How to Use BC547C: Examples, Pinouts, and Specs

The BC547C is a general-purpose NPN bipolar junction transistor (BJT) manufactured by Diotec. It is widely used in amplification and switching applications due to its reliable performance and compact size. With a maximum collector current of 100 mA and a maximum collector-emitter voltage of 45 V, the BC547C is ideal for low-power electronic circuits. Its high current gain (hFE) range of 420 to 800 makes it particularly suitable for signal amplification in audio, RF, and other low-power applications.

• Signal amplification in audio and RF circuits
• Low-power switching applications
• Oscillator and timer circuits
• General-purpose amplification in hobbyist and educational projects

The BC547C is housed in a TO-92 package with three pins. The pinout is as follows:

The pinout diagram for the TO-92 package is shown below (viewed from the flat side of the package):

   _______
  |       |
  |       |
  |_______|
   | | |
   1 2 3
   C B E

The BC547C can be used in two primary configurations: as an amplifier or as a switch.

To use the BC547C as an amplifier:

• Connect the emitter to ground through a resistor (RE).
• Connect the collector to the positive supply voltage (Vcc) through a load resistor (RC).
• Apply the input signal to the base through a coupling capacitor and a base resistor (RB).
• The amplified output signal will appear across the load resistor (RC).

To use the BC547C as a switch:

• Connect the emitter to ground.
• Connect the load (e.g., an LED with a current-limiting resistor) between the collector and Vcc.
• Use a base resistor (RB) to limit the base current and connect the base to the control signal.
• When the base voltage exceeds 0.7 V, the transistor will turn on, allowing current to flow through the load.

• Always use a base resistor to limit the base current and prevent damage to the transistor.
• Ensure that the collector current (Ic) does not exceed 100 mA.
• Avoid exceeding the maximum voltage ratings (Vce, Vcb, and Veb) to prevent breakdown.
• Use proper heat dissipation techniques if the transistor operates near its maximum power dissipation (500 mW).

The BC547C can be used to control an LED with an Arduino UNO. Below is an example circuit and code:

• Connect the emitter (E) to ground.
• Connect the collector (C) to one terminal of the LED through a 330 Ω resistor. Connect the other terminal of the LED to Vcc (5 V).
• Connect the base (B) to an Arduino digital pin (e.g., pin 9) through a 1 kΩ resistor.

// Define the pin connected to the BC547C base
const int transistorBasePin = 9;

void setup() {
  // Set the transistor base pin as an output
  pinMode(transistorBasePin, OUTPUT);
}

void loop() {
  // Turn the LED on by applying a HIGH signal to the base
  digitalWrite(transistorBasePin, HIGH);
  delay(1000); // Keep the LED on for 1 second

  // Turn the LED off by applying a LOW signal to the base
  digitalWrite(transistorBasePin, LOW);
  delay(1000); // Keep the LED off for 1 second
}

• Use a pull-down resistor on the base pin to ensure the transistor remains off when no signal is applied.
• For higher currents, consider using a transistor with a higher current rating.

Q1: Can the BC547C handle currents above 100 mA?
A1: No, the maximum collector current (Ic) is 100 mA. Exceeding this limit may damage the transistor.

Q2: What is the difference between BC547A, BC547B, and BC547C?
A2: The main difference is the DC current gain (hFE) range:

• BC547A: 110 to 220
• BC547B: 200 to 450
• BC547C: 420 to 800

Q3: Can I use the BC547C for high-frequency applications?
A3: Yes, the BC547C has a transition frequency (fT) of 300 MHz, making it suitable for high-frequency applications.

Q4: How do I test if my BC547C is working?
A4: Use a multimeter in diode mode to check the base-emitter and base-collector junctions. A forward voltage drop of ~0.6-0.7 V indicates a functional transistor.

By following this documentation, you can effectively use the BC547C in your electronic projects.