BC547 Transistor: Pin out, Features & Applications

Bc547 Transistor

BC547 Transistor is a general-purpose transistor mostly used in educational and electronics projects and It is also used in commercial circuits as well as in hobbies projects. It is a tiny three-terminal device capable to convert small signal inputs into large amplified outputs. It is a BJT (Bipolar Junction Transistor) NPN transistor that comes in TO-92 packaging and it can handle 100mA output current. The transistor, BC 547 is shown below.

BC547 Transistor Pinout:

Bc547 transistor has three terminals Collector, Base, and Emitter. Pin detail is clearly shown in the figure given below.

Bc547 Transistor

BC547 Transistor Features:

  • Package-Type: TO-92
  • Bi-Polar NPN Transistor
  • DC Current Gain (HFC) is 800 maximum
  • Max Collector current (IC) is 100mA
  • Emitter Base Voltage (VEBO) is 6V
  • Max Collector-Base Voltage (VCB): 50V
  • Base Current(IB) is 5mA maximum

PNP Complementary:

The complement of BC547 is PNP BC557, BC558.

Replacement and Equivalent:

You can replace bc 547 with bc548, Bc5492N2222, 2N3904, 2N4401, BC337. The Pin configuration of some transistors is different from BC547 so check pin configuration before replacing in a circuit.

SMD Equivalent

The SMD of the BC547 is available as the BC847, BC847W, BC850, and BC850W.

Applications of Transistor BC547

A lot of applications associated with BC547, a few of the main applications are given below.

    • Sensor Circuits
    • Audio Preamp circuits
    • Audio Amplifier Stages
    • Switching Loads under 100mA
    • Transistor Darlington Pairs
    • Radio Frequency Circuits

How to Protect Transistor:

For the long life of bc547 do not increase load more than 100mA on it, and do not exceed the voltage across this transistor to 45V DC. Always use a relevant base resistor to provide the required current for saturation because more current on base can damage the transistor. The temperature does not above +150 centigrade and below -65 centigrade. Always confirm the collector-emitter and base pins before placing them in the circuit. If accidentally placed wrong in a circuit then check its performance again because wrong input can decrease its efficiency.

BC547 as Switch

In a switch, it is operated in the Saturation and Cut-Off Region. A transistor acts as an Open switch during forwarding and as a Closed switch during Reverse Bias, this biasing can only be achieved by supplying the required amount of current to the base pin of the transistor. As mentioned above the biasing current maximum of 5mA. More current than 5mA will kill the Transistor; so, a resistor is always be added in series with base pin. We can calculate the value of the resistor (RB) using the below formulae.

RB  = VBE / IB

BC547 as Amplifier

A transistor acts as an Amplifier while operating in Active Region. BC547 can amplify power, voltage, and current at different configurations.

Some configurations used in amplifier circuits are

    • Common collector amplifier projects
    • amplifier
    • Common base amplifier

The formula used for the amplifier: DC Current Gain = Collector Current (IC) / Base Current (IB)

Circuits Using BC547 Transistors

First of all, We want to show you how can you use bc547 transistors in projects. We are going to show you a simple touch on the circuit by using 547. This will clear your concept of the working of transistor bc547,bc548bc549, and other transistors the same as this.

Touch on circuit using bc547

This simple circuit clear shows that when you touch the points shown in the circuit. A small amount of + current flows through the figure from + to base and this small current turns on the transistor.

Some other projects using BC547 Transistors