AC Power Control with Thyristor – Pulse Skipping using triac with PIC16F877A

Here’s the output waveform:

You can clearly see that out of every 5 complete cycles, the output consists of 3 complete cycles and 2 are missing – these are when the triac is off. Notice that the triac is fired 6 times in every 5 complete cycles – the triac is on for 6 half-cycles and off for the next 4 half-cycles.

Now, let’s look at a few other cases.

Here’s the output with 3 complete cycles on out of every 4 complete cycles: