E&TC / ECE · Solar and power electronics · Final year project
Auto Light/Water Saving
A system that switches lights and taps based on whether people are present. IR sensors at the door count people entering and leaving, and when the count reaches zero the lights and water supply are switched off automatically.
What is the Auto Light/Water Saving project?
A system that switches lights and taps based on whether people are present. IR sensors at the door count people entering and leaving, and when the count reaches zero the lights and water supply are switched off automatically.
Key facts
- Type
- Final year project · Intermediate
- Suitable for
- Diploma capstone and B.E / B.Tech final year
- Build time
- 4 to 6 weeks
- Estimated component cost
- ₹2,100 – ₹3,100
- Guidance from
- ₹9,999 (Hardware / IoT Final Year)
How the Auto Light/Water Saving works
- 12 V power adapter / step-down transformer supplies the circuit; a regulator gives the controller and sensors a steady 5 V.
- The IR obstacle sensor module detects an object or line in front of it by reflected infrared light.
- The Arduino Uno R3 reads the inputs, runs the decision logic written in C/C++ and drives the outputs.
- The Relay module switches mains or high-current loads such as lamps, pumps and fans from a low-voltage signal.
- The LEDs indicate status.
Block diagram
Inputs
IR obstacle sensor moduleController
Arduino Uno R3Outputs
Relay moduleLEDsComponents list and cost
Typical prices from Indian online stores and electronics markets (Lamington Road, Budhwar Peth, SP Road). Buy from one store where you can to save on shipping.
| Component | Qty | What it does | Approx. cost |
|---|---|---|---|
| Arduino Uno R3 | 1 | Reads the inputs, runs the decision logic written in C/C++ and drives the outputs. | ₹550 |
| IR obstacle sensor module | 1 | Detects an object or line in front of it by reflected infrared light. | ₹45 |
| Relay module | 1 | Switches mains or high-current loads such as lamps, pumps and fans from a low-voltage signal. | ₹70 |
| LEDs (assorted) | 1 | Indicate status. | ₹20 |
| 12 V power adapter / step-down transformer | 1 | Supplies stable low-voltage power from the mains. | ₹250 |
| Passive components, PCB and wiring kit | 1 | Resistors (assorted), capacitors (assorted), PCB / breadboard and cables, connectors and jumper wires. | ₹310 |
| Wiring, PCB, soldering and enclosure | 1 | Project overhead | ₹450 |
| Demo model base / mounting board | 1 | Project overhead | ₹500 |
| Testing spares and replacements | 1 | Project overhead | ₹300 |
| Estimated total | Varies with brand, quality and city | ₹2,100 – ₹3,100 |
Prices are estimates for budgeting. We confirm the bill of materials when your design is frozen, and components are charged at actual cost with bills.
How much does this project cost?
| Option | What you get | Cost |
|---|---|---|
| Components only | You buy the parts and build it yourself | ₹2,100 – ₹3,100 |
| Hardware / IoT Final Year | Working model or guided build, Circuit diagram and bill of materials, Firmware / code with explanation | from ₹9,999 + components |
| Capstone Project (CPE) | Working project or model, Black book in MSBTE format, Step-by-step explanation | ₹9,999 + components |
| Diploma ITR | 100% working source code, Project report PDF, PPT | ₹1,999 + components |
No GST and no hidden charges. Use the cost calculator for a quote with your deadline and add-ons, or see all plans.
Download the project brief (PDF)
Summary, working, components and cost and viva questions on one branded PDF to show your guide or team. To get it developed, contact us on WhatsApp.
What you submit with this project
- Working model with circuit diagram and program code
- Project report or black book in your university's chapter order (block diagram, circuit, calculations, results)
- Presentation for the review and final viva
- Synopsis for topic approval, if your college asks for one
E&TC / ECE viva questions on this project
What is the aim of the Auto Light/Water Saving project?
A system that switches lights and taps based on whether people are present. IR sensors at the door count people entering and leaving, and when the count reaches zero the lights and water supply are switched off automatically.
Explain the working of your project in short.
12 V power adapter / step-down transformer supplies the circuit; a regulator gives the controller and sensors a steady 5 V. The IR obstacle sensor module detects an object or line in front of it by reflected infrared light. The Arduino Uno R3 reads the inputs, runs the decision logic written in C/C++ and drives the outputs. The Relay module switches mains or high-current loads such as lamps, pumps and fans from a low-voltage signal.
What microcontroller is on the Arduino Uno and what are its key specifications?
The Uno uses the ATmega328P: 8-bit, 16 MHz clock, 32 KB flash, 2 KB SRAM, 14 digital I/O pins (6 PWM) and 6 analog inputs with a 10-bit ADC.
How does an IR obstacle sensor work?
An IR LED emits light and a photodiode receives the reflection. When an object is close, more light is reflected and the comparator (LM393) switches the output.
Why is a relay used?
It electrically isolates the 5 V control circuit from the high-voltage load. The controller energises the coil through a transistor, and the contacts switch the load.
Why is a resistor connected in series with an LED?
It limits the current to a safe value (about 10–20 mA). Without it, the LED would draw too much current and burn out. R = (supply voltage − LED voltage) ÷ current.
How is 230 V AC converted to 5 V DC for the circuit?
A transformer steps down the voltage, a bridge rectifier converts AC to pulsating DC, a capacitor smooths it and a 7805 regulator gives a steady 5 V.
Explain the block diagram of your project.
The input section senses the real-world quantity, the Arduino Uno R3 processes it according to the program, and the output section displays the result and drives the actuators. The power supply section feeds every block.
Which communication protocols are used between the modules?
The sensors give digital or analog signals read directly by the controller's I/O and ADC pins, and outputs are driven through transistor or relay drivers.
What is the operating voltage of the circuit?
The controller and most sensors work at 5 V (ESP boards and some modules at 3.3 V). A 12 V adapter powers the board, and a regulator steps it down. Motors and relays get their own supply line so they do not reset the controller.
Related projects
Academic use: Project Buddyy offers mentoring, guidance and reference material for learning. You stay responsible for following your institution's academic integrity rules and for understanding everything you submit.
Want to build Auto Light/Water Saving?
Send your college, deadline and team size. We confirm the scope, cost and what you will submit.