Driving a Peltier element (here represented as motor to see direction change) for a wine refrigerator, allowing heating as well as cooling with an off state for the target temperature of 16-18°C. The OpAmps are LM393 types. The LEDs are here only for didactic and testing (easier than looking at relay contacts). There seems to be enough hysteresis in the working simulation to avoid continuous switching, would like to stay within 1°C = 1k range for the NTC.
If anyone comes with a better (read "easier") idea as well as the NTC setup at the front (actually NTC 10k with 13-15k range for 16-18°C range)
The top potmeter sets the target temp
