pwm outputs

Discussion in 'The Projects Forum' started by davejay, Mar 13, 2010.

  1. davejay

    Thread Starter New Member

    Mar 11, 2010
    1
    0
    hi have a k8055 interface board and i want to use the pwm output (5v) to control the speed of a 240v AC fan, i can't seem to find a way of converting one signal to the other
     
  2. retched

    AAC Fanatic!

    Dec 5, 2009
    5,201
    312
    PWM and AC motors don't go hand in hand.
     
  3. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    Google "variable frequency drive" to see how AC motors can be controlled in speed.
     
  4. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    Sorry, but you are indeed out of luck on that idea.
     
  5. Wendy

    Moderator

    Mar 24, 2008
    20,766
    2,536
    Try a SSR (Solid State Relay). The PWM frequency will have to be very low though, 1 to 10 Hz.
     
  6. aboamal

    Member

    May 29, 2008
    14
    0
    pwm outputs can be used to control DC motors but for AC you can use firing angle technique as following

    [​IMG]

    and the circuit will be like this

    [​IMG]

    and for 3phase motors variable frequency drive used for controlling speed
     
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