Ceilingwalker
New Member
Good day all. I'm trying to make an indicator light circuit for water tanks. What I'm trying to accomplish is: liquid tank temp should maintain 140-degrees F, if 10-degrees lower and LED turns on, if 10-degrees higher a different LED turns on. I'm using a TLC272 dual op-amp, a 1M and 10K pot, and a 100K 3-wire RTD. I've attached my diagram. I'm not getting the results I expected. I expected to set my high and low referrences with the two pots, then have the LED's turn-on and off with the change in temperature of the RTD. When I replace the RTD with a 100K pot, it does what I need. I thought the RTD was linear, could this be my problem? I have been trying lots of different scenario's and I can't get it to work. I thank you for taking the time to answer this.