Marc Nicholas wrote: > I've done close to that distance using Cat5 twisted > pair....interestingly enough, the device I was measuring the > temperature of was a large "in window" air conditioner -- lots of EMI! I'm curious -- why should there be lots of EMI? AIUI, these units tend to use induction motors exclusively, for both compressor and fan, which are fairly "clean" as far as EMI goes. Modern units probably use SSRs to turn the motors on and off, which would switch on at zero voltage and switch off at zero current, and this should also be fairly clean as far as EMI. -- Dave Tweed -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist