Try the 3 to 4 diode in series trick (with resistor). They are suprisingly linear and I've managed to get 2 in series to hook up to a 10 bit a2d on the pic with suprisingly good results. I did the original testing for temperature swings on them using a mini blowtorch and they have survived (although they are a bit sooty at the moment). I almost dismissed the idea when I googled it and saw it mentioned but at 0.01 ukp per sensor (1N1418) it seemed worth a try. Just be careful about extreme temperature swings - you will crack the glass case if you transfer it straight from an ice bath to heated oil. If a diode drops 2.2mv (approx) for every degrees C - use 4 or 5 of them in series to give around a 10mV drop per degree. The other interesting thing I noticed was the tolerance between diodes was within 1% for the batch I had - made it much easier to mess about with other designs. Dom ----- Original Message ----- From: "Quentin" To: Sent: Sunday, December 01, 2002 6:34 PM Subject: Re: [OT]: Temperature Sensors? > > while we are talking about temp controllers! > > does anyone know of a simple thermocouple circuit using a pic or???? > > I would need the temp to go up to about 200c > > also are the adc features in the pics sensitive enough to > > sense the low output of the thermo couple with out amplification? > > No, the changes are small and non-linear. > Analogue Devices got a chip for thermocouples. > http://products.analog.com/products/info.asp?product=AD597 > -- > Quentin > qsc@iptech.co.za > www.iptech.co.za > > -- > http://www.piclist.com#nomail Going offline? Don't AutoReply us! > email listserv@mitvma.mit.edu with SET PICList DIGEST in the body > > > -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email listserv@mitvma.mit.edu with SET PICList DIGEST in the body