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SFM-27 Continuous Tone DC3-24V Electronic Buzzer (Model: HYT-3015B) – Piezo Alarm for Industrial & DIY Applications – White

SKU: FA3048-5
Model

SFM-27 (HYT-3015B)
Buzzer Type

Piezoelectric Active Buzzer (built-in oscillator)
Operating Voltage

DC 3V – 24V
Rated Voltage

12V DC
Resonant Frequency

3100Hz ± 500Hz
Sound Pressure Level

85dB – 95dB @ 10cm
Current Consumption

~12–20mA (typical)
Package Size

Φ30mm × 15mm, wire length ~11cm

The SFM-27 Continuous Tone Electronic Buzzer is a high-output piezoelectric alarm device designed for industrial control panels, security systems, and DIY electronics projects. Built around the HYT-3015B piezo ceramic element, this active buzzer features a built-in oscillator circuit, meaning it produces a continuous, high-pitched tone simply by applying a DC voltage within its operating range — no external PWM signal, tone generator, or driver circuitry is required.

At the heart of the SFM-27 is a piezoelectric ceramic disc bonded to a metal plate. When an oscillating electrical field is applied, the ceramic material stretches and shrinks, causing the metal plate to bend and generate sound waves in the air . The integrated drive circuit handles the oscillation internally, so the buzzer activates immediately upon power-up. The continuous tone output is ideal for sustained alarm conditions, equipment status indication, and attention-grabbing alerts where a steady sound is preferred over an intermittent pattern.

The wide operating voltage range of DC 3V to 24V is a key advantage of this buzzer. It can operate from low-voltage battery packs, 5V USB rails, 12V automotive systems, or 24V industrial control circuits without any adjustment or external regulation . The sound pressure level reaches approximately 85dB to 95dB at 10cm, making it clearly audible in noisy environments such as factory floors, machine shops, and outdoor installations . Current consumption is low at approximately 12mA to 20mA, making it suitable for battery-powered and energy-conscious designs .

The buzzer features a compact cylindrical plastic housing measuring approximately 30mm × 15mm (diameter × height), with pre-attached wire leads for easy connection . The red wire connects to the positive terminal (+) and the black wire to the negative terminal (-) . The white housing provides a clean, professional appearance suitable for panel mounting. Mounting holes are provided for secure installation in equipment enclosures.

The SFM-27 is widely used in industrial control panels, security alarm systems, equipment fault indicators, timers and reminders, home automation, medical devices, automotive warning systems, and educational STEM projects. It is also a popular choice for Arduino and DIY projects where a simple, reliable audible indicator is required.

Important Note: The SFM-27 is an active buzzer — it produces a fixed continuous tone when powered and cannot play melodies or variable frequencies. For intermittent or variable tones, use a passive buzzer with PWM control. When driving directly from a microcontroller GPIO pin, note that the buzzer may draw up to 20mA, which is within the safe continuous current rating of most MCU pins (typically 20mA). For 24V operation, a transistor driver circuit is recommended. The buzzer is not waterproof — avoid exposure to moisture and corrosive environments.

Whether you are building an industrial alarm panel, a security system, or a DIY notification device, the SFM-27 Continuous Tone Electronic Buzzer provides a reliable, high-output solution for audible alerting. It is suitable for individual makers, engineers, and businesses purchasing in bulk for product development or industrial applications.

Features

  • Active buzzer with built-in oscillator — Produces sound directly from DC voltage; no PWM required

  • Wide voltage range — Operates from DC 3V to 24V; compatible with battery, 5V, 12V, and 24V systems

  • Continuous tone output — Steady, high-pitched alarm suitable for sustained alert conditions

  • High sound pressure — 85dB–95dB at 10cm for clear audibility in noisy environments

  • Low current consumption — Approximately 12–20mA, suitable for battery-powered designs

  • Compact 30×15mm package — Standard form factor for panel and equipment mounting

  • Pre-attached wire leads — Red (+) and black (-) wires for simple connection

  • Clear polarity marking — Red wire indicates positive terminal

  • Wide application range — Industrial panels, security alarms, timers, home automation, automotive

  • Cost-effective — Affordable solution for audible indication in volume production

Technical Specifications 

# Parameter Specification
1 Model SFM-27 (HYT-3015B)
2 Buzzer Type Piezoelectric Active Buzzer (built-in oscillator)
3 Operating Voltage DC 3V – 24V
4 Rated Voltage 12V DC
5 Resonant Frequency 3100Hz ± 500Hz
6 Sound Pressure Level 85dB – 95dB @ 10cm
7 Current Consumption ~12–20mA (typical)
8 Package Size Φ30mm × 15mm, wire length ~11cm

Usage

Getting Started

  1. Identify the wires — The red wire is the positive terminal (+) and the black wire is the negative terminal (-) .

  2. Connect power — Apply DC 3V to 24V across the wires (red to positive, black to negative). The buzzer will produce a continuous tone immediately.

