John Brohan wrote: > Hello > > I have a device which has a PT-100 temperature sensor. The probe of > this is too thick for what I need. I want to measure the temperature > of liquid in a test tube while I'm adding some reagent. It seems that > the PT-100 is a device with some size to it, and is just too bulky to > fit in the test tube along with a stir bar. I'd prefer to use a > thermocouple. > > Does anyone know of a way to transform the signals from a > thermocouple to mimic the a PT100. The Variomag reaction block I'm > using has a very convenient way to handle this temperature (and I've > already written the interface to it).
Electrically you could do it by using the channel of a FET to simulate the PT100 and feeding the gate from the thermocouple voltage. With lots of extra bits around to tweak gains and offsets. It would probably be a pain in the arse to get right and make stable. But given it's possible there may be a module out there somewhere that does it, sold as an adapter or convertor, although I've never come across one. It would be a lot of work to simulate a 4 wire PT100 probe in software using a DAQ card. I've had custom thermometry probes made up by http://www.tc.co.uk/ in the past- they do a range including PT100 and may be able to help. Can't you use the temperature probe as your stirring stick? Or is a machine wiggling it? -- Dr. Craig Graham, Software Engineer Advanced Analysis and Integration Limited, UK. http://www.aail.co.uk/
