----- Original Message ----- From: "David W. Gulley" To: Sent: Thursday, January 23, 2003 12:46 PM Subject: [EE]Temperature Sensor > I am trying to find a temperature sensor with an accuracy of +/- 0.5 > degree F (or about 0.25 degree C). Most of the sensors I have tracked > down have an accuracy of 1 or 2 degrees C which is not appropriate for > this application. The range of temperature is from -40 F to 160 F (-40 C > to 72 C). > > Not having experience with the various sensors, I am not sure whether > the sensor accuracy is limited by device to device differences or > repeatability. If it is device to device difference, calibration of each > individual sensor over the range would be possible. > > I have not researched the subject fully as yet, but thought some of you > guys may have come across something like this... Anyone's experience > with accurate temperature sensing is greatly appreciated. > > Thanks, > David Gulley > > -- Hi there. I designed something similar with a range of -80 Deg C to 80 Deg C (wider ranges available) with an accuracy of about 0.2 Deg across the whole range using a 100R RTD. Units require no calibration, uses look up tables, software filter, 12bit A/D, order filtering, precision Vref and front end. The same pic16C74 also directly drive a multiplexed glass lcd. RTD is about $3 to $4 CDN and long term drift is low. I would suggest you request free samples. I released 2 plane MUX glass LCD code (3.5 digit & icons) to the list a while ago. If you want ideas for a cheap ($100 to $150) rampable thermal chamber (-30 to +30 Deg C), just ask. {slewrate} -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.