Article

A solid-state relay (SSR) and AC voltage controller has been developed using a BTA41-1200BW TRIAC rated for 40A and 1200V, alongside an MOC3041 opto-triac. This system features two modes of operation: phase-angle AC voltage control and optically isolated ON/OFF relay mode.

In voltage-control mode, it utilizes a DIAC-triggered RC phase-angle technique for smooth regulation of output voltage from near zero to full mains level. The design minimizes component count and includes a tested PCB prototype, making it suitable for industrial automation and IoT applications.

The circuit can handle continuous currents up to 40A and operates at up to 1200V. A potentiometer allows for output voltage adjustment, and the circuit has been tested with a household power line. It supports safe microcontroller-based control of high-power AC loads, providing faster and more efficient operation than conventional electromechanical relays.