Transistor NPN bc 547

🛠️ NPN Transistor – BC547 (TO‑92 Package)

Overview

The BC547 is a general-purpose silicon NPN transistor, commonly used for switching, signal amplification, and sensor interfacing in low-power electronics. It’s a favorite for hobbyists and professionals due to its versatility and reliability.

Key Features

• Collector current: up to 100 mA

• Collector–Emitter voltage (Vₙₑₒ): 45 V

• Collector–Base voltage (Vₙₑₒ): 50 V

• Power dissipation: 625 mW

• Gain (h_FE): 110–800 (varies by variant A/B/C)

• Transition frequency (fₜ): ~300 MHz

• Package: TO‑92 (flat face, leads downward)

Pinout

With the flat front facing you and leads pointing down:

1. Collector (left)
2. Base (middle)
3. Emitter (right)

Typical Arduino Switching Circuit

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Arduino GPIO → 1 kΩ resistor → Base
Emitter → Arduino GND
Collector → Load → +V supply

Applications

• Driving LEDs, small relays, or motors

• Signal amplification in audio circuits

• Pulse width modulation (PWM) for fan or LED control

• Sensor interfacing and logic-level switching

• Oscillators and timing circuits

✅ Resources

1. 📄 Datasheet: ON Semiconductor BC546/547/548 series — provides full electrical ratings, pinouts, and characteristics media.digikey.com+3edn.com+3cdn.sparkfun.com+3

2. 🎥 YouTube Tutorial: "How to use the 2N3904/BC547 NPN transistor as a switch" — includes wiring examples and Arduino interface instructables.com+15youtube.com+15circuits-diy.com+15