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Relay & 220V Control | NexaLearn IoT Lab | NexaLearn

High-Voltage Control & Safety30 دقيقة

Relay & 220V Control

How to switch a home light bulb through Arduino safely.

Lesson Content

A relay is a mechanically operated switch activated electromagnetically. A 5V current from Arduino passes through to attract a metal piece inside the relay with a 'click', which closes a 220V high-current circuit on the other side. Arduino is completely isolated. STRICT WARNING: Household electricity is lethal! Never work on this project while the power is connected. Use tape to insulate exposed wires and ensure you cut only the 'live' wire to pass through the relay.

Components Needed

Arduino UnoRelay Module 1 Channelمصباح أو مروحة صغيرة

Wiring Notes

Relay power: VCC, GND, and IN to Arduino. High-voltage side: the cut wire connects to COM (Common) and NO (Normally Open) terminals.

Code Example

const int relayPin = 7;
void setup() {
  pinMode(relayPin, OUTPUT);
}
void loop() {
  digitalWrite(relayPin, HIGH); // بعض موديلات الريلاي تعمل بـ LOW لتشغيلها
  delay(5000);
  digitalWrite(relayPin, LOW);
  delay(5000);
}

Common Mistakes

Connecting both wires (live and neutral) inside the relay — this will cause a massive short circuit and explosion when the relay triggers. The relay cuts only ONE wire, just like a regular wall light switch.

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Introduction to ESP32 and Wi-Fi