The aim of the thesis is to develop and produce a small, affordable open-source circuit. This circuit consists of a temperature and humidity sensor. It can switch a light on and off. It may be linked to the smart home system using wireless technologies. In this way it is possible to manage and inspect values of sensors. It is based on Open Source technologies and platforms. The central system is based on the Raspberry Pi and Arduino platform with open-source software. It contains mechanisms for connecting with the circuit, and thus the management of this circuit. Review of data and management of the node are possible via the web interface and smart phone. The developed software code and scheme are published and freely accessible on the web.