2cm-400cm range, 5V, 15° beam angle
| Range | 2cm - 400cm |
|---|---|
| Current | 15mA |
| Voltage | 5V DC |
| Accuracy | 3mm |
| Frequency | 40Hz |
The HC-SR04 measures distance by sending a 40kHz ultrasonic pulse and timing the echo return. It covers 2cm to 400cm with 3mm accuracy — making it the standard choice for obstacle avoidance, water level detection, and proximity alarms in Indian maker projects.
Trigger the TRIG pin for 10 microseconds. The sensor sends 8 ultrasonic pulses and waits for echo. Measure the ECHO pin HIGH duration in microseconds, divide by 58 — that gives you distance in centimetres. Simple to implement in Arduino, ESP32, or Raspberry Pi.
Robot obstacle avoidance (pair with L298N Motor Driver), underground water tank level monitoring, parking distance alerts, and automatic door/gate triggers. At ₹59 per unit, it is practical to use multiple sensors for 360° coverage.
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