Finally finishing up a project I started a few months back. This is a peltier junction temperature well for calibrating meteorological sensors.
The Peltier junction is controlled via an Omega PID controller, and utilizes an h-bridge for switching polarity to the cooler. An RTD sensor provides temperature feedback to the PID. This allows the well to be heated or cooled for different testing levels. I turned the well out of Aluminum, with a 1.50″ ID, so that it will receive off-the-shelf aluminum inserts for different sensors. The inserts can be drilled out to match whatever unit you have under test. I’m also going to make one insert that allows for propylene glycol baths.
This first unit was a bit of a science experiment. I will be building 2 more of these as “final” products for work, and for those I’ll lay out a circuit board to handle all the electrical connections, so that each component can be plug-able.
This unit is capable of -10C to +50C under normal conditions. Right now it has a 3-stage Peltier thermoelectric junction. I’m going to add another 3-stage unit. -50C is my goal for adjusting the offset on temperature sensors. If anybody is interested in one of these, I can make you one!