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Certainly! Below is a **step-by-step sample report** for your "Motor Controlled Fan System with LED Indicators" project. This includes all required sections with clear explanations and structure, suitable for first-year electrical engineering students. --- # **1. Title:** **Design and Implementation of a Motor Controlled Fan System with LED Status Indicators** --- # **2. Introduction:** This project aims to design and build a simple motor-controlled fan system that uses LED indicators to display the operational status of the fan. The system incorporates a 12V relay to control a 3V DC motor, which functions as a fan, and utilizes a transistor-based circuit for relay switching. A push button acts as the control switch, while two LEDs—green and red—indicate the ON and OFF states, respectively. This project introduces fundamental electrical engineering concepts such as relay operation, transistor switching, and LED indication. --- # **3. Explanation:** **a) Block Diagram:** ``` [12V Power] ----> [Relay] ----> [3V Motor (Fan)] | | [Transistor (BC547)] | | | [Push Button] [1N4007 Diode] | | [Red LED] [Green LED] ``` **b) Working Principle:** - **Power Supply:** The system uses a 12V power supply for the relay and a separate 3V supply for the fan motor. - **Relay:** The relay acts as a switch to control the 3V motor. When energized, it connects the 3V supply to the motor, turning it ON. - **Transistor (BC547):** The transistor works as an electronic switch. When the push button is pressed, the base of the transistor receives current through a current-limiting resistor, turning it ON and energizing the relay coil. - **Push Button:** The button controls whether the transistor and relay are activated. - **LED Indicators:** - **Green LED** lights up when the fan is ON (relay energized). - **Red LED** lights up when the fan is OFF (relay de-energized). - **Diode (1N4007):** Connected across the relay coil to protect the transistor from voltage spikes (back EMF) generated by the relay coil. - **Resistors:** Used to limit current to the LEDs and the transistor base. **c) Step-by-Step Operation:** 1. **OFF State (Initial):** - The push button is not pressed. - The transistor is OFF; thus, the relay is OFF. - The fan is OFF. - The red LED is ON, indicating the fan is OFF. 2. **ON State (Button Pressed):** - The push button is pressed. - Current flows to the transistor base, turning it ON. - The relay coil is energized, switching the relay contacts. - The 3V supply is connected to the motor, turning the fan ON. - The green LED lights up, indicating the fan is ON. - The red LED turns OFF. **d) Circuit Diagram:** *(Include a hand-drawn or software-generated circuit diagram here for your report.)* --- # **4. Applications:** - **Home Appliances:** Can be used in simple home automation systems to control fans or other small appliances with clear ON/OFF indicators. - **Educational Kits:** Ideal for learning basic principles of electronics, relay logic, and transistor switching. - **Industrial Control:** Used for status indication of small motors or machines. - **Prototyping:** Quick prototyping of control logic for various projects. --- # **5. Case Study:** **Scenario:** A classroom requires a small ventilation fan that can be easily controlled by students. The teacher wants a system where students can clearly see whether the fan is ON or OFF. This project is implemented in the classroom, allowing students to press a button to activate the fan, with immediate visual feedback via LEDs. This ensures safety (the status is always visible), and students learn about relay-based control circuits through practical experience. --- # **6. Conclusion:** This project successfully demonstrates the integration of basic electrical components to control a motor using a relay and transistor, with clear LED-based status indication. The system is simple, reliable, and provides an excellent foundation for understanding more complex control circuits. The use of a diode for back EMF protection and current-limiting resistors ensures safe and long-lasting circuit operation. --- # **7. References:** 1. Floyd, T.L., "Electronic Devices," 9th Edition, Pearson Education. 2. [Relay Basics - Electronics Tutorials](https://www.electronics-tutorials.ws/blog/relay.html) 3. [Transistor as a Switch - Electronics Tutorials](https://www.electronics-tutorials.ws/transistor/tran_4.html) 4. [BC547 Transistor Datasheet](https://www.electronics-tutorials.ws/transistor/tran_2.html) 5. [1N4007 Diode Datasheet](https://www.vishay.com/docs/88503/1n4001.pdf) --- ## **Final Answer Summary:** - The project involves a **fan controlled by a relay and a transistor switch**, with **LED indicators** for ON/OFF status. - **Push button** controls the transistor, which in turn activates the relay and the fan. - **Green LED** = Fan ON; **Red LED** = Fan OFF. - **Diode** protects the transistor from relay coil voltage spikes. - The project is ideal for beginners to understand the basics of **electrical switching, indication, and protection**. --- **Note:** Add your own circuit diagram and adjust references or explanations according to your teacher's requirements or your project implementation. If you need a sample circuit diagram, let me know!