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
    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


    Mar 24, 2008
    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.