Piezoelectric sounder

01

Choose indicator or transducer, and the loudness at distance

Same Sky's buzzer guide explains that a piezo buzzer has electrodes on both faces of a piezoelectric disc supported at its edges; applying a voltage deforms the disc and makes sound. It divides buzzers into indicators, which have the drive circuit built in and sound at a fixed frequency when a DC voltage is applied, and transducers, which need an external drive signal such as a square wave but can produce multiple tones — high/low, siren and chime. [1]

The guide defines sound pressure level as the deviation from atmospheric pressure caused by the sound wave, and says it is proportional to input voltage and decays by 6 dB when the distance from the buzzer doubles. It defines resonant frequency as the frequency at which the buzzer is loudest, and contrasts piezo buzzers (12–220 V, under 20 mA) with magnetic buzzers (1.5–12 V, over 20 mA). [1]

Same Sky's CPT-1207-3TH piezo transducer lists 75 dB at 10 cm at 3 Vp-p and 4,000 Hz with a half-duty square wave, and its CPI-3119-90PM panel-mount piezo indicator lists 90 dB at 30 cm at 12 Vdc, with a 2,600–3,600 Hz rated frequency. [2] [3]

Editorial calculation: by the 6 dB-per-doubling rule, 75 dB at 10 cm is about 65.5 dB at 30 cm (75 − 20·log₁₀3), and 90 dB at 30 cm is about 84 dB at 60 cm and 78 dB at 1.2 m. Compare sounders only at the same distance and drive. [1] [2] [3]

Give the supplier the type (indicator or transducer), tone (continuous, pulsed, multi-tone), SPL required at a stated distance, frequency, rated and operating voltage, maximum current, mounting (PCB through-hole, SMD, panel, wire leads), size limits, housing material, operating temperature, sealing or wash requirements, and quantity.

02

Match drive voltage, current, capacitance and mounting

The guide says a piezo buzzer is driven by voltage rather than current and is modelled as a capacitor; its output is reasonably linear with drive signal strength. A transducer can be driven by a switch with a resistor to reset the voltage, but a full-bridge driver doubles the peak-to-peak voltage across the transducer and raises sound output by about 6 dB. Some piezo buzzers include a feedback electrode that simplifies the drive circuit. [1]

The CPT-1207-3TH lists 3 Vp-p rated and 30 Vp-p maximum operating voltage, 3 mA at rated voltage, 8,400–15,600 pF capacitance at 100 Hz, Ø12.5 × 7.0 mm size, 0.8 g, black PPO housing, through-hole pins, −40 to 85 °C operation, and is not washable. [2] The CPI-3119-90PM lists 3–20 Vdc operating range, 15 mA at 12 Vdc, Ø33 × 19.4 mm, 2.5 g, PBT housing, wire leads and −30 to 70 °C operation. [3]

Linked suppliers list SMD piezo buzzers from 70 to 75 dB at 3–5 Vp-p and 4–5.2 kHz [4], 12 Vdc and 24 Vdc piezo buzzers rated 85 dB [5], and piezo alarms and sirens for security and safety. [6]

03

Compare what suppliers offer

Suppliers linked to this page list piezo buzzers and sounders; each card links to the page reviewed.

The listings reviewed range from SMD and through-hole piezo transducers to DC piezo indicators and piezo sirens and alarms. Ask each for SPL with its measuring distance and drive, frequency tolerance, current and operating temperature. [4] [5] [6] [7] [8]

04

Trace what each part controls

This is a functional reference built from the sources cited; it is not one maker's specification.

05

Fill the specification fields with values for your device

A piezo sounder quotation needs values for your device. The table explains each field, gives published values where a reviewed source states them, and says what to obtain from the supplier.

06

Send the type, loudness and drive data together

Paste it into your enquiry below or into an email to a maker, then replace every bracket.

Type: [indicator; transducer]
Tone: [continuous; pulse; multi-tone]
SPL: [dB at cm]
Frequency: [Hz]
Supply: [V; max mA]
Mounting: [THT; SMD; panel; leads]
Environment: [°C; sealing]
Quantity: [units]

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