At my local Maker Space, a few of us have been attempting to make our own beer. When someone found a load of brew kits reduced and bought the lot, I decided to have a go and wanted a temperature control system to keep it at just the right temperature for fermentation. Another member had used a heat bath to keep the fermentation bin warm. I wanted to build on this to control the temperature and log all the data to help improve my brewing.

I had a rummage through my parts bin and found the bits and pieces in the components list and ended up with the following circuit: