Hardware Setup Guide

System Overview

The WLeaks system uses three YF-S201 flow meters positioned at entry, middle, and exit points of a water circuit. An Arduino Mega 2560 reads pulse signals from the sensors and communicates with a Node.js server over USB serial. When a leak or blockage is detected, the Arduino triggers a relay module to shut off the water pump.

Why 3 sensors? By comparing flow rates at multiple points, we can detect where issues occur. If sensor 1 reads high but sensor 2 reads low, there's a leak between them.

Required Components

Arduino Mega 2560

ATmega2560 microcontroller
54 digital I/O pins
16 analog inputs
USB serial communication
Operating voltage: 5V

YF-S201 Flow Meter (×3)

Hall-effect sensor
Flow range: 1-30 L/min
Pulse frequency: F = 7.5 × Q
Working voltage: 5-18V DC
G1/2" thread connection

12V DC Submersible Pump

Voltage: 12V DC
Current: 1.8A @ 12V
Flow rate: 12 L/min
Motor speed: 8500 RPM
Tubing: 16mm diameter
Material: Stainless steel

ZE-4F180 Solenoid Valve

Voltage: 12V DC
Normally closed (NC)
Thread: G1/2"
Max pressure: 0.8 MPa
Response time: <0.15s

5V Relay Module

Input: 5V DC
Optocoupler isolated
Rating: 10A/250VAC
Trigger: Active LOW
LED status indicator

Modified ATX PSU

12V rail: Pump power
5V rail: Logic circuits
Green wire to GND: Always ON
Repurposed from old PC

Additional Materials

LM2596 DC-DC Buck Converter (adjustable, 3A max)
16mm silicone tubing (food-grade)
Jumper wires (male-to-male, male-to-female)
Breadboard or prototype PCB
Water container (bucket or tank)

Wiring Diagram

┌────────────────────────────────────────────────────────────────────┐ │ WATER CIRCUIT │ │ │ ┌──────────┐ │ ┌──────────┐ ┌──────────┐ ┌──────────┐ │ │ WATER │─────────────────┼───►│ SENSOR 1 │─────►│ SENSOR 2 │─────►│ SENSOR 3 │───────────────┼───┐ │ PUMP │ │ │ (Entry) │ │ (Mid) │ │ (Exit) │ │ │ └────┬─────┘ │ └────┬─────┘ └────┬─────┘ └────┬─────┘ │ │ │ │ │ │ │ │ │ │ 12V │ │ Signal │ Signal │ Signal │ │ │ │ │ │ │ │ │ ┌────┴─────┐ │ ┌────┴─────────────────┴─────────────────┴────┐ │ │ │ RELAY │◄────────────────┼────│ ARDUINO MEGA │ │ │ │ MODULE │ Pin 5 │ │ │ │ │ └────┬─────┘ │ │ Pin 21 ◄─── Sensor 1 Signal (Yellow) │ │ │ │ │ │ Pin 20 ◄─── Sensor 2 Signal (Yellow) │ │ │ ┌────┴─────┐ │ │ Pin 19 ◄─── Sensor 3 Signal (Yellow) │ │ │ │ ATX PSU │ │ │ Pin 5 ───► Relay Control │ │ │ │ 12V/5V │ │ │ 5V ───► Sensors VCC (Red) │ │ │ └──────────┘ │ │ GND ───► Sensors GND (Black) │ │ │ │ │ USB ───► Computer (Serial) │ │ │ │ └─────────────────────────────────────────────┘ │ │ │ │ ▼ │ BACK TO TANK └────────────────────────────────────────────────────────────────────┘

Safety First! Always disconnect power before making wiring changes. 12V circuits can cause burns and damage components if shorted.

Pin Connections

Component	Wire Color	Arduino Pin	Notes
Flow Meter 1 (Entry)	Yellow (Signal)	Pin 21	Interrupt-capable pin
Flow Meter 2 (Mid)	Yellow (Signal)	Pin 20	Interrupt-capable pin
Flow Meter 3 (Exit)	Yellow (Signal)	Pin 19	Interrupt-capable pin
All Flow Meters VCC	Red (+5V)	5V	Connect all to 5V rail
All Flow Meters GND	Black (GND)	GND	Common ground
Relay Module IN	Blue (Control)	Pin 5	Digital output
Relay Module VCC	Red (+5V)	5V	Logic power
Relay Module GND	Black (GND)	GND	Common ground

Assembly Steps

Prepare the Power Supply

Short the green wire (PS_ON) to any black wire (GND) on the ATX PSU's 24-pin connector to make it always-on. Identify the 12V (yellow) and 5V (red) rails.
Connect Flow Meters to Water Circuit

Install the three YF-S201 sensors in-line with the water tubing. Ensure the flow direction arrows on the sensors match your water flow direction. Use hose clamps for secure connections.
Wire Flow Meters to Arduino

Connect each sensor's signal wire (yellow) to the designated interrupt pins (21, 20, 19). Connect all red wires to 5V and all black wires to GND. Use a breadboard if needed.
Connect the Relay Module

Wire the relay's IN pin to Arduino Pin 5. Connect VCC to 5V and GND to ground. The relay's COM and NO terminals connect to the pump's 12V power circuit.
Setup the Water Pump Circuit

Connect the 12V PSU output through the relay to the pump. When the relay is activated, it breaks the 12V circuit, stopping the pump.
Upload Arduino Code

Upload arduinocode.ino to the Arduino via USB. The code reads pulses from sensors using interrupts and sends data every second over serial at 115200 baud.
Run the Server

Install dependencies with npm install and start the server with npm start. Update the serial port path in server.js if needed.

High Current Warning! The water pump draws 1.8A at 12V. Use appropriate wire gauge (18 AWG or thicker) and ensure your relay is rated for this current.

Sensor Calibration

Each YF-S201 sensor has a calibration factor that converts pulses to volume. The standard formula is:

Flow Rate (L/min) = Pulse Frequency (Hz) / 7.5

However, actual factors may vary. Our measured calibration factors are:

Sensor	Calibration Factor	Location
Sensor 1	`342.5` pulses/L	Entry Point
Sensor 2	`314.0` pulses/L	Mid Point
Sensor 3	`438.5` pulses/L	Exit Point

To calibrate: Measure a known volume (e.g., 1 liter) and count the pulses. Divide total pulses by volume to get your specific calibration factor.

Troubleshooting

No pulse readings

Check sensor wiring (signal to correct interrupt pin)
Verify 5V power to sensors
Ensure water is actually flowing through the sensor
Check for air bubbles in the tubing

Erratic readings

Add a 10μF capacitor between VCC and GND near each sensor
Keep signal wires away from power cables
Check for loose connections

Relay not switching

Verify relay is receiving 5V on VCC
Check if relay is active-HIGH or active-LOW
Test with a simple Arduino blink sketch on Pin 5