IR Beam Break detector Circuit

Discussion in 'General Electronics Chat' started by smsarmad, Aug 2, 2010.

  1. smsarmad

    Thread Starter New Member

    Jul 30, 2010
    6
    0
    Can somebody please explain the working of circuit components in the following circuit!


    [​IMG]
     
  2. JDT

    Well-Known Member

    Feb 12, 2009
    658
    85
    Well, basically, the TX part produces a modulated I.R. light. This means that it switches on and off at a known rate.

    The RX (receiver) part uses the 741 as an amplifier. The first capacitor (103) blocks any DC caused by ambient light, therefore responding only to the modulated beam.

    The amplified signal is rectified by the 4148 diodes and switches on the transistor C945 energising the relay. The 2u2 capacitor on the output of the rectifier ensures that the signal has to be continuously present for a short time before the relay switches. It is, in fact, a filter.
     
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  3. smsarmad

    Thread Starter New Member

    Jul 30, 2010
    6
    0
    Thanks for explaining its working! Can you please explain the transmitter's working as well! I couldn't get how is this IC 4093 (4 x 2-input NAND gates) is used to produce IR beam at a continuous rate.
     
  4. tom66

    Senior Member

    May 9, 2009
    2,613
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  5. zahidkjatoi

    New Member

    Apr 19, 2009
    3
    0
    Can anybody please explain the exact working of transmitter of above circuit.
    plzzzz
     
  6. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    Follow the link in post #4.
     
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