The **47LM-140R-R** is a specific part number typically associated with **Electromagnetic Buzzers** or **Magnetic Transducers**, often manufactured by companies like *LXD* or *Kingstate*. These components are designed to convert electrical signals into audible sound through magnetic oscillation. --- ### 1. Technical Specifications Below are the typical specifications for the 47LM series magnetic transducers: | Parameter | Typical Value | | :--- | :--- | | **Type** | Magnetic / Electromagnetic | | **Rated Voltage** | 1.5V - 12V DC (Model dependent) | | **Operating Voltage** | 1.0 ~ 15V DC | | **Current Consumption** | Max 40mA - 80mA | | **Sound Pressure Level (SPL)** | Min 85dB at 10cm | | **Resonant Frequency** | 2400Hz - 2700Hz | | **Operating Temperature** | -20°C to +70°C | | **Mounting Type** | Through-hole (DIP) | --- ### 2. Physical Construction The part is generally composed of the following internal elements: 1. **Permanent Magnet:** Provides a static magnetic field. 2. **Electromagnet (Coil):** When current flows through the coil, it creates a fluctuating magnetic field. 3. **Vibrating Diaphragm:** A metal disk that is attracted and released by the magnetic field, creating sound waves. 4. **Housing:** Usually a Black PBT (Polybutylene Terephthalate) plastic casing that acts as an acoustic chamber. --- ### 3. Key Features * **External Drive:** Unlike "indicators" that beep as soon as power is applied, this "transducer" requires an external square wave signal (PWM) to function. * **High Reliability:** No moving contacts (unlike mechanical buzzers), leading to a longer lifespan. * **Compact Design:** The "140" in the series often refers to a specific diameter or height (e.g., 14mm). * **RoHS Compliant:** The "-R" suffix usually denotes compliance with RoHS environmental standards. --- ### 4. Circuit Implementation To drive the 47LM-140R-R using a microcontroller (like an Arduino or ESP32), you should use a transistor to handle the current draw. ```cpp // Example: Generating a 2.4kHz tone on Pin 9 void setup() { pinMode(9, OUTPUT); } void loop() { tone(9, 2400); // Send square wave to the buzzer delay(500); noTone(9); // Silence delay(500); } ``` --- ### 5. Common Applications * **Household Appliances:** Microwave beeps, washing machine cycle ends. * **Industrial Equipment:** Error alarms or status indicators. * **Medical Devices:** Pulse monitors or alert systems. * **Computer Peripherals:** Motherboard "POST" code beepers.