Big part of our waste is organic that can be composted. Simplest way is to put everything in to pile and wait. In urban area you can face a bad smell problem that would annoy neighbors. The only way to avoid bad smell is proper timing in aerobic and anaerobic decomposition stages. So this project was born to keep track of compost pile temperature and take actions if needed. Aerobic processes are much faster and generate lots of heat.
Compost pile temperature monitor circuit consists of Atmega238 microcontroller which reads temperature values using metal can transistor. Voltage across transistor indicates temperature level. Reading occurs every 10 minutes as processes in compost are slow. By watching logs or simply following LED indicator it is possible to predict when aerobic processes are over and anaerobic take place what leads to bad smell. Simplest way to reset putrefaction in to aerobic again is to turn compost pile, so it could get oxygen.