"Ian Field" wrote in message
...


"Arfa Daily" wrote in message
...

Arfa

Thanks. Do the TO18 style cases have standardised pinout? The laser is
pressed into a block of aluminium, I don't want to risk trying to pry it
out, and even if I did - any type number would end up obliterated.

Now that, I couldn't tell you, I'm afraid. Actual pin numbers or type of
the device tend not to be shown on schematics. Sometimes, the optical
block is shown just as a block, with no indication of what's in it at
all. About the only thing that I can say is that there is usually a
photodiode in the package as well as the laser diode(s). This is used as
part of the auto power control feedback loop. As to whether there are two
photodiodes in dual laser devices, I really don't know. If I get time,
I'll have a look on a few DVD schematics and see if any of them show
electrically what the optical block comprises.

Arfa


Had a proper look - it has got 4 pins.


I just had a look at a schematic set for a Sony home cinema unit. Although
it only shows the optical block *as* a block, all of the connections to it
are nicely labeled. There is one marked "DVD laser diode", one marked "CD
laser diode", and just one marked "PD", which is the feedback photodiode, so
it looks like just the one is used to monitor both laser diodes. So I would
guess that your four connections are the three as detailed, plus a common
ground.

Arfa