> I am designing a reflow oven and decided to use a triac to adjust > the power of the heater of the oven. I'm thinking of using an MCU > (ATmega8) to control the triac. However I lack knowledge on how to > drive a triac with an MCU. It must be opto coupled, since the MCU > will be connected to a host computer, thus, can't flow. Been there, done that. http://www.delorie.com/house/furnace/ The optos were MOC3011's, the alternacs (like triacs, but can handle inductive loads too) were digikey Q2015L6-ND's. You'll need a pull-down pin to get enough current (10mA) or use a transistor or mosfet to boost the current. I think they make 5mA opto's too, though. http://www.delorie.com/house/furnace/board-stuffed.jpg The white DIP-6's are the optos, the TO-220's are the alternacs. There's a 39 ohm resistor between them that limits the onrush current through the opto.