110/220VAC optically isolated zero-crossing detector module for DIN rail bracket mounting with 3.3V or 5V output - ideal for Arduino, ESP32/ESP8266

This module detects the zero-crossing point of the AC power supply and outputs a 1ms 3.3V or 5V square wave signal pulse at each zero-crossing. For a 50Hz power supply, this pulse is sent 100 times per second. This is ideal for microcontroller projects that require precise synchronization with AC power, such as phase angle control for controlling triacs to perform dimming or heater control. The AC and DC sides of the circuit are optically isolated, providing important safety and protection for the microcontroller. AC power is connected to the upper terminal block, and the lower terminal block is connected to the microcontroller, sharing its DC 3.3V or 5V and ground, and sending the output signal to the designated GPIO pin to trigger the interrupt code. The board features micro-LED indicators and is designed to fit into the Camdenboss DIN rail enclosure for easy installation. This module adds to a growing list of DIN rail-based accessories for microcontroller projects, enabling a "plug and play" approach to speeding up project builds. Caution - This circuit uses dangerous AC mains voltages and may cause electric shock or fire. Must be independently reviewed and certified by qualified professionals prior to use. The designer assumes no responsibility for the assembly or use of this module in any way.