Piezo Disc Type Tap/Vibration Sensor Switch Module

Description

The Piezo Disc Tap/Vibration Sensor Module is a compact, low-cost detection board built around a piezoelectric ceramic disc. Unlike mechanical ball or spring switches, the piezo element generates a voltage spike when mechanically stressed—tapping, knocking, or vibrating the disc causes it to bend slightly, producing a measurable electrical signal proportional to the force applied . The module adds an LM393 comparator with an adjustable potentiometer, converting the raw piezo signal into a clean digital output while also exposing the analog voltage for intensity measurement.

The module typically provides both analog (AO) and digital (DO) outputs. The AO pin outputs a voltage that increases with vibration intensity, while the DO pin switches HIGH when vibration exceeds the potentiometer-set threshold . This dual-output design makes the module suitable for both simple tap detection (using DO) and more nuanced intensity-based applications like electronic drums or knock pattern recognition (using AO). The module operates from 5V DC (some variants accept 3.3V), and the onboard potentiometer allows sensitivity adjustment from light taps to firm knocks.

Critical limitation: The raw piezo output can produce voltage spikes exceeding 5V during hard impacts, potentially damaging microcontroller inputs . Most modules include protection circuitry (zener clamping), but verify your specific board. Also note that the digital output pulse is often very brief—for reliable relay control or alarm latching, a monostable circuit (e.g., 555 timer) or software latch is recommended .

Features

• Piezoelectric Sensing Element: Generates voltage from mechanical stress—no power required for the sensing element itself; responds to taps, knocks, and surface vibration .

• Dual Outputs (AO + DO): Analog output for intensity measurement and digital output for threshold-based tap detection .

• Adjustable Sensitivity Potentiometer: Onboard trimpot sets the digital trigger threshold; some boards allow adjustment from “mouth blow” sensitivity to firm tap detection .

• LM393 Comparator: Provides clean digital switching with TTL-level output .

• Compact PCB: Small footprint (approximately 20×20mm or similar) with mounting holes for surface coupling .

• 5V DC Operation: Standard 5V supply; some variants may accept 3.3V (verify with supplier).

• Indicator LED: Visual feedback when digital output triggers .

• Simple Interface: Four pins: VCC, GND, AO, DO .

Technical Specifications