one connected to the case. The other two you need to figure out: one of them will power the laser diode (with a positive voltage on in with respect to the case), the other one can be a photodiode feedback, or simply not connected at all.

And yeah, make sure you have the correct diode: the one for dvd's is brightly visible red, the one for CD's is almost infrared and barely visible even at full power output. It is, however, very dangerous to look into the focussed output of such diodes!
 




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