Light dimmer is a very handy device in many situations like various lighting effects starting with Christmas and ending with disco lights. You can find lots of light dimmer projects around internet, but this one has some handy features to consider.

It is a microcontroller based, so can be programmed to do various custom functions. Also it is featured with IR remote control capability. Additionally control commands can be sent  via RS232 interface. To make dimming more accurate there is a zero voltage crossing detection circuit. It enables to fire triacs precisely each time the line voltage crosses zero point. Once AVR requires low power (~20mA), there is a very simple power supply solution used without any transformers – only a energy storing capacitor, zener diode and resistor after then 5V stabilizer. So the whole design is quite lightweight.