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Activating a circuit using a photocell

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  1. #1
    mtrails
    mtrails is offline

    Default Activating a circuit using a photocell

    Hi,

    I'm on the low scale of elcectronic engineering, and basic knowledge of basic circuitry, and have two scematics of circuits I would like to combine as one:

    Circuit 1

    A basic LED alternating flasher

    Circuit 2

    A photocell detector

    Objective: Use the photocell detector to activate the alternating LED circuit. When light is present, the alternating LED circuit is OFF. When light is diminished, the LED circuit is switched ON.

    The schematic of the photocell detector, uses 3 LED's as indicators. If possible, is there a controlled circuit that uses the voltage recieved of one of the LED's (signaling low light), that might be interfaced with a transistor to switch on the separate circuit?

  2. #2
    lord loh.
    lord loh. is offline
    Where are the schematics?

    If you are using a 555, you could use the output of the photo detector to hold the reset pin of the 555 low when light is present and high when light is not present... A transistor could work as an inverter.

    Whas this what you were asking?
    Bharath Bhushan Lohray.
    M.S. Electrical Engineering.

  3. #3
    akg
    akg is offline
    the immediate solution comes with the 12F PIC .. but if ur not interested with that u can do it with a comparator and 555(as blinker)

  4. #4
    mtrails
    mtrails is offline
    Quote Originally Posted by lord loh.
    Where are the schematics?

    If you are using a 555, you could use the output of the photo detector to hold the reset pin of the 555 low when light is present and high when light is not present... A transistor could work as an inverter.

    Whas this what you were asking?

    Yes.

    Here is the link to the schematics:

    Photocell Detector http://home.cogeco.ca/~rpaisley4/xComp555photo.html

    LED Flasher http://wild-bohemian.com/electronics/flasher.html

    Thanks

  5. #5
    akg
    akg is offline
    u connect the o/p of the photocell detector ckt (using 555 ) to pin 4 of led flasher (using 555) . the 555 requires a 'high' on pin 4 to oscillate which is provided by the photo-ckt during dark .

  6. #6
    mtrails
    mtrails is offline
    Great! Thank you for your responding to my inquiry.

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