Ice Detector Design

[nosilverspoon]

I am looking at your old posts and wondering what final circuit you came up with? I have a similar need and could design something, but would have to go through all the testing etc that you have gone through. Are you willing to share?

 

[ADWSystems]

The final circuit was fairly simple. LM34 sensor into a MC34072 with 5x gain (resistor network is 4:1 ratio as non-inverting gain is 1+R1/R2). LM393 set for 40degF/60DegF. The threshold voltage is set by pot through voltage follower using the other half of the MC34072. I will work up a schematic when I have a chance.

The LM34 is mounted to a piece of strip perf board (opposed to pad per hole), that is 0.4" wide and 0.8" long. I covered the connection is liquid electrical tape and coated the IC with thermal paste. I placed this assembly in a piece of 1/2" copper tubing with a cap soldered to one end and the other end is just slipped on. The slip-on end has a hole drilled in for the cable to pass through. As this is installed within the dehumidifier coil, I cannot get a picture of it anymore.