Hello friends!
Zero Crossing detector as the name suggest detect the zero crossing of the power supply(sinusoidal).Its circuit will give high pulse when the sine wave of the power supply crosses 0 degree,180 degree,360 degree and so on at each n*180 degree.
WHY WE NEED THIS?
When I started working on the Ac fan speed control and the dimmer circuit,i found this ZCD at each place during my search.Earlier i was working with speed control of the Dc motor and it was easily taken place with the help of Pulse Width Modulation(PWM).Here are some circuits where ZCD is used-
In the above circuit,the whole circuit which is connected with the Pin DP2 is the Zero Crossing Detector.One can use the same circuit with the any of the microcontroller,Here The ZCD was designed with the Help Of H11AA1 IC.By the way friend if you want to dig deep on such interesting embedded circuit then you can look in to this book,it will help you alot-http://azon.ly/jkq0
ZCD sync or create coordination between the PWM and the Sinusoidal signal.As we know that the speed control is directly dependent upon the firing angle of the Triac(Firing Angle On the thyristor),as the firing angle is more the speed will be much slower if the firing angle is minimum the speed will be maximum,speed will be maximum at zero firing angle means at input supply.
Lets take an Example
here the firing angle is 4ms after the sine wave has crossed the zero,180 or 360,So how the micro controller will know when sine wave has crossed the zero,180,360 so that it can fire the Pulse after 4ms,So that is the task which is done by the ZCD it will hold the firing till it send a high pulse to the controller.It send high pulse only if the the sine wave crossed the at Zero,180,360 degree.
Zero Crossing Detector can be made with several ways but I found it most easy with H11AA1 as shown in above circuit.
Lets look at some other-
here is another one a bit complex-
I hope you liked my blog,Your suggestion is always welcomed.Send me the topic which you need me to explain.
Zero Crossing detector as the name suggest detect the zero crossing of the power supply(sinusoidal).Its circuit will give high pulse when the sine wave of the power supply crosses 0 degree,180 degree,360 degree and so on at each n*180 degree.
WHY WE NEED THIS?
When I started working on the Ac fan speed control and the dimmer circuit,i found this ZCD at each place during my search.Earlier i was working with speed control of the Dc motor and it was easily taken place with the help of Pulse Width Modulation(PWM).Here are some circuits where ZCD is used-
ZCD sync or create coordination between the PWM and the Sinusoidal signal.As we know that the speed control is directly dependent upon the firing angle of the Triac(Firing Angle On the thyristor),as the firing angle is more the speed will be much slower if the firing angle is minimum the speed will be maximum,speed will be maximum at zero firing angle means at input supply.
Lets take an Example
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| courtsey-Tahmid's blog |
Zero Crossing Detector can be made with several ways but I found it most easy with H11AA1 as shown in above circuit.
Lets look at some other-
here is another one a bit complex-
I hope you liked my blog,Your suggestion is always welcomed.Send me the topic which you need me to explain.
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