The BC547 NPN Epitaxial Silicon Transistor is arguably the most essential component in any electronics toolkit. At Electrapac, we consider this the "Swiss Army Knife" of transistors, perfect for students, hobbyists, and professional engineers across Bangladesh who need a reliable, low-power general-purpose amplifier or switch.

Product Overview

The BC547 is a Negative-Positive-Negative (NPN) bipolar junction transistor (BJT) housed in the standard TO-92 plastic package. It is designed specifically for low-current, low-voltage applications. Whether you need to drive an LED, trigger a relay from an Arduino, or amplify a weak audio signal, the BC547 provides stable and predictable performance.

Key Features for Electrapac Customers

• High Gain (h_FE): With a gain of up to 800, the BC547 can easily turn a tiny microampere signal from a sensor into enough current to drive a load.

• Low Noise: Excellent for pre-amplifier stages in audio circuits, ensuring clear signal reproduction without adding unwanted hiss.

• Fast Switching: Capable of high-speed switching, making it suitable for PWM (Pulse Width Modulation) control and digital logic circuits.

• Compact TO-92 Design: The small footprint makes it easy to fit into crowded breadboards or compact PCB layouts for DIY robotics.

• Cost-Effective Reliability: Known for its ruggedness and extremely low cost, it is the ideal "learning transistor" for electronics students in Bangladesh.

Pinout & Connection Guide

When looking at the flat side of the BC547 with the pins pointing downwards, the pinout is as follows:

1. Pin 1 (Left): Collector (Connects to the Load).

2. Pin 2 (Middle): Base (The control trigger; usually connected to a resistor).

3. Pin 3 (Right): Emitter (Usually connected to Ground in a common-emitter circuit).

Pro-Tip: Always use a base resistor (typically 1kΩ to 10k Ω) when connecting the BC547 to an Arduino or ESP32 pin. This prevents the transistor from drawing too much current and damaging your microcontroller.

Primary Applications

• Switching: Using a small microcontroller signal to turn on LEDs, Buzzers, or small DC Motors.

• Signal Amplification: Boosting the output of a microphone or a light sensor (LDR).

• Logic Gates: Building basic AND/OR/NOT logic circuits from scratch.

• Relay Driving: Acting as the bridge between a low-power sensor and a high-power relay.

• Pulse Width Modulation (PWM): Controlling the brightness of an LED or the speed of a tiny fan.

Why Shop at Electrapac?

We source our BC547 Transistors from reputable manufacturers to ensure they meet the specific gain and voltage ratings required for precision work. Visit us at for the essential components that bring your circuit designs to life.