10PCS HDX2 SW420 Normally Closed Vibration Sensor Vibration Switch Compact, reliable vibration detection for prototyping, security, and equipment monitoring. Each HDX2 SW420 is a normally closed mechanical vibration switch that opens when exposed to sufficient vibration or shock. Sold as a set of 10 for smallbatch projects, repairs, or repeated testing. Why you need it Simple vibration detection without complex electronics — ideal for rapid prototyping and replacement parts. Normally closed behavior provides a failsafe default (circuit closed when idle); an open circuit indicates vibration, which simplifies alarm and monitoring logic. Lowcost, repeatable performance across multiple units — useful for multipoint sensing or distributing spares on a project. Key benefits Readytouse: small mechanical switch requires no calibration or special power supply. Consistent response: designed to trigger reliably on knocks, taps, and vibration events. Economical pack: 10 pieces let you deploy sensors across several locations or keep extras for development. Main features and attributes Model: HDX2 SW420 — standardized vibration switch module. Switch type: Normally closed mechanical vibration switch (opens on vibration). Functionality: Detects physical vibration or shock and changes contact state for simple digital monitoring. Construction: Robust mechanical design for repeated switching; standard leads/pins for straightforward wiring. Compatibility: Works with common digital inputs, relay circuits, microcontrollers (Arduino, Raspberry Pi, etc.), alarm panels, and other monitoring systems. Use with a pullup or pulldown configuration depending on your circuit design. Size and installation: Compact form factor suited for mounting inside enclosures or on equipment; mounting orientation may affect sensitivity — test placement for results. Performance: Reliable switching response for generalpurpose vibration detection and alarm applications. Typical applications Security and alarm systems: Detect vibration or tampering on doors, windows, safes, or display cases to trigger alerts. Machinery and equipment monitoring: Spot abnormal vibration in motors, pumps, or compressors as an early warning of mechanical issues. DIY electronics and education: Integrate into microcontroller projects for motion sensing, impact detection, or interactive devices. Quick setup tips Connect the two sensor leads to your circuit input and ground (or to a digital input and voltage through a pullup/pulldown resistor depending on your design). Test different mounting positions and fastening methods to achieve the desired sensitivity level; direct contact with the monitored surface improves responsiveness. Debounce in software if using microcontroller inputs to avoid false triggers from bounce or transient shocks. What's included 10 x HDX2 SW420 Normally Closed Vibration Sensor Vibration Switches This pack provides a practical, lowcost way to add vibration sensing to small projects, prototypes, or maintenance kits.