What kind of circuit is this? Photodiode scanning?

Discussion in 'General Electronics Chat' started by electronice123, Jan 16, 2009.

  1. electronice123

    Thread Starter Senior Member

    Oct 10, 2008
    Can anyone explain this circuit to me?

    The circuit has LED's and photodiodes and a gate with variable speed that passes between them to turn the photodiodes on and off.

    There is also a scanning circuit that scans the photodiode pulsing.
    From what I have read the scanning circuit scans until it detects logic of the photodiode circuit, once it detects the logic, then it starts scanning again from the start position.

    I also read that the circuit scanning time sycronizes to the photodiode logic and makes a given pulse shape, and that the circuit continues to increase pulse width as the scanning time increases when the photodiode logic signal moves further away from the start position, and that the pulse width decreases when the photodiode signal reverses direction .

    The explanation goes on to say that the circuit produces a variable controlled pulse shape in a continuous repetitive manner and it transmits that signal to an analog voltage circuit.

    I just want to find a circuit like this so I can get a better description of what it does and how it works???

    Can anyone give me any references or explain this circuit better?

  2. hgmjr

    Retired Moderator

    Jan 28, 2005
    Did you mean to include a link in your post?

  3. electronice123

    Thread Starter Senior Member

    Oct 10, 2008
    I don't have a link for it. I read it from a book.
  4. beenthere

    Retired Moderator

    Apr 20, 2004
    I have seen something like that with a string of emitters/detectors that were used to integrate the area of leaves. The leaf was carried through the array on a transparent belt at a constant speed.

    Then again, I may have missed the point of the OP's circuit.