PC817 Optocoupler – 4-Pin DIP Isolation IC

🔌 PC817 Optocoupler – 4-Pin DIP Isolation IC

The PC817 is a widely used optocoupler (optical isolator) that combines a light-emitting diode (LED) and a phototransistor in a single 4-pin DIP package. It is ideal for isolating high-voltage circuits from low-voltage control systems such as Arduino, Raspberry Pi, PLC, or MCUs, protecting them from voltage spikes or noise.

⚙️ Technical Specifications

✅ Features

• 🧲 Electrical isolation between input and output

• ⚡ Protects microcontrollers from high-voltage circuits

• 📦 Small DIP-4 package, easy to solder or breadboard

• 🔄 Fast switching for digital signal transmission

• 🔐 Helps eliminate ground loops and electrical noise

• 🛠️ Common in SMPS, microcontroller interfacing, sensor isolation, and relay control

🛠️ Typical Applications

• Relay driver isolation

• Microcontroller digital input protection

• PLC/industrial signal interfacing

• Power supply feedback

• Signal level shifting

📘 Arduino Example (Digital Isolation)

// PC817 used to isolate an input button
const int inputPin = 2;

void setup() {
  pinMode(inputPin, INPUT);
  Serial.begin(9600);
}

void loop() {
  if (digitalRead(inputPin) == HIGH) {
    Serial.println("Input Detected via Optocoupler");
  }
}

Input side (anode & cathode) connected with resistor (e.g., 220Ω) to a 5V trigger source.

🎥 Tutorial