I built this device using a PID controller that I bought online. Since I am using this outside, I had to make it weather proof. The device is fully sealed and safe from rain water damage.
The way it works is by setting a temperature on the device. If the device senses that the temperature probe is below the desired temperature it triggers a relay to power a 110V outlet. I use a electric heating element that I plug into the 110V outlet. The outlet is triggered on and off until the desired temperature can be kept constant. I also installed an audio alarm that sounds when the temperature gets higher than my desired temperature.
|Here you can see all of the electronics and required wiring that went into the construction.|