The **APTE-5122-R** is a high-performance, surface-mount (SMT) piezoelectric transducer designed primarily for audio signaling in compact electronic devices. It is manufactured by brands like **Mallory Sonalert Products**. --- ### 1. Technical Specifications The following table summarizes the core electronic and physical characteristics of the APTE-5122-R: | Parameter | Specification | | :--- | :--- | | **Technology** | Piezoelectric (External Drive) | | **Sound Pressure Level (SPL)** | 80 dB @ 10cm | | **Rated Voltage** | 3.0 Vp-p (Square Wave) | | **Operating Voltage Range** | 1.0 ~ 25.0 Vp-p | | **Resonant Frequency** | 4000 ± 500 Hz | | **Capacitance** | 12,000 pF ± 30% @ 120Hz | | **Mounting Type** | Surface Mount (SMT) | | **Current Consumption** | 3 mA (Max) | --- ### 2. Key Electronic Components & Design The device is an **External Drive** transducer, meaning it does not contain an internal oscillation circuit. To function, it requires an external AC signal (usually a square wave). * **Piezoelectric Element:** Consists of a ceramic disc bonded to a metal diaphragm. When a voltage is applied, the ceramic deforms, causing the diaphragm to vibrate and create sound waves. * **Housing:** High-temperature plastic (LCP - Liquid Crystal Polymer) designed to withstand lead-free reflow soldering processes. * **Electrodes:** Silver or gold-plated pads on the bottom of the unit for SMT integration. --- ### 3. Application Circuit Example Because it is an external drive type, it is often driven by a microcontroller (MCU) through a transistor or a MOSFET to handle the voltage peaks. ```cpp // Example: Driving a Piezo at Resonant Frequency (4kHz) void setup() { pinMode(9, OUTPUT); // Connect to Transistor driving the APTE-5122-R } void loop() { tone(9, 4000); // Generate 4kHz square wave delay(500); // Beep for 0.5s noTone(9); // Silence delay(500); } ``` --- ### 4. Comparison with Magnetic Buzzers The APTE-5122-R (Piezo) differs significantly from magnetic buzzers: 1. **Current Draw:** Piezos like the 5122-R use very little current (3mA) compared to magnetic buzzers (30mA+). 2. **Voltage:** It can handle much higher peak-to-peak voltages (up to 25V) for louder output. 3. **Frequency:** It is optimized for a high pitch (4kHz), which is very "piercing" and good for alarms.