  3. Control with a microcontroller — For MCU control, connect the buzzer through a transistor driver circuit (recommended for 12V/24V operation) or directly to a GPIO pin for 3.3V/5V operation if current is limited.

  4. Transistor driver circuit — Connect buzzer positive to VCC, buzzer negative to transistor collector, transistor emitter to GND, and transistor base to MCU GPIO through a resistor (e.g., 1kΩ) .

  5. Upload control code — Set the GPIO pin HIGH to turn the buzzer on, LOW to turn it off.

Wire Connections

Wire Color Function
Red Positive (+) — Connect to VCC (3V–24V)
Black Negative (-) — Connect to GND

Example Arduino Code (Direct GPIO Control)

cpp
#define BUZZER_PIN 8

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

void loop() {
  digitalWrite(BUZZER_PIN, HIGH);  // Buzzer ON
  delay(500);
  digitalWrite(BUZZER_PIN, LOW);   // Buzzer OFF
  delay(500);
}

Transistor Driver Circuit (Recommended for 12V/24V Operation)

Component Connection
Buzzer Red (+) VCC (12V/24V)
Buzzer Black (-) Transistor Collector
Transistor Emitter GND
Transistor Base MCU GPIO via 1kΩ resistor

Typical Applications

  • Industrial control panels — Fault indicators, machine status alerts, process warnings

  • Security alarm systems — Intrusion detection, door/window sensors

  • Equipment fault indicators — Over-temperature, over-voltage, error conditions

  • Timers and reminders — Audible alert when time expires

  • Home automation — Appliance status, doorbell, notification sounds

  • Medical devices — Patient alerts, equipment status indication

  • Automotive warning systems — Parking sensors, dashboard indicators

  • Educational STEM projects — Teaching digital output and sound generation

Notes for Business Buyers

  • Active buzzer — Fixed continuous tone, no PWM required; simple DC voltage drive.

  • Wide voltage tolerance — 3V–24V range supports battery, 5V USB, 12V automotive, and 24V industrial systems.

  • Transistor driver recommended — For 12V/24V operation and MCU control, use a transistor to isolate the buzzer from the MCU.

  • Suitable for bulk purchasing — Ideal for industrial panel builders, security system integrators, and educational institutions.

Q: What is the SFM-27 Continuous Tone Buzzer used for?

It is an active piezoelectric buzzer for producing continuous audible alerts and alarms, used in industrial control panels, security systems, timers, and DIY electronics projects.

Q: What is the difference between SFM-27 Continuous Tone and Intermittent Tone?

The Continuous Tone version produces a steady, uninterrupted sound when powered. The Intermittent Tone version produces a rhythmic on-off beeping pattern. Both are available in the SFM-27 series.

Q: What voltage does the buzzer require?

It operates from DC 3V to 24V, with a rated voltage of 12V DC .

Q: What is the sound output frequency and volume?

The buzzer produces a tone at approximately 3100Hz ± 500Hz with a sound pressure level of 85dB to 95dB at 10cm .

Q: How do I connect the buzzer to power?

Connect the red wire to the positive terminal (+) and the black wire to the negative terminal (-) .

Q: How do I connect the buzzer to an Arduino?

For direct GPIO control (3.3V/5V): connect the red wire to a digital pin and the black wire to GND. For 12V/24V operation, use a transistor driver to isolate the buzzer from the MCU .

Q: Why does my buzzer only click instead of producing a continuous tone?

You may be using the Arduino tone() function, which is designed for passive buzzers. For active buzzers like the SFM-27, use digitalWrite(pin, HIGH) to supply steady DC voltage instead.

Q: Is the buzzer waterproof?

No. The SFM-27 is not waterproof and should be kept dry. Avoid exposure to moisture and corrosive environments.

Q: Can I play different tones or melodies with this buzzer?

No. The SFM-27 is an active buzzer with a fixed continuous tone. It cannot play melodies or variable frequencies. For variable tones, use a passive buzzer with PWM.

Q: Can I purchase in bulk for a product development project?

Yes. The SFM-27 is suitable for bulk purchasing by industrial panel builders, security system integrators, and educational institutions.

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