Could a solid-state-relais be used? Like one from the Sharp S201Sxx series? ----- Original Message ----- From: "David Challis" To: Sent: Saturday, November 29, 2003 8:18 PM Subject: Re: [PIC:] 220V Lamps with PIC- best switch Lurk-mode-off. Try using an pair of IGBTs instead of the TRIAC or dual SCRs. Start the half cycle (zero cross) with them turned ON. When the cycle get to the percentage of phase your require, turn the IGBTs off. IGBT can turn off in mid cycle, unlike TRIACs, which turn off at the zero cross (zero current through device). The IGBT have the added bonus of not requiring a hefty hash choke due to their relativiely slow turn off "tail current". Dave Challis -----Original Message----- From: pic microcontroller discussion list [mailto:PICLIST@MITVMA.MIT.EDU] On Behalf Of Jinx Sent: Saturday, November 29, 2003 4:10 AM To: PICLIST@MITVMA.MIT.EDU Subject: Re: [PIC:] 220V Lamps with PIC- best switch > I'm sure it is and I'm not going to try to picture what I'm not even > sure you're getting at, but to what effect ? I was trying to ascertain whether it's possible use a triac on the opposite side of the half-cycle than is traditional. Take for example a light dimmer. The triac is turned on between some degree and the next z-c. If the point at which the triac turned on was fairly high on the curve, say 90 degrees, this could cause undue stress on the filament because of inrush current and maybe lead to premature failure. My question was whether it was possible to have the triac conducting between 0 and 90 (z-c to midpoint), rather than 90 and 180 (midpoint to z-c) as above. The question was a poorly phrased attempt to find out if a triac can be forced off when it's conducting Your FET artwork pretty much answers it, cheers -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics