The **47DR-112A-R** is a specific model of an **Electromagnetic Buzzer** (also known as a magnetic transducer). These components are widely used in consumer electronics, automotive systems, and industrial equipment to provide audible feedback. Below is a detailed breakdown of its electronic characteristics and specifications. --- ### 1. General Specifications The "47DR" series typically follows standard industry specifications for high-output magnetic buzzers. | Parameter | Typical Value | | :--- | :--- | | **Type** | Electromagnetic / Magnetic Transducer | | **Drive Type** | External Drive (requires an oscillating circuit) | | **Rated Voltage** | 1.5V - 3.0V DC | | **Operating Voltage** | 1.0V ~ 5.0V DC | | **Rated Current** | Max 70mA - 80mA | | **Sound Pressure Level (SPL)** | Min 85dB at 10cm | | **Resonant Frequency** | 2000Hz - 2700Hz | | **Operating Temperature** | -20°C to +70°C | --- ### 2. Internal Construction As an electromagnetic buzzer, the 47DR-112A-R consists of several key internal parts: 1. **Voice Coil:** A winding of fine copper wire that generates a magnetic field when current passes through it. 2. **Permanent Magnet:** Provides a static magnetic field that interacts with the coil. 3. **Vibrating Diaphragm:** A thin metal disk (usually iron or steel) that is physically moved by the magnetic forces to create sound waves. 4. **Housing:** A plastic casing (usually NORYL or PBT) designed to act as an acoustic resonance chamber. --- ### 3. Circuit Integration Unlike "indicators" which beep as soon as power is applied, this part is a **transducer**. This means it requires a square wave signal from a microcontroller (MCU) or a 555-timer circuit to function. #### Sample Driving Circuit To drive this component using an MCU pin, a transistor is generally required because the current draw (approx. 80mA) exceeds the capacity of most GPIO pins. ```c // Example: Driving logic via NPN Transistor [MCU PIN] --- [Resistor] --- [Base of NPN Transistor] | [Buzzer 47DR] --- [VCC] | [GND] ``` --- ### 4. Key Features & Applications * **Washable/Sealed:** The "R" or specific suffixes in this series often denote a sealed design, allowing the part to be wave-soldered and washed without damaging the internal diaphragm. * **Small Footprint:** Designed for PCB mounting (through-hole). * **Applications:** * Microwave ovens and kitchen appliances. * Handheld glucose meters or medical devices. * Computer motherboards (POST code beeps). * Security alarm panels.