SCT-013 sensor adapter

Essential interface module designed to connect SCT-013 current transformers to microcontrollers like ESP32. This adapter provides complete signal conditioning circuit with precision voltage divider and filtering, converting the transformer's AC output to a microcontroller-friendly 0-3.3V signal. Engineered for seamless integration with RBgrid SDK and RBgrid App.

Connection Guide: https://www.rbgrid.io/application-hardware-connection

Technical Specifications

Electrical Characteristics:

• Input: 3.5mm stereo jack socket for SCT-013
• Supply voltage: 3.3V DC
• Output signal: 0-3.3V (centered at 1.65V)

Connection to ESP32:

Adapter Pin  →  ESP32 Pin
-----------     ----------
GND         →   GND
VCC         →   3.3V
SIG         →   GPIO32/33/34/35/36/39 (ADC1 pins)

Circuit Functionality

Signal Path:

1. AC Input - CT secondary current/voltage via 3.5mm jack
2. Voltage Divider - Creates 1.65V DC bias point
3. AC Coupling - Superimposes AC signal on DC bias
4. Filtering - Capacitor smooths high-frequency noise
5. Output - Clean 0-3.3V signal for ADC reading

Technical Advantages

• Plug-and-Play - No external components needed
• Optimized Signal - Clean, stable output for accurate readings
• Safe Operation - Protected inputs prevent damage
• Wide Compatibility - Works with all SCT-013 models
• Precision Components - Ensures measurement accuracy
• Low Noise - Filtered output for stable readings