Build Your Own Gas Leak Detector with Arduino – Simple DIY Safety Project

Ever thought about how devices can sniff out gas leaks and keep you safe, without you lifting a finger? That’s where a gas leakage detector comes in. It's a simple yet useful project you can build yourself using Arduino. In this guide, we will walk you through how to make your own gas detection system with all the schematics and code you need to get started.

What is a Gas Leakage Detector?

A gas leakage detector uses MQ-5 gas sensor to identify the presence of combustible gases such as LPG, methane, and smoke in the air. When gas concentration exceeds a certain threshold, it triggers a buzzer and alerts users through a connected display or indicator.

Components Required

To build this project, you will need:

• Arduino Uno
• MQ-5 Gas Sensor
• Buzzer
• LED
• 16x2 LCD Display (with I2C Module)
• Resistors
• Jumper Wires & Breadboard
• 5V Power Supply

Circuit Diagram of Gas Leakage Detector Using Arduino

The MQ-5 sensor’s digital output goes to pin A2, while a buzzer (on A0) and an LED (on A1) provide alerts when gas is detected. A common ground is shared, and you can also power the system using USB or a regular adapter. When gas is detected, the Arduino turns on a buzzer and LED.

Applications of Gas Leakage Detectors

• Home safety and kitchen monitoring
• Industrial gas leak detection
• Smart home automation systems
• Educational electronics and IoT projects

Click here to explore the project in detail: How to Build a Gas Leakage Detector Using Arduino: Complete DIY Guide

Build Your Own RFID-Based Attendance System with Arduino

Keeping track of attendance should not feel like a daily hassle. Whether you are running a classroom, managing a small office, or organizing a community event, a simple, low-cost solution can go a long way. This system reads RFID cards to automatically log check-ins and check-outs, shows updates on an LCD, and stores attendance logs with real-time stamps using an RTC module. It's completely offline and stores data locally—so no need for an internet connection. Best part? The total cost is just around $30.

Why Choose Arduino for DIY RFID Attendance Tracker?

Arduino gives you full control over the system’s features without depending on expensive or limited commercial options. The MFRC522 RFID reader is accurate, and combining it with real-time clock and EEPROM modules means your data is both timestamped and safely stored, even during a power cut. Plus, once built, this setup is fully reusable and expandable for future upgrades like IoT integration or door control.

Key Features of RFID based attendance system

• Automated RFID card scanning for both entry and exit
• Real-time timestamp logging using DS1307 RTC
• Local data storage with EEPROM, survives reboots
• LCD display for live updates
• Menu navigation via push buttons or serial monitor
• Customizable card programming with personal data

Components You’ll Need

• Arduino Uno
• MFRC522 RFID Reader
• DS1307 RTC Module (with built-in AT24C32 EEPROM)
• 16x2 I2C LCD Display
• Push Buttons (x2)
• RFID Cards/Tags
• Breadboard, jumper wires, and 5V–12V power supply

Real-World Applications

• Classrooms – Track student attendance and prevent proxy entries
• Offices – Log employee in/out times without manual input
• Gyms & Clubs – Track member usage, ensure hygiene with contactless logging
• Workshops – Monitor visitor entry or workshop sessions
• Healthcare & Industry – Touchless logging for safety zones or shift tracking

Upgrade Ideas

If you want to go further, here are a few add-ons you can try later:

• Add Wi-Fi for syncing logs to Google Sheets or cloud dashboards

• Use a fingerprint sensor along with RFID for dual authentication

• Add a relay switch to control room access

• Store logs on an SD card for large-scale deployments

This RFID attendance system is a great DIY project for anyone looking to solve a real problem while learning valuable electronics and programming skills. It’s affordable, fully offline, and scalable. Once set up, it can handle real-time check-ins like a pro—and you’ll know exactly how every part works.

Build Your Own Mini Drone Testing Rig with 3D Printing

If you have ever rushed to catch a crashing drone during indoor tests, this one's for you. In this guide, you will learn how to build a Build a 3D Printed Mini Drone Testing Stand, based on the Open Gimbal concept, that keeps your mini drones secure while you test. No more unexpected takeoffs or crash landings.

Why Build a Testing Rig?

