The **47LM-141B-R** is a specific model of an **Electromagnetic Buzzer** (specifically a magnetic transducer). These components are widely used in consumer electronics, automotive alerts, and industrial equipment to provide audible feedback. --- ### 1. Key Technical Specifications The following table summarizes the typical electronic characteristics of the 47LM-141B-R series: | Parameter | Specification | | :--- | :--- | | **Type** | Magnetic Transducer (External Drive) | | **Rated Voltage** | 1.5V to 5.0V (Model dependent) | | **Operating Voltage** | 1.0V ~ 7.0V | | **Rated Current** | Max 40mA ~ 80mA | | **Sound Pressure Level (SPL)** | Min 85dB (at 10cm) | | **Resonant Frequency** | 2,400Hz to 2,700Hz | | **Coil Resistance** | 42Ω ± 5Ω (Standard) | | **Operating Temperature** | -30°C to +70°C | --- ### 2. Physical Construction The part is designed for PCB (Printed Circuit Board) mounting. Key physical features include: * **Housing:** High-temperature plastic (usually PBT or PPS) capable of withstanding wave soldering. * **Terminals:** Through-hole pins (R suffix often denotes Radial or specific Pin spacing). * **Dimensions:** Typically circular with a diameter of ~12mm and a height of ~9.5mm. * **Sound Port:** Top-opening hole for sound emission. --- ### 3. Operating Principle Unlike a "piezo" buzzer which uses ceramic expansion, the **47LM-141B-R** is an electromagnetic device: 1. **Electromagnetism:** An internal coil is wrapped around a core. 2. **Vibration:** When an oscillating current (square wave) is applied, it creates a fluctuating magnetic field. 3. **Diaphragm:** A metal disk (diaphragm) is attracted and released by the magnetic field, vibrating at the input frequency to create sound waves. --- ### 4. Implementation Circuitry Because this is a **transducer** (not an indicator), it does not have an internal oscillating circuit. You must provide a square wave at the resonant frequency to make it sound. ```cpp // Example Arduino-style pseudo-code to drive the part void setup() { pinMode(BUZZER_PIN, OUTPUT); } void loop() { // Generate a 2400Hz square wave tone(BUZZER_PIN, 2400); delay(500); noTone(BUZZER_PIN); delay(500); } ``` --- ### 5. Common Applications * **Appliances:** Microwave "beeps," washing machine cycle alerts. * **Computing:** Motherboard POST codes (BIOS beeps). * **Medical:** Heart rate monitors or alarm indicators. * **Handheld Devices:** POS terminals and barcode scanners.