The **PMS-G-R** is a specific variant of a **Miniature Pressure Sensor** (often referred to as a Pressure Transducer), typically manufactured by companies like **Kyowa** or similar precision instrument firms. This sensor is designed to measure gaseous or liquid pressure in extremely confined spaces. Below is an explanation of its electronic components and characteristics. --- ## 1. Electronic Composition The PMS-G-R operates based on **Bonded Strain Gauge** technology. | Component | Description | | :--- | :--- | | **Sensing Element** | A metallic diaphragm that deforms under pressure. | | **Strain Gauges** | High-sensitivity resistors bonded to the diaphragm. They convert mechanical strain into electrical resistance change. | | **Wheatstone Bridge** | The internal circuit configuration (usually a full bridge) used to output a voltage proportional to the pressure. | | **Compensation Circuit** | Internal resistors used for zero-point and span thermal compensation. | --- ## 2. Technical Specifications The "G" in the name generally denotes **Gauge Pressure**, and "R" often refers to a specific **Rated Capacity** or a refined design iteration. ### Electrical Characteristics * **Bridge Resistance:** Typically **350Ω** (Standard for industrial strain gauges). * **Excitation Voltage:** Usually **2V to 5V AC/DC** (Recommended), Max 10V. * **Rated Output:** Approximately **1.0 mV/V to 2.0 mV/V** (at full scale). * **Insulation Resistance:** $>500 M\Omega$ at 50V DC. --- ## 3. Wiring and Connection The PMS-G-R usually features a 4-wire lead system. These leads must be connected to a signal conditioner or an amplifier (like a strain amplifier) to convert the millivolt signal into a readable format. ### Color Coding (Standard) | Wire Color | Function | | :--- | :--- | | **Red** | Input / Excitation (+) | | **Black** | Input / Excitation (-) | | **Green** | Output / Signal (+) | | **White** | Output / Signal (-) | --- ## 4. Key Features for Electronics Designers 1. **Miniaturization:** These sensors are typically extremely small (often 4mm to 6mm in diameter), making them ideal for wind tunnel testing, pipe internal measurements, or biomedical applications. 2. **High Frequency Response:** Due to the small diaphragm mass, they can measure rapid pressure fluctuations. 3. **Low Power Consumption:** Since they are purely resistive (passive), they draw very little current, dictated by Ohm’s Law ($I = V/R$). --- ## 5. Usage Precautions * **Signal Amplification:** Because the output is in millivolts, you must use a high-precision Instrumentation Amplifier (e.g., AD620 or similar) to interface with a microcontroller (like an Arduino or ESP32). * **Excitation Stability:** The output is directly proportional to the input voltage. If the power supply fluctuates, the pressure reading will drift. Use a stable LDO or reference voltage.