Convert Square Wave to Direct Current.

Discussion in 'The Projects Forum' started by NM2008, Feb 9, 2008.

  1. NM2008

    Thread Starter Senior Member

    Feb 9, 2008
    135
    0
    Hi,
    I am working on a radio controlled project, but am having difficulty with one thing. I want to run a relay off a servo output, but as the output, (connections to motor) is in the form of a square wave, I cannot have this. The relay obviously switches on/off to the square wave, whereas I cannot have this happing.
    Is there some form of circuit which I can build to rectifiy the square wave output to DC.
    Or is there an alternative way of running a relay from a servo output?

    Thanks for your help.
     
  2. Audioguru

    New Member

    Dec 20, 2007
    9,411
    896
    The square-wave fed to an RC servo is continuous. The width of the pulses is changed to move the servo or speed controller. So if you rectify the pulses then the relay will vibrate with a fairly low average voltage to a higher but still pretty low average voltage.

    You need a circuit that will decode the width of the pulses.
     
  3. NM2008

    Thread Starter Senior Member

    Feb 9, 2008
    135
    0
    Thanks for info, but would you know the name of the circuit I would need to look for?
    THANKS
     
  4. Audioguru

    New Member

    Dec 20, 2007
    9,411
    896
    I couldn't find an on-off circuit for Radio control.
    A pulse occurs about every 20ms. Its width is determined by the movement of the joystick. Minimum pulse width is 1ms and maximum pulse width is 2ms so you need a circuit to give a high when the pulse width is more than 1.5ms and give a low when it is less than 1.5ms.
     
  5. NM2008

    Thread Starter Senior Member

    Feb 9, 2008
    135
    0
    I will look into these,
    Thanks for the help!
     
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