A thermocouple generates a voltage as a result of the interaction of heat being applied to ma junction of dissimiliar metals. If you are measuring resistance, then you don't have a thermocouple. You probably have an RTD, ie...Resistive Thermal Device. Jim ----- Original Message ----- From: "Dr Skip" To: "Microcontroller discussion list - Public." Sent: Thursday, September 25, 2008 10:04 PM Subject: Re: [EE] creative fix? > Good idea. I'm no expert in thermocouples, and that's what the manuals say > it > is, but it's measured in ohms, not volts, and the resistance changes with > temp. > It seems to be fine per the test specs. > > Everything is clean, and reseating a few times didn't change anything, but > in > going to check the ripple (non present BTW) it came up nice and stable and > bright and now is working again. No visible solder flaws, so maybe it's > just > bad connector contact. It took a lot of re-insertions though. I'll use the > time > to come up with specs for the probe and driving the relays now. :) > > Thanks for the help. I'll probably make a 555 board just in case. ;) > > And as for just buying a new one - that's really not the EE spirit, is it > now? ;) > > > Thanks again. > Skip > > > > Richard Prosser wrote: >> Skip. >> >> Just because the thermocouple is producing a voltage, doesn't mean it >> isn't damaged in some way. Do you still get the error message if you >> short out the thermocouple?? >> >> I'd look initially at a simple relay control with adjustable duty >> cycle and an external thermometer of some type (eg a known >> thermocouple). >> You can then work out the on/off ratio to maintain a given >> temperature. The cycle time could be a minute or two so you wouldn't >> need anything too elaborate - a 555 timer should be able to be >> configured to do the job. >> >> This should give you a bit more time to come up with a more elegant >> solution, and allow you to work out the characteristics of the unknown >> thermocouple. >> >> >> Richard P >> >> >> 2008/9/26 Dr Skip : > -- > http://www.piclist.com PIC/SX FAQ & list archive > 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