95DB Alarm DC 3-24V SFM-27 Electronic Buzzer Passive Continuous Piezoelectric - Image 1
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95DB Alarm DC 3-24V SFM-27 Electronic Buzzer Passive Continuous Piezoelectric - Image 4

95DB Alarm DC 3-24V SFM-27 Electronic Buzzer Passive Continuous Piezoelectric

Passive Buzzer Alarm Module Sensor Continuous Beep Arduino Raspberry Pi
DC 3-24V 12V 2-Wire Intermittent Active Electronic Buzzer Alarm White SFM-27
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100+ 17.5 % $4.54

Description

Experience the convenience of the 95dB Alarm DC 3-24V SFM-27 Electronic Buzzer – your ideal solution for effective auditory alerts. Crafted in a sleek black hue, this passive buzzer boasts a diameter of 22.5mm and stands at a height of 11mm, making it a compact yet powerful addition to your setup.

Designed for versatility, this electronic marvel features two mounting holes strategically positioned at a 30mm distance, ensuring easy installation. The two wires, each extending to a length of 100mm, provide ample room for flexibility during setup.

Engineered with precision, the SFM-27 operates as a piezoelectric buzzer, known for its reliability and consistent performance. Emitting a sound pressure level of 95 dB, it guarantees that alerts won’t go unnoticed. Its broad operating voltage range, spanning from 3 to 24VDC, offers compatibility with various systems.

Notably efficient, the SFM-27 consumes a maximum current of 10mA, striking an ideal balance between performance and energy efficiency. The frequency, finely tuned at 3900±500Hz, ensures a clear and attention-grabbing tone that suits diverse applications.

Designed for ease, the SFM-27 comes equipped with convenient mounting holes, streamlining the installation process. Whether you require a dependable alert system or seek to enhance user experiences, this electronic buzzer delivers consistent, high-quality performance that resonates.

📌 Code Examples & Usage – Passive Piezoelectric Buzzer (3–24V, 95dB)

📋 Overview

This passive piezoelectric electronic buzzer requires an external signal to generate sound. Unlike active buzzers, it does not contain an internal oscillator, meaning the sound frequency and pattern are fully controlled by your microcontroller or PLC output.

It is ideal for applications where you need:

  • Adjustable tone or pitch

  • Beeps, melodies, or alert patterns

  • User feedback sounds

  • Educational electronics projects

  • Arduino, ESP32, ESP8266, and PLC systems

⚙ Key Features

  • Type: Passive piezoelectric buzzer

  • Wiring: 2-wire

  • Operating voltage: 3–24V DC

  • Sound level: ~95dB

  • Continuous tone capability

  • Requires external frequency or PWM signal

⚠ IMPORTANT – Passive vs Active (READ THIS)

🚨 This is a PASSIVE buzzer

✔ Requires a PWM / square-wave signal
✔ Tone and pitch are fully adjustable
✔ Can play melodies and patterns

❌ Will NOT make sound if DC power is applied alone

📌 If you want a buzzer that sounds automatically when powered, choose an active buzzer instead.

🔌 Wiring Basics (2-Wire)

Wire Function
+ Signal / PWM
– Ground

📌 Polarity usually matters for best performance.

🔌 Arduino / ESP32 Wiring (Low Voltage Use)

For 3.3V–5V operation, the buzzer can often be driven directly from a GPIO pin.

Buzzer Arduino
+ D9 (PWM pin)
– GND

📌 For higher voltages (12–24V), use a transistor or MOSFET.

🔌 High-Voltage / PLC Wiring (Recommended)

Use a transistor or relay to switch the buzzer when driven from PLCs or microcontrollers.

MCU / PLC OUT ──► Transistor / Relay ──► Buzzer +
Buzzer – ───► Supply GND

🧪 Arduino Example – Basic Beep Using tone()

const int buzzerPin = 9;

void setup() {
pinMode(buzzerPin, OUTPUT);
}

void loop() {
tone(buzzerPin, 1000); // 1kHz tone
delay(500);
noTone(buzzerPin);
delay(500);
}

✔ Simple and beginner-friendly.

🧪 Frequency & Pitch Example

void loop() {
tone(9, 500); // Low pitch
delay(500);
tone(9, 1500); // Higher pitch
delay(500);
noTone(9);
delay(1000);
}

📌 Frequency controls pitch — higher frequency = higher tone.

🧪 Melody Example (Simple Alert)

int buzzerPin = 9;
int melody[] = {1000, 1200, 1500, 1000};
int durations[] = {200, 200, 200, 400};

void setup() {}

void loop() {
for (int i = 0; i < 4; i++) {
tone(buzzerPin, melody[i]);
delay(durations[i]);
noTone(buzzerPin);
delay(50);
}
delay(2000);
}

🔋 Power Notes

  • For 3–5V: GPIO pin drive is usually acceptable

  • For 12–24V: Use transistor, MOSFET, or relay

  • Do not exceed buzzer voltage rating

  • Share common ground between controller and power supply

🧠 Common Issues & Fixes

Issue Cause Fix
No sound DC only Use PWM / tone()
Very quiet Low frequency Increase frequency
MCU resets Overcurrent Use transistor
Constant tone PWM stuck HIGH Use noTone()
Wrong pitch Frequency mismatch Adjust tone value

Additional information

Weight 20 g
Dimensions 260 × 160 × 20 mm

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