SW-420 Normally Closed Vibration Sensor Module – Alarm Trigger Sensor with Adjustable Sensitivity

Description

The SW-420 Vibration Sensor Module is a compact, low-cost motion detection board designed for alarm systems, anti-tamper devices, and vibration monitoring applications. It uses a normally-closed spring-switch sensing element (the SW-420) combined with an LM393 voltage comparator to convert mechanical vibration into a clean digital output signal . When the module is stationary, the internal spring maintains contact. When vibration or tilt occurs, the spring briefly loses contact, changing the comparator’s input state and triggering a digital output transition .

The module operates from 3.3V to 5V, making it directly compatible with Arduino, ESP32, and most microcontroller platforms. An onboard potentiometer allows the vibration sensitivity threshold to be adjusted, enabling users to tune the module for different environments—from detecting gentle door knocks to monitoring heavy machinery . Power and output indicator LEDs provide visual feedback during calibration and troubleshooting. The compact PCB measures approximately 32×14mm with mounting holes for secure installation .

Important limitation: The SW-420 detects vibration presence, not vibration magnitude, frequency, or direction. It is not an accelerometer and cannot measure movement distance or speed . For applications requiring quantitative vibration analysis, a proper accelerometer or piezoelectric sensor should be used.

Features

• Normally Closed Spring Switch Element: The internal SW-420 switch maintains contact at rest and opens briefly during vibration, providing sensitive non-directional detection .

• LM393 Comparator with Clean Digital Output: Provides stable HIGH/LOW switching with good driving capability (>15mA) for direct microcontroller or relay interfacing .

• Adjustable Sensitivity Potentiometer: Onboard trimmer allows threshold tuning to prevent false triggers from ambient vibration .

• Wide Voltage Compatibility (3.3V–5V): Works with both 3.3V and 5V logic systems, including Arduino and ESP32 .

• Dual LED Indicators: Power LED and output status LED simplify calibration and troubleshooting .

• Compact PCB with Mounting Holes: Approx. 32×14mm board with bolt holes for secure installation .

• Low Power Consumption: Approximately 15mA during operation, suitable for battery-powered and embedded applications .

• Non-Directional Detection: Responds to vibration and tilt from any orientation .

Technical Specifications