How would one of those thermal couples that is used in gas heaters and water heaters to keep the pilot light on and power the thermostat work as a sensing device? Bill ----- Original Message ----- From: "Mark Scoville" To: Sent: Monday, October 18, 2004 9:31 AM Subject: RE: [EE]: Temperature sensor for my oven? > > -----Original Message----- > > From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu]On Behalf > > Of Philip Stortz > > Sent: Sunday, October 17, 2004 3:05 AM > > To: Microcontroller discussion list - Public. > > Subject: Re: [EE]: Temperature sensor for my oven? > > > > > > i've seen lower prices for the very basic bare junction type for > > multimeters. also check omega.com, lots of thermocouples and wire (and > > you can make your' own thermocouple from the wire by welding it together > > with a capacitor discharge, ideally but not necessarily in argon > > depending on your accuracy needs, or even soldering though it's not > > ideal). for a single device, ebay is of course often helpful. the nice > > Yes, Omega has lots of stuff. Good tutorial section on thermocouples in > their catalog too. > > When desperate I have in a pinch twisted the thermocouple wires together > tightly using a bench vise and pliers - no welding or soldering. I've never > checked to see how *Bad* this is. I know it's not ideal, but when you don't > have anything else it's better than nothing. > > > thing about thermocouples is that they are nearly linear, an rtd is a > > terribly non-linear thing. then again thermocouples have their down > > side as well, but i like them for reasonably high temperatures. an rtd > > (or thermistor) is best for control around a single point, then you can > > set up a bridge etc. with the appropriate value resistors, otherwise you > > need that pesky lookup table which adds code and makes a pure analog > > solution difficult. i believe national and/or ti also have chips > > specifically for interfacing with thermocouples. > > FWIW, Linear Technology makes thermocouple interface chips too (We use the > LTKA00 & LT1025 chipset for J type applications) > > -Mark > > > > > _______________________________________________ > http://www.piclist.com > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist _______________________________________________ http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist