The **BH3N-R** is a specific model of a **Piezoelectric Diaphragm (Buzzer)** typically manufactured by companies like BeStar. These components are used to convert electrical signals into sound. --- ### 1. Key Electronic Specifications The "R" suffix often indicates compliance with environmental standards (RoHS) or a specific lead configuration. Below are the typical electronic characteristics for this series: | Parameter | Specification (Typical) | | :--- | :--- | | **Resonant Frequency** | 3.0 kHz ± 0.5 kHz | | **Resonant Resistance** | 200 Ω to 500 Ω (Max) | | **Capacitance** | 20,000 pF to 30,000 pF (at 120Hz) | | **Input Voltage** | 30 Vp-p (Maximum) | | **Operating Temperature** | -20°C to +70°C | --- ### 2. Physical Construction The BH3N-R consists of several layers that work together to create sound through the **Inverse Piezoelectric Effect**: 1. **Piezoelectric Ceramic:** A thin layer of Lead Zirconate Titanate (PZT) that expands or contracts when an electric field is applied. 2. **Metal Plate (Diaphragm):** Usually made of brass or stainless steel. The ceramic is bonded to this plate. When the ceramic moves, it forces the metal plate to flex, pushing air to create sound waves. 3. **Electrodes:** Silver or thin metal coatings on the ceramic surface to allow for wire attachment (usually via soldering). --- ### 3. Circuit Integration Since the BH3N-R is a **passive** piezoelectric element, it does not have a built-in drive circuit. To use it, you must provide an external oscillating signal. #### Common Drive Methods: * **Transistor Switching:** Using a NPN transistor to pulse the piezo at its resonant frequency. * **H-Bridge:** For higher volume, an H-bridge can double the effective voltage across the piezo. * **Microcontroller (PWM):** Directly driving via a GPIO pin (often requiring a current-limiting resistor and a flyback diode to protect the MCU from voltage spikes). ```cpp // Example: Driving a BH3N-R with an Arduino/ESP32 int buzzerPin = 9; void setup() { pinMode(buzzerPin, OUTPUT); } void loop() { // Generate a 3kHz tone (the resonant frequency of BH3N-R) tone(buzzerPin, 3000); delay(500); noTone(buzzerPin); delay(500); } ``` --- ### 4. Application Areas * **Home Appliances:** Beeps for microwave ovens, washing machines, and timers. * **Alarms:** Smoke detectors or low-battery indicators. * **Consumer Electronics:** Confirmation tones in calculators or handheld devices.