Isolated AC mains Voltage Detection Module

Description

Isolated AC mains Voltage Detection 5V and 3.3V output level compatible

Overview

The AC 220V Mains Voltage Sensor Module is a safe and isolated detection board designed to sense the presence of AC mains voltage (110V–250V).
It provides a logic-level signal output suitable for microcontrollers such as Arduino, ESP32, STM32, or Raspberry Pi to detect whether mains power is present or absent.

The module features optical isolation using the PC817 optocoupler and includes an onboard LED indicator for visual power status feedback.

Features

• Safe isolation from high-voltage AC mains

• Onboard LED indicates when mains power is detected

• Optocoupler isolation (PC817) for MCU protection

• Wide input range: 110–250V AC compatible

• Logic-level output (3.3V or 5V) for direct connection to microcontrollers

• Compact design with screw terminals for easy wiring

• Galvanic isolation ensures no direct connection between high-voltage and low-voltage circuits

• Designed for DIY, automation, and power monitoring projects

Technical Specifications

Pin Description (Output Header)

How It Works

1. The AC mains input (110–250V) is rectified and filtered to generate a low DC signal.

2. The PC817 optocoupler isolates and transfers the detection signal to the low-voltage side.

3. The logic output pin changes state based on AC presence:

   • HIGH (1) → Mains voltage detected

   • LOW (0) → Mains off

4. The onboard LED lights up when AC power is present.

Applications

• Power failure detection

• Home automation systems

• Generator or inverter monitoring

• Smart energy management systems

• Industrial control panels

• Safety monitoring in IoT projects

DIY / Maker Friendly

• Suitable for use with Arduino, ESP32, ESP8266, STM32, Raspberry Pi, and PIC controllers.

• Can be powered from 3.3V or 5V logic systems.