💧 Project Overview

In this lesson, we will connect an Ultrasonic Sensor with ESP32 to measure water level in a tank and control a water pump using a relay.

This system will:

• Measure water level using ultrasonic distance

• Detect LOW and FULL tank condition

• Control motor automatically

• Prevent overflow

• Prevent dry running

📦 Components Used in This Project

• Main microcontroller

• Reads ultrasonic data

• Controls relay

• Handles automation logic

🔹 2️⃣ HC-SR04 Ultrasonic Sensor

• Measures distance to water surface

• Calculates water level

• Non-contact measurement

🔹 3️⃣ Single Channel Relay Module

• Controls high voltage motor

• Electrically isolates ESP32

🔹 4️⃣ DC Water Pump

• Pumps water into tank

• Controlled via relay

🔹 5️⃣ 12V Power Supply

• Powers water pump

• External supply required

🔌 Circuit Connections

🔹 Ultrasonic Sensor → ESP32

⚠ IMPORTANT:
Echo pin gives 5V output.
Use a voltage divider (10k + 20k resistor) to reduce to 3.3V for ESP32 safety.

🔹 Relay Module → ESP32

⚠ Relay Active LOW
LOW → Motor ON
HIGH → Motor OFF

🔹 Relay → DC Pump Wiring

When relay activates:
COM connects to NO → Pump turns ON

📐 How Ultrasonic Sensor Measures Water Level

1️⃣ Sensor sends ultrasonic pulse
2️⃣ Pulse hits water surface
3️⃣ Echo returns
4️⃣ ESP32 calculates distance

Formula used:

If tank height = 30 cm:

Water Level = Tank Height – Measured Distance

Example:

⚡ Power Distribution

• ESP32 powered by USB

• Ultrasonic powered by 5V

• Relay powered by 5V

• Pump powered by 12V external supply

⚠ Always connect all GND together (Common Ground)

🚨 Important Safety Notes

✔ Use voltage divider for Echo pin
✔ Never connect pump directly to ESP32
✔ Use proper insulated wiring
✔ Keep ultrasonic sensor dry
✔ Mount sensor firmly at tank top

🎯 What Students Learn in This Lesson

• Ultrasonic sensor interfacing

• Distance measurement concept

• Relay module wiring

• Motor control circuit

• Power isolation

• Industrial-style wiring

📌 Lesson Summary

In this lesson, we successfully:

• Connected HC-SR04 ultrasonic sensor with ESP32

• Connected relay module safely

• Designed pump control circuit

• Built a complete hardware foundation for Smart Water Management System

This makes the system:

✔ More accurate
✔ Non-contact measurement
✔ Industry-ready
✔ Long-lasting solution