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I have dissasembled a pick up head from a CD Rom. I can control the laser and but I also want to "read" the photodiode that senses the light reflected back. It is packaged in a clear plastic and has 8 pins. I can't see the entire ic but I can access 4 of its pins. Now I'm trying to determine what those pins do but I need more data about how they operate. I found a very similar device OPT101 that explains many of the external components of my photodiode. Beside the ic there are 2 capacitors,1 fixed resistor and one variable resistor.

enter image description here

Although the datasheet is different from my ic there are many similar traits.

Counting pins from left to right, here are my assumptions:

  • I think pin 1 is the actual output. From the datasheet , the feedback resistor(1M) is connected to output.

  • Pin 3 is ground.

  • either 2 or 4 is vcc(one of them I think is -V which I don't need)

I say pin 3 is ground because 2 and 4 are connected through a capacitor to this line.

To test which line is vcc I think there is a way: simply,if I connect the right line to 5v(or the lowest amount of voltage possible so that in case of wrong assumptions the damage will be minimum) the chip will work and I will be able to read the voltage from Output. If it's the wrong pin deduce the other one is vcc and hope the chip is still good.

What I want is more datasheets from similar products. If ,from your experience , you have seen anything like this one please write about it. And am I missing something(like the capacitors actually could be wired to vcc) that may help me find the pins ?

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  • \$\begingroup\$ First rule of adding photos: NO BLURRIES! If you can't get a sharp one, try again. If you really can't get a sharp one, despite your best efforts, do not use your "best" - just don't do it at all. \$\endgroup\$ – WhatRoughBeast Jul 11 '18 at 0:49
  • \$\begingroup\$ The photo is really at the limit .I've used FHD at limit of focus and with magnification. That flex cable is so small it's impossible to take a good picture. I'll try to draw a schematic. \$\endgroup\$ – sergiu reznicencu Jul 11 '18 at 4:45
  • \$\begingroup\$ Let me say again: First rule of adding photos: NO BLURRIES. Just because you can't do better does not make an unusable image usable. \$\endgroup\$ – WhatRoughBeast Jul 11 '18 at 12:29
  • \$\begingroup\$ So you are practically saying:why even bother? If I can't make it right,better don't do it at all.That's the thinking of a lazy person.Your comment would've been highly apreciated if it actualy contained any technical detail with regard to the question. \$\endgroup\$ – Reznicencu Bogdan Jul 11 '18 at 13:07

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