NPN Transistor BC337 (BJT)
🔋 BC337 – NPN Bipolar Junction Transistor (BJT)
The BC337 is a general-purpose NPN transistor used in a wide range of switching and amplification applications. With a collector current of up to 800mA, it is ideal for driving relays, LEDs, motors, and small audio or signal amplification in Arduino, ESP32, or other microcontroller projects.
⚙️ Technical Specifications
| Parameter | Specification |
|---|---|
| Transistor Type | NPN BJT |
| Part Number | BC337 |
| Max Collector-Emitter Voltage | 45V |
| Max Collector Current | 800 mA |
| Max Power Dissipation | 625 mW |
| DC Current Gain (hFE) | 100–630 (depending on model) |
| Transition Frequency | ~100 MHz |
| Package | TO-92 (through-hole, 3 pins) |
| Complementary PNP | BC327 |
📎 Pin Configuration (TO-92)
FRONT VIEW _______ | | | | |_______| | | | C B E
C – Collector
B – Base
E – Emitter
✅ Features
⚙️ General-purpose NPN transistor
🔌 Suitable for switching applications (up to 800mA)
🔊 Can be used in audio amplification circuits
🧩 Compatible with Arduino, Raspberry Pi, and DIY electronics
🛠️ Easy to prototype on breadboards or PCBs
🧪 Example Application: LED Switching
Wiring:
Connect emitter to GND
Connect collector to LED (and then to resistor + Vcc)
Connect base to Arduino pin through a 1kΩ resistor
Arduino Code Example:
CopyEditint ledPin = 3; // Connected to base via 1k resistor void setup() { pinMode(ledPin, OUTPUT); } void loop() { digitalWrite(ledPin, HIGH); // Turns LED ON delay(1000); digitalWrite(ledPin, LOW); // Turns LED OFF delay(1000); }