Paper Title
Design and Implementation of Microcontroller based Automatic Fan Speed Regulator using Mobile Phone

Past few years; home automation, remote control and monitoring systems have witnessed a rapid growth as a result of advancements in technology. As the world is becoming more technologically advanced, home and industrial automations are becoming more popular. Today, almost all the available Fans (standing and ceiling) are controlled manually by voltage regulators which have different stages of speed. This type of control is an uphill task for the physically challenged persons and the aged ones due to movement constraints. Sometimes; we are victims of electric shocks from our electric Fan when we try to regulate them, due to leakage currents from the electric switches/regulator. This paper presents the overall cost-effective “Microcontroller Based Automatic Fan Speed Regulator Using Mobile Phone”. The aim of the project is to develop a system which uses DTMF technology available in our mobile phones and Bluetooth module to remotely regulate the speed of a standing Fan. This project is a means of exposing another vital application of the mobile phone other than its primary purposes of making/receiving calls, sending messages, and browsing the internet. The designed project is restricted to the control of a standing Fan with three speed levels (speed 1, speed 2, and speed 3). The designed system has a Bluetooth interface. The range of the Bluetooth is 10 meters, thus; the user can be able to regulate the Fan speed within a distance of 10 meters. The system makes use of three (3) relays, representing the three speed levels of the Fan. Each relay is controlling a particular speed level. The relays are interfaced to the microcontroller via BC337 (NPN) transistors which acts as a buffer. When a key is pressed on the mobile phone, the tone of that particular key is coupled to the DTMF decoder via the Bluetooth module. The DTMF decoder chip (MT8870) decodes the frequency of the key, and generate the corresponding 4-bit code at the output (Q1- Q4); which are interfaced to the microcontroller for further processing and control. The microcontroller regulates the Fan speed by energizing or de-energizing the corresponding relay. We have discussed about hardware requirement, Software requirement, block diagram, flow chart, and the operation of the system. A satisfactory result based on the design specifications was achieved after construction. Therefore an indigenous low cost control system has been developed which can be used in real life application. Keyword- Dual Tone Multi- Frequency (DTMF), Global for System Mobile Communication (GSM), Bluetooth Module, Microcontroller, Relay, Seven Segment Display.