• Prevent crashes and protect props and motors
• Fine-tune flight behavior in a controlled environment
• Save money, commercial rigs cost thousands; this one uses only ~$50 in parts

Parts You will Need

3D Printed Components:

• Base, mid‑rings (A&B), outer ring, connectors, drone holder

Mechanical Hardware:

• 603zz bearings ×4

• 606zz bearing ×1

• M6 bolt (50 mm)

• M6 nuts & washers

• M3 bolts (30 mm), nuts & washers

Tools:

• Screwdriver, Allen key, mini pliers

How It Works

1. Base + outer ring are connected via M6 bolt for stability.

2. Mid-rings snap into the outer ring—with or without light sanding—and rotate smoothly.

3. Bearings + M3 bolts hold the mid-rings securely.

4. Drone holder with spacers attaches so your mini-drone can be mounted safely

Assembly Steps

1. Connect base + outer ring using M6 bolt and washers.
2. Insert bearings into outer ring’s edges.
3. Attach mid-rings to outer ring with M3 bolts and nuts (add washers to space parts).
4. Install drone holder, using bearings and bolts, adjust bolt lengths to avoid hitting props.
5. Mount your drone using Velcro or ties—and you’re ready to test

Testing and Tuning

• Mount the drone and spin props at low throttle to check smooth rotation.

• Use the rig to fine-tune flight controls like PID values, free from external influences like wind.

• Test motor/prop combos safely, listening for unusual vibration.

• Diagnose issues by checking clearance and tightening bolts if behavior is erratic

3D models and assembly guides are all open-source and available in the tutorial 

Recommended 3D print settings

• Layer height: 0.2 mm
• Infill: 20–30%
• Supports for overhangs
• Specific orientation files included

You are building a compact, DIY Drone Test Rig that holds your drone securely while allowing free movement on all axes. this project is perfect for safely fine-tuning flight parameters, checking motor thrust, and running diagnostics, without the risk of costly crashes or needing expensive gear.

Ready to get started? Head over to the full tutorial, grab the 3D-print files, and tell us how your test rig turns out.

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Learn How to Send SMS with ESP32 Using SMS API

Forget bulky GSM modules and SIM cards, now you can send real-time SMS alerts with ESP32 using the free SMS API from Circuit Digest Cloud. Perfect for applications like temperature monitoring, motion detection, or door-opening alerts. In this project learn how to deliver instant notifications directly to your phone without any apps, dashboards, and fees.

How It Works

• ESP32 connects to Wi‑Fi using SSID and password.
• It reads sensor data (e.g., temperature via DHT11).
• If a threshold is crossed (e.g., temp ≥ 30 °C), ESP32 sends an HTTP request to the SMS API.
• Circuit Digest Cloud validates your API key and sends an SMS to the linked phone number.

What You Will Need

• ESP32 Development Board
• DHT11 Temperature Sensor (or any sensor of your choice)
• Breadboard + Jumper Wires
• 5V USB Power Supply

Circuit Diagram

Getting Started: SMS API Key

1. Visit Circuit Digest Cloud, sign in or register

2. Generate your free API key (valid for 100 SMS/month)

3. Add recipient phone number(s) via OTP

4. Choose an SMS template (e.g., Template ID 102 for temperature alerts)

Applications of SMS API with ESP32

• Smart Home & Security: Get alerts for critical events

• DIY Prototyping: Fast, hardware-free SMS integration

• Educational Projects: Learn HTTP, JSON, cloud APIs ,  all through ESP32

For a more detailed Explanation and Schematics :  How to send SMS with ESP32 using SMS API

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Complete Guide to Amplitude Modulation (AM)

Amplitude Modulation (AM) is among the earliest and most fundamental methods in wireless communication. It set the stage for long-distance audio broadcasting, taking the place of previous spark-gap transmitters. Whether you are an electronics student or a hobbyist dealing with RF circuits, grasping the principles of AM, both in theory and practice, is crucial. This tutorial will guide you through the concepts of AM, waveforms, circuit design, and testing it using an oscilloscope.

What is Modulation?

Modulation is the process of adding a low-frequency message signal, like audio, to a high-frequency carrier signal. This allows the signal to travel longer distances more efficiently. There are three primary types of analog modulation:

• Amplitude Modulation (AM)
• Frequency Modulation (FM)
• Phase Modulation (PM)

Materials Required

1. BC547 - 1 
2. 7805 - 1 
3. Resistor - 470Ω - 3
4. Resistor - 100Ω - 1
5. Resistor 1KΩ - 1
6. Capacitor - 470nF-2
7. Capacitor - 10pF-1

Amplitude Modulation may be one of the earliest modulation techniques, but its simplicity, educational value, and real-world relevance make it worth exploring. Whether you're preparing for exams, building wireless audio projects, or diving into RF basics, understanding AM is a key milestone in your electronics journey.

