Digitally controlling triac firing angle

Discussion in 'The Projects Forum' started by Konstabel, Feb 26, 2008.

  1. Konstabel

    Thread Starter Active Member

    Jan 31, 2008
    Does anybody have an idea how to control the firing angle of a triac using a uP?
  2. beenthere

    Retired Moderator

    Apr 20, 2004
    In theory, yes. The uP will be a somewhat bust animal tracking the variables to do good control. Since the AC line frequency is invariant, the uP can track firing angle with a zero crossing detector input to begin a timing cycle.

    After that, it is a matter of the desired application. For lighting control, firing the triac at the same phase angle during every cycle is adequate. If the triac conduction is intended to maintain a constant voltage through a rectifier to a load, then an additional input will be necessary to monitor the voltage and adjust the conduction period.

    For some additional material about using triacs, here is a link to out Ebook section that talks about triacs -