Hi John, Thermocouples are very robust, and have a very wide operating range. However they require extremely accurate voltage measurements to get to sub degree temperature accuracy. On top of that they require a local temperature sensor to measure the 'reference' temperature (Or an actual Icepoint bath). Once you have those that a lookup table or up to 14th or so order polynomials (Depending on thermocouple, and range) is required to convert the 'reference temperature' and millivolt reading to the temperature measured. Look at some of the NIST copies of the ITS-90 thermocouple tables and coefficients: https://srdata.nist.gov/its90/download/download.html https://srdata.nist.gov/its90/download/allcoeff.tab Overall, a lot of things going on there with errors that all stack up (including silly things like not enough range in floating point number routines for polynomial calculations). Don't get me wrong, they make great sensors. Probably not the right sensor for a small home brew board. IC Temp sensors, thermistors, or RTD's may all be reasonable options here. IC Temp sensors for simplicity, RTD's for accuracy, and thermistors (except where they are in a loop, holding the temp constant) for cost. Dan On 4/5/2018 12:00 PM, time-nuts-request@febo.com wrote: > Message: 11 > Date: Thu, 5 Apr 2018 09:44:48 -0500 > From: John Green<wpxs472@gmail.com> > To:time-nuts@febo.com > Subject: Re: [time-nuts] Environmental sensor recommendations. > Message-ID: > <CAGRb8tLmGXhOWOqSgxpG2c2xE8sKXnqk1y9_cHkmjwMiKEc4tg@mail.gmail.com> > Content-Type: text/plain; charset="UTF-8" > > Why has no one mentioned thermocouples? > I had some experience with thermistors a few years back designing thermal > attenuators and equalizers for CATV. NTC thermistors can have a large > change of resistance for a unit change in temperature. They aren't linear, > but there are formulas for computing resistance vs temp. PTC thermistors > have a much smaller change per unit change in temp., but are much more > linear. And, they are susceptible to self heating, which makes things > interesting. If I remember correctly, in my research something called an > RTD was supposed to be the king when it came to accuracy and repeatability. > As someone else has stated, the IC devices are supposed to be quite good, > but you have to interface with them.