Wireless control of wall switches : A module that controls your existing wall switch with an application

Sammanfattning: In this project a home-automation-solution is developed that wirelessly can control an existing wall switch with an application from a smart device. The purpose of the project is to develop a new solution that doesn’t require any electrical knowledge to mount the solution. Exiting solutions for controlling a switch require a module that is connected in series with the switch. The project will develop a module that can be mounted next to the selected wall switches to control them without electrical connection to the AC-voltage of the switch. Instead there is a servo that physically press the switch that is controlled. The servo motor is controlled wirelessly via Bluetooth Low Energy using an Android application, thus, a force is applied to the switch to turn on or off. A rechargeable lithium battery of 3.7 volts powers the whole module. Therefore, a "power-board" was developed that step up the voltage to 5 V. There are also components on the board that manage battery charging via microUSB. The Android application communicates via a Bluetooth Low Energy module that is mounted on a CPU board and has been developed and specifically manufactured to fit into the project. Both the power-board and processor-board is developed from own drawings and PCB layouts, and made with a manual etching method. The chassis has also been designed and manufactured with a 3D printer. The chassis holds all circuit boards, battery and a mount for the servo. The result is a working prototype that can be mounted on a switch and then operate the switch within the range of BLE. The prototype has a run time of each charging cycle of about 60 days under conditions that it is operated, on average, three times per day.