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BC547 Transistor Introduction

BC547 is a general BJT NPN transistor, which is mainly used for electronic lovers and educational electronic projects.

What is BC547 Transistor

BC547 is an NPN transistor, so when the base pin is grounded, the collector and emitter will remain disconnected (reverse bias); when the signal is supplied to the base pin, the collector and emitter will be closed (forward bias). The gain value of bc547 is 110 to 800, which determines the amplification capacity of transistor. The maximum current flowing through the collector pin is 100mA, so we can’t connect the load consuming more than 100mA with this transistor. In order to bias the transistor, we have to supply current to the base pin, which should be limited to 5mA.

When the transistor is fully biased, it allows a maximum current of 100 mA to flow through the collector and emitter. This stage is called saturation region, and the typical voltage allowed for cross collector emitter (V ­ CE) or base emitter (v be) is 200 and 900 MV respectively. When the base current is removed, the transistor is completely cut off. This stage is called cut-off region, and the base emitter voltage may be about 660 MV.

BC547 datasheet

BC547 Pinout &Configuration

BC547 has three terminals, as shown in the table.

Pin NumberPin NameDescription
1CollectorCurrent flows in through collector
2BaseControls the biasing of transistor
3EmitterCurrent Drains out through emitter
BC547 Pinout &Configuration

BC547 Features

  1. Package Type: TO-92
  2. Transistor Type: NPN
  3. Max Collector Current(IC): 100mA
  4. Max Collector-Emitter Voltage (VCE): 45V
  5. Max Collector-Base Voltage (VCB): 50V
  6. Max Emitter-Base Voltage (VEBO): 6V
  7. Max Collector Dissipation (Pc): 500 miliWatt
  8. Max Transition Frequency (fT): 300 MHz
  9. Minimum & Maximum DC Current Gain (hFE): 110 – 800
  10. Max Storage & Operating temperature Should Be: -65 to +150 Centigrade

BC547 equivalent transistor

  • The BC547 equivalent transistors are: 2N2222, 2N3904, 2N4401, BC337
  • The BC547 pnp complementary is: BC557

How does a BC547 transistor work?

As mentioned above, BC547 is a widely used transistor, which can be used in any general application, and can also be used as a substitute and substitute for many transistors, so it can be used in various electronic circuits, such as switching very low load input voltage and current under a very small load, and amplifying audio and other signals. The maximum transition frequency of transistor is 300MHz, so it can work well in RF circuit at 300MHz

BC547 Transistor as switch

When the crystal tube is used as a switch, it operates in the saturation and cut-off regions as described above. As mentioned earlier, the transistor will be used as an off switch during forward bias and as a close switch during reverse bias, which can be achieved by providing the required current to the base pin. As mentioned before, the bias current shall be 5 Ma maximum. Any current greater than 5mA will kill the transistor. Therefore, a resistor is always connected in series on the base pin. The resistance value (RB) of the resistor can be calculated using the following formula.

B  = V BE / I B

Where the value be of V should be 5V for bc547 and base current (I B depends on collector current (I C ^). My value B should not exceed ma.

BC547 Transistor as Amplifier

A Transistors acts as an Amplifier when operating in Active Region. It can amplify power, voltage and current at different configurations.

Some of the configurations used in amplifier circuits are

  1. Common emitter amplifier
  2. Common collector amplifier
  3. Common base amplifier

Of the above types common emitter type is the popular and mostly used configuration. When uses as an Amplifier the DC current gain of the Transistor can be calculated by using the below formulae

DC Current Gain = Collector Current (IC) / Base Current (IB)

BC547 Applications

  • Driver Modules like Relay Driver, LED driver etc..
  • Amplifier modules like Audio amplifiers, signal Amplifier etc..
  • Darlington pair

That’s all for today. Hope you enjoyed this article. However, if you have doubts or have any questions about this, you can contact me in the comments section below. I’ll be happy to help you as best I can. Let us know your feedback and suggestions at any time, they allow us to provide you with high-quality work that responds to your needs and expectations, and helps you continue to give back to our products. Thank you for reading this article.


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  1. […] BC549 equivalent transistors are: BC547, BC548, […]

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