MOSFET Transistor

Pinout — MOSFET Transistor

Wiring notes

3-pin TO-220 component. Use componentId transistor-mosfet and put the part number + channel type + (optional) 'logic-level' in the label, e.g. 'IRLZ44N N-ch logic-level', 'IRFZ44N N-ch', 'IRF9540 P-ch'. Pins: G (Gate), D (Drain), S (Source). N-channel low-side: Source to GND, Drain to load (load other side to Vcc), Gate to Arduino pin via 100Ω with 10kΩ pull-down to GND. P-channel high-side: Source to Vcc, Drain to load (load other side to GND), Gate via 100Ω with 10kΩ pull-up to Vcc (active-low). For inductive loads (motors, relays, solenoids) ALWAYS add a flyback diode across the load. With a 5V/3.3V Arduino, prefer logic-level parts (IRLZ44N, IRL540N) — standard parts won't fully turn on and will overheat.

Example wiring diagram — MOSFET Transistor

Example Arduino code — MOSFET Transistor

This example was written and compile-checked for the arduino-uno. Codey Online adapts it to any other supported board for you.

const int mosfetGatePin = 4;

void setup() {
  pinMode(mosfetGatePin, OUTPUT);
  digitalWrite(mosfetGatePin, LOW);  // MOSFET off at startup

  Serial.begin(9600);
  Serial.println("MOSFET transistor demo: switching an LED with an N-channel logic-level MOSFET.");
}

void loop() {
  Serial.println("MOSFET ON");
  digitalWrite(mosfetGatePin, HIGH);
  delay(1000);

  Serial.println("MOSFET OFF");
  digitalWrite(mosfetGatePin, LOW);
  delay(1000);
}

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