Introduction
The Ultrasonic Sensor (HC-SR04) is one of the most widely used distance-measuring sensors in electronics and robotics. Its accuracy, low cost, and simplicity make it perfect for beginners, DIY projects, and even industrial automation.
How Does an Ultrasonic Sensor Work?
Ultrasonic sensors use sound waves above human hearing range (typically 40 kHz) to measure distance.
Here’s the simple breakdown:
-
Trigger pin sends out an ultrasonic pulse.
-
The pulse travels through the air.
-
It hits an object and bounces back.
-
The Echo pin receives the reflected wave.
-
The sensor calculates distance using:
Distance = (Time × Speed of Sound) / 2
This makes it extremely useful for detecting objects without touching them.
Key Features
-
Measuring range: 2 cm to 400 cm
-
Accuracy: ±3 mm
-
Works in daylight and darkness
-
Easy to interface with Arduino, Raspberry Pi, ESP32, etc.
Applications
-
Robot obstacle avoidance
-
Automatic parking systems
-
Smart dustbins
-
Water level measurement
-
Security systems
-
Industrial automation
Conclusion
The HC-SR04 ultrasonic sensor is an essential tool for any electronics learner. It’s cheap, reliable, and teaches you the fundamentals of distance detection and embedded development.
