“I have assembled Temperature Controlled Chamber Box for testing small electronic boards. In this tutorial I have shared my project including source files and link to Gerbers files to make the PCB.
I have used only cheap commonly available materials that where found in my stock. All electronic parts are DIP throughole for easy soldering.
The key of this project is controlling software that I still working on it. PIC controller uses PWM to control TEC current in cooling mode. You can see the graph of TEC current vs PWM dutycycle. Your setup maybe different.
To allow heating mode the circuit uses 2 high quality relays to reverse TEC polarity. Heating mode of the firmware currently works only as on/off mode that is not ideal for TEC lifetime, however since heating require less current and here in my location I not really need heating, I was less focused on heating mode programming.”