I'll follow this thread closely. I've got an old idea to replace a mechanical relay controlling a 1200 watt load with a triac. Real similar appliaction. I kept running into problems with heat sinking (it has to squeeze into a thimble, of course, with no air circulation and no metal parts to bolt a hot triac onto...) At 1200 watts, 120V I've got a 10 amp load, with a 1.5 volt drop Triac that would be only 15 watts. Hmmm. I've also got some ideas about PID, when we get to that part. Keep talking, Jason! -----Original Message----- From: Harold M Hallikainen To: PICLIST@MITVMA.MIT.EDU Date: Friday, May 14, 1999 9:27 AM Subject: Re: 16A heater control? Triac? SCR? > I think a triac is about the most efficient way of handling the problem >(unless you want to go to an electromechanical relay). The voltage drop >across the triac would be about 1.5 volts, so multiply that by the >current to get dissipation in watts. Multiply the dissipation by your >heat sink's thermal resistance to ambient (degrees C/watt) to get >temperature rise above ambient. > For typical drive circuits for the triac, see the datasheet on the >MOC3020 or similar opto couplers. Also, for simplicity, you can just buy >an opto coupled solid state relay. The manufacturer of the SSR has >solved all the drive and snubber problems for you. You can drive the SSR >directly from a PIC. > >Harold > > > >On Fri, 14 May 1999 08:16:16 -0400 Jason Wolfson >writes: >>Today I'm trying to control a 1800W electric heater with a PIC. >>About 16A @ 110VAC, I was thinking of using a 25A Triac and >>optocoupler/driver. >>My question is how hot will the Triac get? is there a better way? >>cheaper? >>thanks >> >>Jason >>P.S. >>I've archived all the PID discussions for the next step of this >>project..... >> > >___________________________________________________________________ >You don't need to buy Internet access to use free Internet e-mail. >Get completely free e-mail from Juno at http://www.juno.com/getjuno.html >or call Juno at (800) 654-JUNO [654-5866]