Duty cycle question ?

Discussion in 'General Electronics Chat' started by curry87, Feb 22, 2011.

  1. curry87

    Thread Starter Member

    May 30, 2010
    How does changing the duty cycle of a pwm generator change the voltage it outputs and are all pwm generators like this ?

    Whats the difference between a square wave generator and pwm generator ?
  2. GetDeviceInfo

    Senior Member

    Jun 7, 2009
    Let's flush out the terms first. A pulse width modulator isn't termed a 'generator', rather, it is more apt to be described by it's function, that of a modulator.

    If I give you 10 dollars a month, you have a certain cash flow. If I give you 80 dollars a month, you have a larger cash flow. So is it with the modulator. It varies the duty cycle (monthly cash payments) to suite the reference.

    Which then comes to difference between the generator and the modulator. Other than the fact that the modulator's function is that of varying duty cycle, one might venture to say that the generator is a fixed source, whilst the modulator utilizes feedback.
  3. Audioguru

    New Member

    Dec 20, 2007
    PWM operates at a fairly high frequency. The voltage quickly switches high and low but the average voltage is determinrd by the duty cycle.

    A square wave is also high and low but the duty cycle is exactly 50% so the average voltage is exactly 50% of the peak square wave voltage.
    curry87 likes this.