For a more detailed Explanation and Schematics :  What is Amplitude Modulation? Complete Guide with Formula, Circuit Diagram & Practical Demo

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Build a Fire and Smoke Alarm with Arduino and SMS Notification

In this DIY project, we’ll show you how to build a smart fire and smoke alarm system using an Arduino UNO R4 Wi Fi, MQ2 gas sensor, flame sensor, and SMS alert functionality. This setup not only detects fire and smoke but also sends real-time SMS alerts to your phone, making it ideal for homes, offices, or small industrial spaces.

How the System Works

This project relies on two key sensors:

• MQ2 Smoke Sensor: Detects smoke or combustible gases like LPG, butane, methane, or hydrogen.
• Flame Sensor: Detects the infrared light emitted by flames.

The Arduino continuously monitors these sensors. When it detects a fire or smoke condition, it activates a buzzer and LED indicators (green for normal, red for alert). Simultaneously, it sends an SMS to a predefined number using circuit digest SMS API over Wi Fi.

Components Required

• Arduino UNO R4 Wi Fi
• MQ2 Gas Sensor
• Flame Sensor
• Buzzer
• Red and Green LEDs
• Jumper Wires and Breadboard
• Power Supply
• Internet connectivity (for SMS alerts via API)

SMS Alert Integration

Instead of using GSM modules, this project leverages the built-in Wi Fi of the UNO R4. By integrating with an SMS API (like Fast2SMS), the system sends out alerts immediately when smoke or fire is detected. This makes the setup cost-effective and more modern.

Applications

• Home and office fire safety
• Industrial safety systems
• Smart IoT-based hazard monitoring
• Remote monitoring for senior care or unattended sites

This Arduino-based fire and smoke alarm is a practical, low-cost project with real-world safety benefits. Its ability to send instant SMS alerts makes it suitable for a variety of smart safety applications. Whether you're a hobbyist or an educator, this is a great project to enhance your IoT and sensor integration skills.

For a more detailed Code Explanation and Schematics :  How to build a Smoke and Fire Alarm System using Arduino with SMS Notification

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Understanding Flip-Flops in Digital Electronics

Flip-flops are basic building blocks in digital electronics that work as simple 1-bit memory devices. In electronics Flip-Flop is "A bistable device with synchronous inputs that changes state only at specified transitions of a clock signal" (IEEE Standard 91/1984)". Unlike regular logic gates that respond instantly to inputs, flip-flops can store a value, either 0 or 1, and keep it until something changes it, usually through an input signal and a clock pulse. 

Because of this ability to hold information, they’re used in many sequential circuits like counters, registers, and parts of memory in microprocessors. The following tutorial will give you a complete understanding of Flip-Flops in Digital Electronics.

Difference Between Latch and Flip-Flop

A latch is level-triggered, meaning its output changes as long as the input is active. A flip-flop is edge-triggered, updating its output only on a specific clock edge (rising or falling).

Transistors → Logic Gates → Latches → Flip-Flops

Types of Flip Flops in Digital Electronics

• SR Flip-Flop: This is the simplest type of flip-flop that uses Set (S) and Reset (R) inputs to store a bit. It’s great for basic memory storage, but it gets a bit tricky when both inputs are active at the same time.

• D Flip-Flop: Captures the value present at its D input when a clock pulse occurs, and this value is maintained as the output until the next clock pulse. This characteristic makes the D flip-flop a fundamental building block in registers, shift registers, and various other memory devices. 

• JK Flip-Flop: Think of it as an improved version of the SR flip-flop that avoids the “invalid” state issue. It can toggle, set, or reset based on its J and K inputs and is very versatile in counters.

• T Flip-Flop: Toggles the output on each clock cycle when T is high. It is particularly useful in applications like counters and control circuits.

Applications of Flip-Flops

• Registers
• Counters
• Finite State Machines (FSMs)
• Pipeline stages

Understanding flip-flops is crucial for anyone interested in digital electronics, as they form the basis for more complex sequential circuits and systems.

