The **FST7** usually refers to the **FST7 series of pressure sensors/transmitters** (specifically the FST700 or similar industrial models produced by manufacturers like Firstrate). These devices are designed to convert physical pressure into an electrical signal for industrial automation. Below is an explanation of the electronic components and internal structure of these parts. --- ### 1. Internal Electronic Architecture The FST7 series utilizes a combination of mechanical sensing and solid-state electronics to ensure accuracy. | Component | Description | Function | | :--- | :--- | :--- | | **Sensing Element** | High-precision silicon piezoresistive chip | Detects physical pressure changes via the Wheatstone bridge principle. | | **ASIC Chip** | Application-Specific Integrated Circuit | Performs signal amplification, temperature compensation, and linear calibration. | | **Protection Circuit** | TVS (Transient Voltage Suppressors) | Protects the internal electronics from power surges and reverse polarity. | | **Output Module** | Current/Voltage Driver | Converts the processed signal into standard industrial outputs (e.g., 4-20mA). | --- ### 2. Technical Specifications The electronics are designed to operate in harsh environments with the following typical parameters: * **Supply Voltage:** Usually 9V – 30V DC. * **Output Signal:** * **Current:** 4-20mA (Standard two-wire). * **Voltage:** 0-5V or 0-10V. * **Insulation Resistance:** >100MΩ/50V. * **EMC Protection:** Built-in anti-interference filters to prevent signal noise from nearby motors or machinery. --- ### 3. Wiring Configuration Depending on the output type, the electronic connection usually follows one of two schemes: #### A. Two-Wire System (4-20mA) 1. **Red Wire:** Positive Power Supply ($V+$). 2. **Blue/Black Wire:** Signal Output ($I_{out}$ / Ground). #### B. Three-Wire System (Voltage) 1. **Red Wire:** Positive Power Supply ($V+$). 2. **Black Wire:** Common Ground (GND). 3. **Yellow/White Wire:** Voltage Signal Output ($V_{out}$). --- ### 4. Key Features of the Electronics * **Digital Temperature Compensation:** The internal microprocessor adjusts for errors caused by heat, ensuring stability from -20°C to +85°C. * **Encapsulation:** The electronics are often potted in epoxy resin within a stainless steel housing to prevent damage from vibration and moisture (IP65/IP67 rating). * **Long-term Stability:** High-grade capacitors and resistors are used to minimize "drift" over years of continuous operation. ---