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

SKU: FA3048-5-1
Model

SFM-27 (HYT-3015B)
Buzzer Type

Piezoelectric Active Buzzer (built-in oscillator)
Sound Pattern

Continuous
Operating Voltage

DC 3V – 24V
Rated Voltage

12V DC
Resonant Frequency

3100Hz ± 500Hz
Sound Pressure Level

85dB – 95dB @ 10cm
Package Size

Φ30mm × 15mm, wire length ~11cm

The SFM-27 Continuous Tone Electronic Buzzer (Black) 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 black 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 (Black) 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

  • Black housing — Clean, professional appearance for panel mounting

  • 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 Sound Pattern Continuous
4 Operating Voltage DC 3V – 24V
5 Rated Voltage 12V DC
6 Resonant Frequency 3100Hz ± 500Hz
7 Sound Pressure Level 85dB – 95dB @ 10cm
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 the Continuous and Intermittent tone versions?

The Continuous version produces a steady, uninterrupted sound. The Intermittent version produces a rhythmic beep-beep-beep pulsing 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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