Product Overview：
A Passive Piezoelectric Buzzer is an electroacoustic device without a built-in oscillation circuit. It relies on an external controller (MCU, Single-Chip Microcomputer, PWM signal source) to provide a square wave/pulse signal of a specific frequency, which causes the internal piezoelectric ceramic chip to vibrate and produce sound.
Features:
- ✅ Passive Drive: No built-in oscillation; external frequency supply is required (2kHz–4kHz is optimal)
- ✅ Adjustable Frequency: The tone can be changed by adjusting the input square wave frequency, supporting multiple sound effects
- ✅ Low power consumption, small size, long service life and high reliability
- ✅ Non-polar or weakly polar design, flexible installation
- Application Scenarios: Home appliance control panels, alarms, timers, instruments and meters, smart home, medical equipment, vehicle prompt sounds, etc.
Brief Working Principle
The internal core consists of a piezoelectric ceramic chip + resonance cavity:
- External input of alternating voltage/square wave → ceramic chip expands and contracts to vibrate → air vibrates to produce sound
- It must match theresonant frequency of the buzzer (usually around 4kHz); otherwise, the sound will be weak, distorted or inaudible
Electrical and Driving Requirements
- Driving Signal: Square wave PWM, with a duty cycle of 20%–50% for optimal effect
- Frequency Range: Recommended 3kHz–4kHz (subject to the nominal resonant frequency of the model)
- Operating Current: Piezoelectric type is generally ≤10mA, with low power consumption
- Polarity Description: Most passive piezoelectric buzzers have no strict positive or negative polarity; if there is a mark, it is recommended to wire according to the mark for better consistency
Recommended Key Models of Passive Piezoelectric Buzzers from Jiangsu Huaneng Electronics：
HNR-1407：
- Size: φ14 × 7mm
- Resonant Frequency: 4kHz
- Operating Voltage: 3–12V
- Sound Pressure: ≥75dB
- Features: Standard round pin, universal package, cost-effective
- Recommendation: Small home appliances, remote controls, alarms, ordinary instruments
HNR-4216：
- Size: φ22 × 16mm (4216 is the industry standard designation)
- Frequency: 3kHz
- Voltage: 5–24V
- Sound Pressure: ≥85–90dB, strong penetration
- Features: Large sound cavity, high loudness, suitable for long-distance/noisy environments
- Recommendation: Industrial alarms, security systems, equipment fault alarms, outdoor equipment
HNR-4016：
- Size: φ20 × 16mm
- Frequency: 3kHz (Typical)
- Voltage: 5–18V
- Sound Pressure: ≥82dB
- Features: Moderate size, balanced volume and power consumption, strong versatility
- Recommendation: Building intercom, smart home, large home appliances, control cabinets
