Triac control of AC lamp

Discussion in 'The Projects Forum' started by ashucircuits, Dec 6, 2015.

  1. ashucircuits

    Thread Starter New Member

    Dec 6, 2015
    4
    0
    Hi all i am a pure newbe to Triacs, i want to make a lamp dimmer, switch using arduino.

    but first of all i am testing the parts saperately, i made the following schematic in Proteus,
    [​IMG]
    but as you can see the lamp is automatically glowing even if nothing is connected at input (1, 2) of MOC3021 ----- it is strange ?

    and there are no errors
    [​IMG]
    if it automatically glow how can i plan to control it by a pulse etc at input of MOC3021?

    pls tell me where i am wrong so that i can do successful simulation and then order the components and make the hardware

    thanks in advance
     
  2. JohnInTX

    Moderator

    Jun 26, 2012
    2,345
    1,025
    Try a resistor 33K-68Kfrom the gate of the triac to the lower main terminal (the one not connected to the lamp).
    Also, you might need a small capacitor in parallel with that resistor.
     
  3. Dodgydave

    Distinguished Member

    Jun 22, 2012
    4,979
    744
    You need to use a zero crossing opto like moc3041, or Il410, also you need to detect the zero crossing for your micro, to sync the pulses.
     
  4. MaxHeadRoom

    Expert

    Jul 18, 2013
    10,526
    2,369
    Look up the Fairchild App note AN-3006, it shows phase control from a device other than a pot.
    Max.
     
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