The **LSMT2-42040-R** is an ultra-miniature, surface-mount (SMT) magnetic transducer (buzzer) commonly used in small consumer electronics for providing audible alerts or notifications. --- ### ## Technical Specifications Below is a breakdown of the typical electronic characteristics for this specific part: | Parameter | Value/Range | | :--- | :--- | | **Rated Voltage** | 3.6 Vp-p | | **Operating Voltage** | 2.5 ~ 4.5 Vp-p | | **Rated Current** | Max 100 mA | | **Coil Resistance** | 15 ± 3 Ω | | **Sound Pressure Level (SPL)** | Min 85 dB (at 10cm) | | **Resonant Frequency** | 2,700 Hz | | **Operating Temperature** | -30°C to +70°C | | **Mounting Type** | Surface Mount (SMT) | --- ### ### Key Electronic Components & Working Principle 1. **Magnetic Coil**: The core component is a wire coil with a resistance of approximately 15 Ohms. When an alternating current (AC) or pulsed DC signal passes through it, it creates a fluctuating magnetic field. 2. **Permanent Magnet**: Inside the housing, a permanent magnet provides a static magnetic field that interacts with the field produced by the coil. 3. **Vibrating Diaphragm**: A metal disk (usually iron or a magnetic alloy) is attracted and released rapidly by the magnetic fluctuations, causing it to vibrate at the input frequency and push air to create sound. 4. **Passive Nature**: This is a **transducer**, not an indicator. It does *not* have internal circuitry to generate sound. It requires an external oscillating signal (PWM) at its resonant frequency (2,700 Hz) to function. --- ### ### Application Circuitry To drive this component using a microcontroller (like an Arduino or ESP32), you typically need a transistor switching circuit because the current draw (100mA) is higher than what a standard GPIO pin can provide. ```cpp // Example: Generating a 2.7kHz tone on a GPIO pin int buzzerPin = 9; void setup() { pinMode(buzzerPin, OUTPUT); } void loop() { tone(buzzerPin, 2700); // Send 2.7kHz square wave delay(500); noTone(buzzerPin); delay(1000); } ``` --- ### ### Design Considerations * **Polarity**: This part is polarized. The "+" mark on the casing must be connected to the positive side of your driving signal. * **Reflow Soldering**: As an SMT component, it is designed to withstand standard lead-free reflow soldering profiles, but overheating can damage the internal magnets or plastic housing. * **Acoustic Hole**: Ensure the hole on the top of the buzzer is not obstructed by the product casing or labels, as this will significantly muffle the sound.