"New" sensor technology article

Discussion in 'Digital Cameras' started by Eric Miller, Oct 13, 2009.

  1. Eric Miller

    Eric Miller Guest

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  2. Eric Miller

    Charles Guest

    Thanks for posting.

    I remember years ago troubleshooting a very high frequency amplifier that
    would not "hold still." Turned out that the main RF transistor case was
    flawed and was admitting light which was affecting the bias and the gain and
    the noise. Knotty problem solved with a drop of black goop!

    Anyway, all semiconductor devices are light sensitive, some more than
    others.

    No way that memory chips are properly configured to be photo sensors. My
    guess is that the article was written by one with limited knowledge in this
    arena.
     
    Charles, Oct 13, 2009
    #2
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  3. We really are desperate for news in this field, aren't we.
    I recall making an imaging sensor from a 64kbit DRAM about 30 years ago!

    256x256 pixels, framing at TV rates! And that was following
    instructions from an article in a popular electronics magazine, though
    its so long ago I can't even recall which one it was, so I doubt I was
    alone!
     
    Kennedy McEwen, Oct 14, 2009
    #3
  4. Yup, it was a popular way of building small cheap cameras for robot
    vision. The best chips were the MIL-spec ceramic bodied chips with
    metal lids which could be carefully soldered off. Grey scales were
    obtained by repeatedly reading the memory cell while the light charge
    built up -- the longer the time to flip, the darker the cell. But
    today's young engineers are so hooked on novelty they refuse to read
    anything published before they were born :)
     
    Chris Malcolm, Oct 14, 2009
    #4
  5. Eric Miller

    Paul Furman Guest

    Digital film has arrived.

    :)

    Just drop the card in your old film camera and shoot. Remove the card to
    download the image. Wipe the dust off & shoot another... I'd guess full
    frame 35mm will be a couple grand or more but the rest is just that
    simple, plus some software. I like it.

    --
    Paul Furman
    www.edgehill.net
    www.baynatives.com

    all google groups messages filtered due to spam
     
    Paul Furman, Oct 14, 2009
    #5
  6. Eric Miller

    Bob Larter Guest

    Byte magazine published an article on how to do that, so that may be the
    one you're thinking of.
     
    Bob Larter, Oct 14, 2009
    #6
  7. Eric Miller

    Bob Larter Guest

    Yep, eg; a BC108. And I've even seen it done with an OC71, if anyone
    here is old enough to remember them. With them, you scraped the paint
    off the glass package.
     
    Bob Larter, Oct 14, 2009
    #7
  8. Eric Miller

    Walter Banks Guest

    Walter Banks, Oct 14, 2009
    #8
  9. Eric Miller

    Jeff R. Guest

    Or (nowadays), just use a teensy little LED. No sawing req'd.
     
    Jeff R., Oct 14, 2009
    #9
  10. Eric Miller

    Bob Larter Guest

    Pretty damn big, especially as OC71s are only light-sensitive at the
    side of the package, not at the top of it. Each RGB pixel would have to
    be about a square inch or so.
    I've never heard of diodes being affected by light, although I suppose
    that - at least in theory - it's possible that they are somewhat light
    sensitive.
     
    Bob Larter, Oct 15, 2009
    #10
  11. Eric Miller

    Bob Larter Guest

    I'm pretty sure that they used a 4164 DRAM with the lid removed, not an
    EPROM.
     
    Bob Larter, Oct 15, 2009
    #11
  12. Eric Miller

    whisky-dave Guest

    "David J Taylor"
    And there's photo diodes which are responsive to light by design.

    My very first exposure meter was a selenium cell IIRC. Which actually
    generated
    an electric current (didn't need a battery) to deflect a small meter needle
    on a scale.
    It had a cute little cream cover to protect the cell, I wish I still had it.
     
    whisky-dave, Oct 15, 2009
    #12
  13. Eric Miller

    whisky-dave Guest

    Probably as EPROMs are UV sensitive, well that's how you erase them anyway.
    it you don;t weant sunlight to erase them you cover up the window.
    They can take fro 5min to 30mins to erase using a small UV tube.
     
    whisky-dave, Oct 15, 2009
    #13
  14. Eric Miller

    Bob Larter Guest

    One day, I'll have to try measuring Vf on a 1N914 or 1N4148 while
    shining a light on them, just out of curiousity. That said, I've already
    noticed that LEDs made very good light sensors.
     
    Bob Larter, Oct 15, 2009
    #14
  15. Eric Miller

    Bob Larter Guest

    Yep, or you can put them on a sunny window-sill for a couple of days.
    (Although that's not a very reliable way of erasing them!)
     
    Bob Larter, Oct 15, 2009
    #15
  16. Eric Miller

    whisky-dave Guest

    Just did it, on a 1N4148 .
    office lighting 610mv : when shining a light CFL bulb at 10cm it rose
    to about 612mv,
    which could just be the DMM, but what I did notice using a hot air blower
    was that at about
    25C it was 580mv and at 70C about 500mv.
    I just had a thermometer next to the diode so not quite an accurate test
    but heat seems to affect it more than light.
     
    whisky-dave, Oct 15, 2009
    #16
  17. Eric Miller

    Bob Larter Guest

    Either way works.
     
    Bob Larter, Oct 16, 2009
    #17
  18. Eric Miller

    Bob Larter Guest

    Now, for that, you need to reverse-bias the diode. ;^)
    (And I suspect that a 1N4148 would probably work just as well.)
     
    Bob Larter, Oct 17, 2009
    #18
  19. Eric Miller

    John Turco Guest

    "Naked chips" -- how thoroughly shameful! No good can possibly come of
    this shocking exploitation of innocent silicon, I assure you.
    <edited>

    Oh, so, you're proud of yourself, Chris? You actually believe that
    mutilating tiny, defenseless electronic components, makes you some
    sort of hero?

    Heartless fiends abound, here in <
     
    John Turco, Oct 31, 2009
    #19
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