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hello Rohi,
you can use MOC30xx series optio isolators to drive your triac through microcontrollers. you can find lots of application circuits driving AC motors, AC lamps for light intensity control etc.
Please see following links for application circuits:
to make an AC dimmer you need to sense the phase of AC voltage and need to synchronize the firing of your triac with zero-crossing of AC waveform.
Hope this helps
The term PWM is ambiguous related to triac control, I think. It sometimes refers to full wave switching with variable duty cyle and several seconds period, which is the preferred method for quasi continuous heater control with solid state relays respectively triacs. As said, the on- and off-times have to be set as multiple of full waves.
The term "dimming" is primarly used for light control, which is limited to phase angle control. Lighting and small motor control (e.g. for hand tools and home appliances) are the exceptions where power quality regulations still allow phase angle control.
Hello asimlink & FVM.
Thanks for the reply.
I think we cac control the triac dimming by connecting the controller to the Opto coupler and adjusting the exact on & off time.
Triac gate and 1 st terminal is connected to Phase through opto coupler.
Help me if i am wrong
hello Rohi,
you can use MOC30xx series optio isolators to drive your triac through microcontrollers. you can find lots of application circuits driving AC motors, AC lamps for light intensity control etc.
Please see following links for application circuits:
to make an AC dimmer you need to sense the phase of AC voltage and need to synchronize the firing of your triac with zero-crossing of AC waveform.
Hope this helps
To sense phase of AC voltage you will need to use a zero-crossing detector circuit such as following: **broken link removed**
You can find lot many implementations of zero-crossing detector circuits if you search the term "zero crossing detector circuit"
You will need to connect the output of this ZCD circuit to interrupt pin of your microcontroller. In microcontroller firmware you can control the firing of Triac by
synchronizing with this zero crossing pulse. for a case of 50Hz you will get your cpu interrupted by every 10 mili seconds. Now if you turn on your triac imediately after zero crossing pulse is detected you will get 100% phase of AC. If you delay the firing of triac gate by lets say 5 mili seconds you will get 50% AC phase.
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