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NPN Transistor (2N2222)

A widely used NPN bipolar junction transistor used for amplifying or switching electronic signals and electrical power.

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TO-92 Package

The 2N2222 is a common NPN bipolar junction transistor (BJT) used for general purpose low-power amplifying or switching applications. It acts as an electrically controlled switch: a small current at the Base controls a larger current flowing from Collector to Emitter.

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Pin Reference

Pin	Type	Description
E (Emitter)	passive	Current flows out of the Emitter to Ground.
B (Base)	input	Control pin. A small current here turns the transistor ON.
C (Collector)	passive	Current enters the Collector from the load/VCC.

Configurable Attributes

This component has no configurable attributes.

Wiring Diagram

Example of connecting the NPN Transistor as a switch. A digital pin drives the Base (through a current-limiting resistor, not shown in basic diagram but required in practice) to switch a load on the Collector.

Example Arduino Code

The transistor acts as a switch. Driving the base pin HIGH allows current to flow through the Collector to Emitter.

const int basePin = 3; // Connect to the Base (B) of the NPN transistor

void setup() {
  pinMode(basePin, OUTPUT);
}

void loop() {
  // Turn the transistor ON (allowing current from C to E)
  digitalWrite(basePin, HIGH);
  delay(1000);
  
  // Turn the transistor OFF (blocking current)
  digitalWrite(basePin, LOW);
  delay(1000);
}