Peter - take 4 x 1N1418 diodes and connect them in series. Also connect a 1k resistor in series with the whole lot and bung it onto a 5v supply. You will get a suprising linearity and repeatability of results not to mention the fact that you can measure a wide range of temperatures (I've tried over 300 degrees C and its still settled back to room temperature afterwards). Worth a go for 10c worth of components Dom ----- Original Message ----- From: "Peter McNulty" To: Sent: Sunday, December 01, 2002 4:39 AM Subject: [OT]: Temperature Sensors? Hi, What temperature sensors would you recommend for: -Fast Response Time (90% of actual temp) -Relatively Cheap (This is a school project, so nothing that costs $100) -EASY to program for using PIC16F877 - This is a must! Themistors are looking to be very difficult to program for, for a nice accuracy -Accuracy of sub +- 1degreeC I've looked at the LM335 solution, but the response time is very long compared to other things, and so is the maxim chip. I've also messed around with thermistors, just printing out an ADC value and they seem to vary the most, but they are hard to program for as they are non-linear, and they change over age. RTD's look good, but i can't get a definate price on these things yet, and they are linear with a fast response time. Thermocouples I haven't really thought about, though i don't know if they have thermocouples for the range of -50C to 100C with a nice accuracy, fast response time and easy programming. Are thermocouples linear? Are there any other solutions i haven't thought of? What are your opinions of solution i need? Thanks -Peter -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details. -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email listserv@mitvma.mit.edu with SET PICList DIGEST in the body