why the circuit does not works fine

Discussion in 'The Projects Forum' started by salman_ali, May 16, 2011.

  1. salman_ali

    Thread Starter New Member

    May 16, 2011
    2
    0
    hello everyone[​IMG]
    hello every one....i have implemented the circuit above for several times but that does not give me the desired output. i want a variable duty cycle out of it from one of its output point Ov...but instead it give sine wave as an output.....i have tested it with 3 different types of loads...resistive(upto 1M ohm), capacitive(1uf upto 10000Uf) and inductive(0.47H/ 22mH)...but still does not working.....i have also changed the optocouplers for several times.......kindly help me immidiately
     
  2. Wendy

    Moderator

    Mar 24, 2008
    20,765
    2,536
    The diode voltage drop is around 1.2-1.4V. Your LED drop is likely to be a bit more, though not definately. IR LEDs start around 1.5V Vf, while red go up to 2.0-2.5, and the colors above that drop even more voltage.

    This is one possibility.
     
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