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  1. #1
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    Triac: 60 Watt bulb flickering

    Hello everyone,
    I am using BT136 triac, MOC3021 optocoupler, and AT89C2051 µC and AN33 with rectifier and a step down transformer for zero crossing detection.
    The circuit is availabe in multiple website for the system.
    What I am doing here is, with AN33 I am detecting zero crossing and firing gate trigger to triac via MOC3021. Here the Triac input voltage is 230 volts, 50Hz. According to the concept, after rectification the the pulse will detected at 100 Hz (Zero crossing), i.e., 10 milisecond. So, I am taking a delay 2 at milisecond and firing a gate trigger pulse of width 60 microsecond. I have varies the delay time of triggering from 2 milisecond to 8 milisecond, at 2 ms, bulb is perfectly glowing but on incresing the delay, the intensity is not decresing but flickering. I want to dimm the bulb.
    Can you tell me the possible mistakes I am doing. I want to dim the bulb.

    Thank you.
    Shahrukh.

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  2. #2
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    Re: Triac: 60 Watt bulb flickering

    Hi,

    I guess there´s something wrong with your "delay".

    Use a scope to show the zerocross (as trigger) and the gate signal.
    Use a digital scope with "one shot" feature and show 2-4 fullwaves on the screen.

    Most probably the problem lies in your circuit / software / mains voltage ...
    Thus we need to see
    * your circuit (photo)
    * your software
    * your scope pictures

    Klaus
    Please don´t contact me via PM, because there is no time to respond to them. No friend requests. Thank you.



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  3. #3
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    Re: Triac: 60 Watt bulb flickering

    Can you tell me the possible mistakes I am doing. I want to dim the bulb.
    Something wrong with your zero crossing OR /AND triggering.

    That is all I can say with the info you provide.



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  4. #4
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    Re: Triac: 60 Watt bulb flickering

    Are you sure you are triggering the TRIAC once evry 10ms and not every 20ms...because the latter will cause flicker...also, i successive 10ms half sines, if you dont trigger in the same part of the sine, then it will look like flcker.



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