## POM-2738P-R: Electret Condenser Microphone The **POM-2738P-R** is a high-sensitivity, omnidirectional electret condenser microphone (ECM) manufactured by PUI Audio. It is designed for general-purpose audio recording and sensing applications where a small footprint and reliable performance are required. --- ### 1. Key Technical Specifications Below are the primary electrical and physical characteristics of the POM-2738P-R: | Parameter | Specification | | :--- | :--- | | **Directivity** | Omnidirectional | | **Sensitivity** | -38 ± 3 dB (0dB=1V/Pa, 1kHz) | | **Rated Voltage** | 2.0 V | | **Operating Voltage Range** | 1.5 V to 10 V | | **Current Consumption** | Max 0.5 mA | | **Frequency Range** | 20 Hz to 20,000 Hz | | **Signal-to-Noise Ratio** | > 60 dB | | **Impedance** | 2.2 kΩ | | **Dimensions** | Ø 6.0 mm x 2.7 mm | | **Mounting Type** | Through-hole (Solder Pads/Pins) | --- ### 2. Functional Principles * **Electret Diaphragm:** The device uses a permanently polarized material (electret) that eliminates the need for a high-voltage external power supply for the capsule itself. * **Built-in FET:** It contains an internal Field Effect Transistor (FET). Since the diaphragm produces a very high impedance signal, the FET acts as an impedance converter, allowing the signal to be transmitted over wires without significant loss or noise. * **Omnidirectional Polar Pattern:** It picks up sound equally from all directions. This makes it ideal for ambient noise sensing or situations where the microphone's orientation to the sound source might change. --- ### 3. Application Circuitry To use the POM-2738P-R, a simple biasing circuit is required. The microphone acts as a variable current sink. ```mermaid [Vcc (+2.0V)] | [RL (2.2kΩ Resistor)] | +----[C (Output Capacitor 0.1uF - 1uF)]----> Audio Out | [POM-2738P-R (+)] [POM-2738P-R (-)] | [GND] ``` * **RL (Load Resistor):** Typically 2.2kΩ. It determines the gain and operating current. * **C (Coupling Capacitor):** Blocks the DC bias voltage from entering the following amplifier stage, allowing only the AC audio signal through. --- ### 4. Common Applications * **Consumer Electronics:** Telephones, laptops, and voice recorders. * **Industrial:** Noise monitoring systems and security sensors. * **IoT Devices:** Voice-activated assistants and smart home sensors. * **DIY Electronics:** Arduino or Raspberry Pi audio input modules (requires a pre-amplifier).