Re: Can we use TRIAC to turn ON/OFF AC devices like refrigirators ?
Using PICs and triacs here to switch industrial motors with no problem. I strongly advise using zero cross detecting MOC opto-triacs as Klaus suggested. A PIC can directly control the LED side and the burden of finding zero crossing is taken away from the software. For very big motors, I add a mechanical relay across the triac to short it out when the motor is running to reduce heat dissipation. My PIC controllers use a simple 'count up/ count down' routine, it turns the triac on straight away then counts 0.1 second intervals, after a count of 10 it closes the relay. When turning off, the relay opens straight away and the triac turns off when the count has gone down to zero. Doing it that way ensures the relay never switches more than a few volts so there is no contact arcing, the triac also runs cold because it only carries current for about a second at switch on and switch off.
Brian.