SW-420 vibration sensor module

The SW-420 Vibration Sensor Module is a digital vibration detection module built around a SW-420 vibration switch and an LM393 comparator chip. It senses vibration, shock, or sudden motion and outputs a simple HIGH/LOW digital signal — perfect for microcontrollers like Arduino, ESP32, Raspberry Pi, etc.

🔌 Electrical & Performance Specs
Parameter Value / Description
Operating Voltage 3.3 V – 5 V DC (works well with most microcontrollers)
Operating Current ~15 mA typical (depends on environment & LEDs)
Output Type Digital (Logic HIGH/LOW) — easy binary signal
Comparator IC LM393 (gives stable output)
Sensitivity Adjustment On-board potentiometer to tune trigger threshold
Indicator LEDs Power and output LEDs for visual feedback
PCB Size ~32 × 14 × 7 mm (compact)
Output Logic (typical) LOW when vibration detected, HIGH when idle
Sensor Type Normally-closed vibration switch
Operating Temp Range ~-40 °C to +85 °C (wide range for many environments)
🔍 How It Works (Simplified)

Vibration switch inside the SW-420 is normally closed (contacts connected).

When vibration/shock occurs, the internal mechanism breaks contact briefly.

That change is read by the LM393 comparator, which produces a clean digital signal.

The output pin toggles — typically LOW on vibration, HIGH when still — but this can depend on board wiring.

A potentiometer (trim pot) lets you dial the sensitivity up or down.

🔌 Typical Pinout
VCC → Power (+3.3 V to +5 V)
GND → Ground
DO → Digital Output

You’ll often see two LED indicators: one for power, one for output/signal status.

💡 Applications

This module is great for:

🚨 Alarm systems (detect knocks/impact on doors, windows, safes)

🤖 Robotics & automation triggers (e.g., bump detection)

🏠 Security detectors (vibration on appliances or structural elements)

🧪 DIY projects/experiments (detect motion, shakes, breaches)

🧠 Quick Usage Tips

Connect DO to a microcontroller digital pin and read HIGH/LOW.

Adjust the potentiometer gently to set how strong a vibration must be to trigger detection.

Keep in mind that very strong ambient vibration or noise can cause frequent triggering, so calibration is key.

📦 Example Arduino Logic (conceptual)

const int sensorPin = 2; // DO pin
void setup() {
pinMode(sensorPin, INPUT);
Serial.begin(9600);
}

void loop() {
int state = digitalRead(sensorPin);
if (state == LOW) {
Serial.println("Vibration detected!");
} else {
Serial.println("No vibration.");
}
delay(200);
}