JSN-SR04T / AJ-SR04M Waterproof Ultrasonic Distance Sensor | ATMOSFÆR ENGINEERING

Waterproof ultrasonic ranging module with integrated sealed probe for harsh environments. Measures distances from 25cm to 4.5m using ultrasonic pulse detection. Features separate waterproof transducer connected via cable for wet locations. Compatible with Arduino, ESP32, STM32, and other 5V microcontrollers. Ideal for water level monitoring, outdoor robotics, vehicle detection, and industrial sensing applications.

Technical Specifications:

• Model: JSN-SR04T / AJ-SR04M
• Operating Voltage: 5V DC
• Quiescent Current: 5mA
• Working Current: 30mA
• Ultrasonic Frequency: 40kHz
• Measuring Range: 0.25m - 4.5m (25cm - 450cm)
• Blind Zone: 25cm (minimum distance)
• Resolution: ~0.5cm
• Accuracy: ±1cm (typical)
• Detection Angle: <50° beam width
• Interface: TTL level (Trig/Echo pins)
• Response Time: ~30-50ms per measurement
• Operating Temperature: -10°C to +70°C
• Storage Temperature: -20°C to +80°C
• Protection: IP67 waterproof transducer (sealed probe)
• Module Dimensions: 41mm x 28.5mm
• Cable Length: ~2.5m (typical, connects module to waterproof probe)

Pin Configuration:

• VCC/+5V: Power supply (5V DC)
• GND: Ground
• Trig/TX: Trigger input (send 10μs pulse to trigger measurement)
• Echo/RX: Echo output (returns pulse width proportional to distance)

Working Principle:

1. Send 10μs+ high pulse to Trig pin
2. Module transmits 8x 40kHz ultrasonic pulses
3. Echo pin goes HIGH when echo detected
4. Echo pulse width = time-of-flight
5. Distance = (pulse width × 340m/s) / 2

Features:

• Fully waterproof ultrasonic transducer (IP67)
• Separate control module and sensor probe
• Low power consumption
• High anti-interference capability
• Wide voltage range compatibility
• Small, compact design
• Long cable for flexible installation

Applications:

• Water level and liquid level monitoring
• Outdoor distance measurement
• Robot obstacle avoidance (wet environments)
• Vehicle/object detection systems
• Parking sensors
• Industrial automation and control
• Smart agriculture (irrigation monitoring)
• Security and intrusion detection

Comparison to HC-SR04:

• Waterproof transducer vs open PCB sensor
• Longer range (4.5m vs 4m)
• Better suited for outdoor/wet applications
• Similar interface and operation

Compatible with Arduino, ESP32, Raspberry Pi, STM32, and any 5V microcontroller with GPIO. Sample code available for Arduino IDE.