SW-420 Vibration Sensor Module

SW-420 Vibration Sensor Module

Normally Closed (NC) Design | Adjustable Sensitivity | Smart Home & Alarm Systems

The SW-420 Vibration Sensor Module is a high-precision digital input device used to detect vibration, shocks, tilts, or physical movement. It features an onboard SW-420 highly sensitive vibration element combined with an LM393 voltage comparator to provide a stable, clean digital output signal.

Because it is a Normally Closed (NC) sensor, it is remarkably power-efficient and highly immune to minor static interference, making it an excellent choice for anti-theft alarms, smart motorcycle/car alarms, earthquake detection systems, and automated wakeup switches.

????️ Key Features

• Normally Closed (NC) Architecture: Under stable, non-vibrating conditions, the internal sensor switch is closed (conducting), outputting a steady low logic state. When a shake or vibration occurs, the internal contact momentarily opens, triggering a state change.

• Adjustable Sensitivity: Features an onboard precision blue potentiometer. Turning it allows you to fine-tune the exact amount of mechanical impact or vibration required to trigger the output.

• Onboard LM393 Comparator: Amplifies and cleans the raw sensor output, providing a reliable, sharp digital wave signal ($>15\text{mA}$ driving capability).

• Dual LED Indicators: * Power LED: Glows continuously when the module is receiving stable power.

o Status/Switch LED: Turns off or flashes when vibration is actively detected and the threshold is breached.

• Compact Layout: Miniature footprint with a pre-drilled fixed bolt hole ($3\text{mm}$) for quick and rigid mounting onto project chassis.

???? Technical Specifications

Parameter Specification

Operating Voltage $3.3\text{V} - 5\text{V}$ DC

Output Type Digital Logic Output ($0$ and $1$)

Sensor Element SW-420 Normally Closed Vibration Switch

Comparator IC LM393 Low-Power Voltage Comparator

Output Current Drive $\geq 15\text{mA}$

Dimensions Approx. $32\text{mm} \times 14\text{mm} \times 7\text{mm}$

???? Pinout Configuration

The module features a standard 3-pin layout that makes it easy to interface directly with Arduino, Raspberry Pi, ESP8266, or standard relay modules:

1. VCC: Connect to a $3.3\text{V}$ to $5\text{V}$ DC power supply.

2. GND: Connect to circuit Ground (negative power terminal).

3. DO (Digital Output): The primary signal output.

o Normal / Quiet state: Outputs LOW ($0\text{V}$).

o Vibration detected: Toggles HIGH ($VCC$) for the duration of the physical shock.

⚙️ How it Works & Calibration

The heart of this module is a tiny metallic spring housed inside a capsule alongside a small conductive post.

1. At Rest: The spring rests naturally against the post, completing the circuit (Normally Closed). The module outputs a LOW logic level.

2. When Vibrated: The mechanical shock causes the spring to shake and lose contact with the central post. The circuit breaks instantly, prompting the LM393 comparator to drive the DO pin HIGH.

3. Calibration: If the module is too sensitive (triggering from tiny ambient vibrations), turn the blue potentiometer counter-clockwise slightly to lower its sensitivity. If it fails to register heavy impacts, turn it clockwise.

???? Package Includes

• 1 x SW-420 Normally Closed Vibration Sensor Module