Arduino Sine Wave Dimmer

For a smooth signal we choose phase correct pwm at a frequency 31372 hz see previous post.

Arduino sine wave dimmer.

This circuit is only for incandescant bulbs. The figure 1 shows the mains sinusoidal wave with the frequency of 50hz sometimes 60hz. In the last article we learned how to generate sine wave pulse width modulation or spwm though arduino we are going to use the same arduino board to make the proposed simple pure sine wave inverter circuit the design is actually extremely straightforward as shown in the following figure. A real sine wave inverter s chopped wave form increase and decrease exponentially across x axis.

Dimmer is connected to arduino controllers via two digital pins. Second dim psm to control dim current. A zero cross detector circuit is required for ac dimming purposes. When the coding is finished one can verify and upload the code to the arduino board as explained in the project how to get started with the arduino.

The above chopped signal may not look like sine wave. To build a dimmer the zero crossing points the points where the wave changes its polarity are important. You just have to program the arduino board with the spwm code as explained in the. The pwm signal of an arduino is faster than the 50hz frequency so you will basically see the pwm signal modulated on the 50hz rectified sine wave making the effective voltage lower.

In our post for this we use pins 5 and 6 that means timer 0. The figure 2 demonstrates the schematic diagram of the whole circuit. This one channel ac dimmer made using the arduino uno board using a specified coding. Program developed by r girish.

But begin a simple design the chopping frequency stay constant and good enough to run most of electronic gadgets. The square wave can be observed using a cro which is connected to the pin number 8 and the sine wave can be. This is a circuit that tells the arduino or another micro controller when the sinus wave goes through zero and therefore gives a defined point on that sinus wave. To grab these points we have to use a zero crossing detector.

Opening the triac after a number of microseconds delay starting from the zero crossing therefore gives a predictable level of dimming. First zero to control the passing of phase null of ac which is used to initiate the interrupt signal. It is not for any inductive load as it is dc biased. This provides a stable signal at every zero level of the waveform and sends a signal to arduino to know about each zero level of a sine waveform.