The **M2BD-081-R/UL** is a high-performance **Magnetic Buzzer (Transducer)** manufactured by components brands like Mallory Sonalert or similar electronic suppliers. This part is specifically designed for integration into PCB layouts where a loud, reliable acoustic signal is required in a small footprint. --- ### Technical Specifications Below are the primary electronic and mechanical characteristics of the M2BD-081-R/UL: | Characteristic | Specification | | :--- | :--- | | **Type** | Magnetic Transducer (Requires external drive circuit) | | **Operating Voltage** | 1.0V ~ 2.0V DC (Typical 1.5V) | | **Current Consumption** | Max 10mA - 30mA (depending on drive frequency) | | **Resonant Frequency** | 2,048 Hz (Standard tone) | | **Sound Pressure Level (SPL)** | ≥ 80 dB @ 10cm | | **Operating Temperature** | -20°C to +70°C | | **Mounting Type** | Through-hole (PCB Mount) | | **Termination** | PC Pins | --- ### Key Electronic Features #### 1. Magnetic Transducer Principle Unlike a "piezo" buzzer that uses ceramic crystals, this is a **magnetic** device. It consists of a permanent magnet, a wire coil, and a vibrating metal diaphragm. When an oscillating current passes through the coil, it creates a fluctuating magnetic field that moves the diaphragm to produce sound. #### 2. External Drive Requirement The "Transducer" designation means it **does not** have internal circuitry to generate a tone. * You cannot simply apply a DC voltage to it. * It requires an **AC signal or square wave** (usually 2,048 Hz) from a microcontroller (MCU) or a 555 timer circuit. #### 3. UL Compliance The "UL" suffix indicates that the component meets **Underwriters Laboratories** safety standards for flame retardancy and electrical safety, making it suitable for industrial and consumer appliances. --- ### Example Drive Circuit To use this part with a 3.3V or 5V microcontroller, a simple transistor switching circuit is recommended to handle the current: ```cpp // Logic Diagram [MCU GPIO] ---> [1k Ohm Resistor] ---> [Base of NPN Transistor (e.g., 2N2222)] // Connections: // Transistor Collector -> Buzzer (-) Pin // Buzzer (+) Pin -> 1.5V Power Supply // Transistor Emitter -> Ground ``` --- ### Typical Applications * **Medical Equipment:** Heart rate monitors or alarm indicators. * **Consumer Electronics:** Microwave beepers, timers, and clocks. * **Industrial:** Control panel feedback and error signaling. ---