For a more detailed explanation and practical demonstrations, refer to the full article on Circuit Digest.: Flip-Flop in Digital Electronics: Types, Truth Table, Logic Circuit and Practical Demonstration

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Build a Gesture-Controlled Drone Using ESP32 and MPU6050

 

Ever thought of flying a drone with just your hand gestures? In DIY Gesture Control Drone, we’ll walk you through building a gesture-controlled LiteWing drone using ESP32 and MPU6050. It’s affordable, beginner-friendly, and works using Python and Bluetooth. Whether you're a hobbyist or student, you’ll find the step-by-step tutorial easy to follow and fun to build

Components Required for Drone Gesture Control Project

• LiteWing Drone with battery 
• VLX5311x ToF Sensor For height hold 
• ESP32 dev module and mpu6050 for gesture control 
• A computer with python installed

Features of Gesture Control Drone DIY Project 

• Gesture Control
• Wireless Communication
• Stable Flying
• Compact and Lightweight

How Gesture Control Works?

Gesture control refers to using, hand movements to operate devices without  physical contact. An MPU6050 sensor detects the tilt and motion of your hand, which is processed by an ESP32 microcontroller. These movements are then sent via Bluetooth, allowing you to fly the drone without a traditional remote. you can get full dettails on our tutorial on ESP32 Air Mouse.

For the complete tutorial, schematics and python code : DIY Gesture Control Drone using Python with LiteWing and ESP32

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Weather Monitoring System Using Arduino UNO R4 WiFi

Learn how to create a simple IoT-based weather monitoring system using the Arduino UNO R4 WiFi. This project collects real-time data, such as temperature, humidity, air quality, rainfall, and atmospheric pressure, and displays the information on a local web dashboard. No cloud service or third-party platform is required, making this setup ideal for offline environments.

Features of the IoT Weather Monitoring System

• Monitors temperature, humidity, air quality, pressure, and rainfall
• Displays real-time readings on a local Wi-Fi dashboard
• Operates without cloud connectivity
• Built with Arduino UNO R4 WiFi, which includes onboard Wi-Fi
• Easy to assemble and customize using basic electronic components

Components Required

To build this system, you'll need the following:

• Arduino UNO R4 WiFi
• DHT11 – Temperature and Humidity Sensor
• BMP180 – Pressure Sensor
• MQ135 – Air Quality Sensor
• Rain Sensor Module
• Breadboard and Jumper Wires
• USB Cable for Programming

Circuit Diagram and Assembly of IoT based Weather Station System

How It Works

Once powered on, each sensor reads environmental data. The Arduino UNO R4 WiFi processes this data and hosts a local web page that displays real-time values. Since the dashboard is served over your local network, there's no dependency on internet access or cloud platforms. Any device connected to the same Wi-Fi can access it.

Real-World Applications

This weather station can be adapted for various use cases:

• Educational Projects – Great for learning about sensors, IoT, and data visualization
• Smart Homes – Monitor indoor/outdoor conditions for automation
• Gardening & Agriculture – Track weather changes for irrigation or crop planning
• Offline Setups – Works in remote areas without relying on cloud platforms

For Arduino code and full tutorial: How to Build an IoT-Based Weather Monitoring System Using Arduino

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DIY Smart Helmet with Alcohol, Drowsiness and Theft Detection Using Arduino Uno

Road accidents are a major global concern, especially involving two-wheeler riders. Many of these accidents are due to drunk driving, drowsiness, or not wearing a helmet. The IoT Based Smart Helmet aims to reduce these risks by integrating safety features directly into the helmet. This project incorporates alcohol detection, drowsiness detection, helmet wear detection, and theft detection to ensure the rider’s safety and enforce responsible riding behavior.

Working Principle

The system is designed to prevent the bike from starting unless all safety conditions are satisfied:

• IR sensor detects if the helmet is worn.
• MQ-3 sensor checks for alcohol in breath.
• If alcohol is detected, buzzer sounds and vehicle stays off.
• Drowsiness detection monitors rider’s alertness.
• RF transmitter sends data from helmet to vehicle.
• Vehicle starts only if all safety conditions are met.

Transmitter Side

• Arduino UNO R3 
• 433 MHz RF Transmitter 
• IR Sensor - wear detection and drowsiness detection
• MQ-3 Sensor - alcohol detection
• LED & Buzzer
• Helmet 
• Breadboard 

Receiver Side

• Arduino UNO R3
• 433 MHz RF Receiver
• 16x2 LCD Display with I2C Module
• 1-Channel Relay Module
• LED & Buzzer
• Breadboard

Applications

• Two-Wheeler Safety
• Smart Transportation
• Theft Prevention
• Educational Tool

For full assembly details and code : Smart Helmet using Arduino

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