### Technical Overview of SMT-0824-SW-3V-R The **SMT-0824-SW-3V-R** is a high-performance, surface-mount (SMT) magnetic transducer manufactured by **PUI Audio**. It is designed for compact electronic devices requiring audible alerts or feedback. --- ### 1. Key Technical Specifications | Parameter | Specification | | :--- | :--- | | **Type** | Magnetic Transducer (External Drive) | | **Rated Voltage** | 3 Vp-p | | **Operating Voltage Range** | 2 ~ 4 Vp-p | | **Rated Current (Max)** | 80 mA | | **Sound Pressure Level (SPL)** | 85 dBA @ 10cm | | **Resonant Frequency** | 2,400 Hz | | **Coil Resistance** | $15 \pm 3 \Omega$ | | **Mounting Type** | Surface Mount (SMT) | | **Dimensions** | 8.5mm x 8.5mm x 4.0mm | --- ### 2. Functional Components As a **magnetic transducer**, this part consists of several internal electronic and mechanical components: 1. **Voice Coil:** A small coil of wire that generates a magnetic field when an alternating current (AC) or square wave passes through it. 2. **Permanent Magnet:** Provides a static magnetic field that interacts with the coil's field. 3. **Diaphragm:** A thin metal or plastic plate attached to the assembly. The magnetic interaction causes this diaphragm to vibrate at the frequency of the input signal. 4. **Housing:** A High-Temperature Plastic (LCP) casing designed to withstand reflow soldering temperatures. --- ### 3. Application & Circuit Requirements Unlike an "indicator" (which has internal circuitry to beep when DC power is applied), this is a **transducer**. This means: * **External Drive Required:** You must provide a square wave signal (typically 2,400 Hz) to the device. * **Driver Circuitry:** It is usually driven by a microcontroller (MCU) through a transistor (BJT or MOSFET) to provide the necessary current (80mA), as most MCU pins cannot handle that load directly. * **Polarity:** The device is polarized; ensure the positive terminal is connected correctly to the driving circuit. --- ### 4. Circuit Example (Simplified) ```text VCC (3V) | [ Buzzer ] | [ Collector ] MCU --[ Base ] (NPN Transistor) [ Emitter ] | GND ``` ---