Auto DC iris control

Discussion in 'The Projects Forum' started by bluegreen, Aug 20, 2009.

  1. bluegreen

    Thread Starter Member

    Jul 22, 2009
    I have to analyse a circuit which involves opening and closing of the iris based on the light levels.I have no clue how the iris mechanism of the lens works.But basically opening and closing is acheived using a dc motor.

    Here are a few questions:
    1. How does one seperate the brightness information from the CVS.My circuit has a Low pass filter at the input side with a very high cutoff frequency (The CVS is fed to it).Dont really know what exactly it is seperating.

    2.This is followed by an op amp circuit to generate a voltge proportional
    to the output of the LPF.

    3. Ultimately after some more processing four signals are generated.
    These are fed to a 4 pin connector.
    The signals are labelled con+,con-,DR+ and DR-

    4. These signals drive a motor which accordingly opens or closes the iris
    to adjust the light entering.

    Can someone please explain how the motor controls the opening and closing of the iris.Please explain in detail.I chose not to post the entire circuit because it is pretty complicated and not really necessary to understand the working of the motor in acheiving the opening and closing
  2. beenthere

    Retired Moderator

    Apr 20, 2004
    Sorry to be ignorant, but what is the CVS? A Google search turns up a software app that tracks version information - probably not a light sensor.