PIR Dog Bark Stopper (Ultrasonic Deterrent)

Project Overview

This project creates a humane dog bark deterrent that uses ultrasonic sound to discourage excessive barking. The system activates only when motion is detected, saving battery life and preventing constant noise. When the sensor detects a dog (or person), it emits a high-frequency sound (25-30 kHz) that is unpleasant to dogs but inaudible to humans.

Difficulty: Intermediate
Estimated time: 2-3 hours
Estimated cost: $25-35

How It Works

A PIR sensor detects motion (the dog approaching). When motion is detected, the system activates an ultrasonic transducer that emits a high-frequency tone. Dogs find this sound unpleasant and learn to associate the area with the sound, eventually reducing barking behavior. An optional sound sensor can be added to only activate when barking is actually occurring.

Materials Needed

Arduino Nano or ESP32 (1)
HC-SR501 PIR sensor (1)
Ultrasonic transducer (25-30 kHz, e.g., Murata MA40S4S)
ULN2003 Darlington array or MOSFET (to drive transducer)
Sound sensor module (LM393-based, optional)
LED for status indication
220Ω resistor
Jumper wires
Power supply (5V 1A)
Weatherproof enclosure (if outdoor use)

Circuit Diagram

Connection Table

VCC

GND

OUT

Digital Pin 2

–

Digital Pin 9 (via ULN2003)

–

GND

Digital Pin 3

Anode

Digital Pin 13 (via 220Ω)

表

Arduino Code

// PIR Dog Bark Stopper

const int pirPin = 2;
const int ultrasonicPin = 9;
const int soundSensorPin = 3;
const int ledPin = 13;

const int halfPeriod = 20;
unsigned long lastTriggerTime = 0;
const unsigned long deterrentDuration = 3000;
const unsigned long cooldownPeriod = 60000;
bool deterrentActive = false;
unsigned long deterrentStart = 0;

void setup() {
  Serial.begin(9600);
  
  pinMode(pirPin, INPUT);
  pinMode(ultrasonicPin, OUTPUT);
  pinMode(soundSensorPin, INPUT);
  pinMode(ledPin, OUTPUT);
  
  digitalWrite(ultrasonicPin, LOW);
  digitalWrite(ledPin, LOW);
  
  Serial.println("Dog Bark Stopper Ready");
  delay(60000);
}

void generateUltrasonicTone() {
  for (int i = 0; i < 1000; i++) {
    digitalWrite(ultrasonicPin, HIGH);
    delayMicroseconds(halfPeriod);
    digitalWrite(ultrasonicPin, LOW);
    delayMicroseconds(halfPeriod);
  }
}

void activateDeterrent() {
  if (millis() - lastTriggerTime > cooldownPeriod) {
    deterrentActive = true;
    deterrentStart = millis();
    lastTriggerTime = millis();
    
    digitalWrite(ledPin, HIGH);
    
    while (millis() - deterrentStart < deterrentDuration) {
      generateUltrasonicTone();
    }
    
    digitalWrite(ledPin, LOW);
    deterrentActive = false;
  }
}

bool isBarking() {
  return digitalRead(soundSensorPin) == HIGH;
}

void loop() {
  bool motionDetected = digitalRead(pirPin) == HIGH;
  bool barking = isBarking();
  
  if (motionDetected) {
    activateDeterrent();
  }
  
  delay(100);
}

Installation Steps

Assemble circuit on breadboard and test with oscilloscope
Test with a known dog to verify reaction (look for ear perk, head tilt)
Adjust frequency for different dogs (20-30kHz)
Mount unit where the dog frequents at appropriate height (0.5-1m)
Observe behavior over several days to see if barking reduces

Safety Considerations

This device is meant to discourage excessive barking, not to punish
The deterrent should only activate briefly when motion is detected
The sound should be inaudible to humans; if you can hear it, the frequency is too low
Not for use on puppies (very young dogs may be more sensitive)
Check local regulations regarding ultrasonic devices

Project Extensions

Add sound sensor to only trigger when barking is actually occurring
Add ESP32 to send notifications when the deterrent activates
Track how often the device activates to measure barking frequency
Add Bluetooth to manually trigger from phone
Add water sprayer for stubborn dogs (less humane)

Conclusion

This humane bark deterrent can help reduce excessive barking without causing pain or distress. Combined with positive reinforcement training, it can be an effective tool for managing nuisance barking.