IoT High-Power Switch Controller

Wi-Fi controlled high-power switching board using NodeMCU (ESP8266) with relay, optocoupler isolation, and AC-DC converter modules for remote industrial load control

Project Overview

Designed and built an IoT-enabled high-power switching controller capable of remotely switching industrial loads via Wi-Fi. The board combines a NodeMCU (ESP8266) for wireless control with relay and optocoupler-isolated switching stages, multiple AC-DC converter modules for galvanic isolation, and high-current screw terminal outputs. The system was tested live with an industrial-grade contactor.

Board close-up showing NodeMCU, relay, optocoupler switches, and AC-DC converter modules (left). Live testing setup with the board driving an industrial contactor under real load conditions (right).

Key Features

  • Wi-Fi Remote Control — NodeMCU (ESP8266) enables wireless switching from any network-connected device
  • Relay Output — SONCE SRD-05VDC relay for one isolated high-power channel
  • Optocoupler Isolation — transistor/optocoupler switching stages for safe control of high-voltage loads
  • AC-DC Converter Modules — per-channel isolated power supplies for robust galvanic separation
  • Multi-Channel Outputs — multiple high-current screw terminal pairs for independent load control
  • Industrial Load Tested — validated live against an industrial contactor under real operating conditions

Hardware Architecture

Block Implementation
Wi-Fi Controller NodeMCU (ESP8266) — HTTP / MQTT remote switching
Relay SONCE SRD-05VDC-SL-C — isolated mechanical switch
Isolation Optocoupler / transistor array — high-voltage control isolation
Power AC-DC converter modules — per-channel galvanic isolation
Outputs High-current screw terminals — direct industrial load connection

Technologies & Tools

  • NodeMCU / Arduino IDE — ESP8266 firmware and Wi-Fi control logic
  • PCB design — custom board layout
  • Relay and optocoupler circuit design
  • AC-DC power supply integration
  • Industrial load testing and validation

Key Achievements

✅ Built a Wi-Fi controlled multi-channel high-power switching system
✅ Implemented galvanic isolation via optocouplers and AC-DC converters
✅ Validated live with an industrial contactor under real load
✅ Compact single-board design integrating control, isolation, and power