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

www.circuitdigest.com   

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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

www.circuitdigest.com 
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