The **SCT013-RJ45** is a variation of the popular SCT013 non-invasive Current Transformer (CT) sensor. While the standard SCT013 typically uses a 3.5mm audio jack, this specific model utilizes an **RJ45 connector** (Ethernet style) for more secure industrial connectivity and easier integration into structured cabling systems. --- ## 1. Technical Specifications The core electronic components consist of a ferrite core and a secondary winding that follows the principle of electromagnetic induction. | Feature | Specification (Typical) | | :--- | :--- | | **Input Current** | 0A - 100A AC (depending on sub-model) | | **Output Type** | 0-50mA (Current output) or 0-1V (Voltage output) | | **Core Material** | Ferrite | | **Accuracy** | ±1% | | **Linearity** | ≤0.2% | | **Connector** | RJ45 | | **Lead Length** | 1 meter - 1.5 meters | --- ## 2. Electronic Components & Internal Design ### A. The Ferrite Core (Transformer) The "split-core" design allows the sensor to open and snap around a live wire without cutting the circuit. The ferrite core concentrates the magnetic field generated by the AC current passing through the primary wire. ### B. Secondary Winding Inside the plastic housing, a copper wire is coiled around the core many times. This converts the high primary current (e.g., 100A) into a small, measurable signal (e.g., 50mA) based on the turns ratio. ### C. The Burden Resistor * **Current Output Version:** Does NOT have an internal resistor. You must add an external burden resistor to convert current to voltage for a microcontroller. * **Voltage Output Version:** Includes an internal precision **Burden Resistor**. This allows the sensor to output a safe 0-1V signal directly. --- ## 3. RJ45 Pinout Configuration Unlike standard Ethernet data cables, the RJ45 on an SCT013 sensor usually only utilizes 2 pins. While manufacturers may vary, the standard mapping is often: | RJ45 Pin | Function | | :--- | :--- | | **Pin 1 / Pin 2** | Signal Output (+) / (-) | | **Other Pins** | Usually Not Connected (NC) | > **Warning:** Never plug an SCT013-RJ45 directly into a computer's Ethernet port or a Network Switch, as the voltage spikes could damage the hardware. --- ## 4. Basic Interface Circuit (For Arduino/ESP32) Since microcontrollers cannot measure negative AC voltages, you must use a "DC Bias" circuit to shift the signal into a readable range (e.g., 2.5V center for a 5V system). ```cpp // Basic Calculation Example for SCT013 double getAmps(int pinValue) { double voltage = (pinValue * 5.0) / 1024.0; // Convert ADC to Voltage double current = voltage * calibrationFactor; // Apply calibration return current; } ``` ---