4-Channel Relay Module 5V/12V/24V — Optocoupler Isolation, High/Low Trigger, Arduino & Raspberry Pi

4-Channel Relay Module — 5V/12V/24V, Optocoupler Isolation, High/Low Trigger

This 4-channel relay module with optocoupler isolation allows an Arduino, ESP32, or Raspberry Pi to independently switch four AC or DC loads using digital output pins. Each channel is independently controlled and optocoupler-isolated, protecting the microcontroller from high-voltage transients. The most popular relay module size for home automation, multi-zone irrigation, and multi-channel switching projects.

Electrical Specifications

• Channels: 4 independent relay channels
• Coil Voltage: 5V / 12V / 24V (select version)
• Maximum AC Load: 250V / 10A per channel
• Maximum DC Load: 30V / 10A per channel
• Trigger: High level or low level (selectable)
• Isolation: Optocoupler per channel
• Contacts: SPDT — NO and NC per channel
• LED Indicators: Status LED per channel
• Control Interface: 4 digital input pins (IN1–IN4)

Wiring

• VCC: 5V (or 12V/24V) | GND: Ground
• IN1–IN4: Connect to Arduino/ESP32 digital output pins
• COM/NO/NC: Load connection terminals per channel

Arduino Example

// Control relay channel 1 (active LOW trigger)
const int relay1 = 2;
void setup() { pinMode(relay1, OUTPUT); digitalWrite(relay1, HIGH); } // OFF
void loop() {
  digitalWrite(relay1, LOW);  // ON
  delay(1000);
  digitalWrite(relay1, HIGH); // OFF
  delay(1000);
}

Typical Applications

• Smart home lighting control (4 zones)
• Multi-zone irrigation system
• HVAC zone control
• Industrial multi-channel switching
• Raspberry Pi home automation server

4-channel optocoupler-isolated relay module — independent control of 4 AC/DC loads for Arduino, ESP32, and Raspberry Pi home automation projects.

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