bc547 and bc548 difference

In this post, we compare BC547 vs BC548 transistor types, both of them are known as the common type of transistor type used at electronic circuits, BC547 and BC548 are the NPN bipolar junction transistors, the applications of them are mostly found on hobbyist circuits and lower power electronic circuit.

We compare BC547 and BC548 transistors specifications and technical details may helpful for users and students to know about both the identical transistor types.

We include pinout details, characteristics of components, power specifications, and applications of this 2 transistor

Pinout details of BC547 vs BC548

Pinout of bc547

  1. Collector
  2. Base
  3. Emitter
Pinout of bc547
Pinout of bc547

Pinout of bc548

  1. Collector
  2. Base
  3. Emitter


Pinout of bc548
Pinout of bc548

The name of BC547 and BC548 indicate a specific technical variation at both the transistors, as follow, 

B&C stands that 

The name B letter indicates that silicon material is used to build the transistor and the C letter indicates that, it is a transistor that handles low power audio frequency.

BC547 and BC548 both are NPN transistors which are known as through-hole type and (TO-92 package) externally.  

Power Features of BC547

  • Collector current (Ic) = 100mA
  • Collector-emitter voltage (Vce) = 65v
  • Collector-base voltage (Vcb) = 80v
  • Emitter-base voltage (Vbe) = 8v
  • Maximum current gain = 800A
  • Power dissipation = 625mW
  • Transistor frequency = 300mHZ
  • Operating temperature = 150˚C

Power Features of BC548

  • Collector current (Ic) = 500mA
  • Collector-emitter voltage (Vce) = 30v
  • Collector-base voltage (Vcb) = 30v
  • Emitter-base voltage (Vbe) = 5v
  • Maximum current gain = 110-800mA
  • Power dissipation = 625mW
  • Transistor frequency = 150mHZ
  • Operating temperature = -55 to +/- 150˚C

The BC547 vs BC548 is used at current amplification circuits, the working process as like a small amount of current at the base terminal will be responsible for the control of the high current at the collector terminal of the transistor. 

The particular process that happened at BC547 vs BC548 will make sure that this device is called the current controlling device.

At BC547 current gain will be 800A fixed and at BC548 it will be varied from 110 to 800A, so the maximum current gain and power dissipation of both the device may pick BC547 and BC548 for amplification processes.

And collector current (Ic) at both BC547 vs BC548 is different, BC547 have 100Maand BC548 have 500Ma, this indicates that emitter current is high at BC548, so BC548 can handle high currents than BC547. 

Working of BC547 and BC548 

When an input voltage at the base terminal of the transistor, some amount of current flow happened at the base-emitter terminal and current controlling may be enabled at the collector.

The voltage at the base emitter (Vbe) is negative at the emitter and positive at the base terminal.

The working principle is the same at BC547 and BC548, this is due to both transistors have the same specifications, which is BJT NPN transistor having almost the same voltage and current handling ability.

Special features of bc547

  • The BC547 transistor can have high voltages on the collector terminal than BC548, but this particular specification will not stop replacing the BC548 with BC547.
  • The current gain of the BC548 is wider than BC547
  • The circuit designed for BC548 will also replace with BC547, with the same working specifications.
  • The BC547 has a high breakdown voltage.
  • The BC548 has a low noise operation.

Merits of BC547 and BC548

  • High availability 
  • Lower cost
  • Works in lower voltages
  • Lower output impedance 
  • Speedy action 
  • Long life span 

Demerits of BC547 vs BC548

  • Highly heat sensitive 
  • Lower power application 
  • Thermal runaway is a common problem
  • Cannot handle high frequency

Applications of BC547 and BC548 

  • Sensor circuits 
  • Amplifier circuits
  • Audio preamp circuits
  • Touch switch circuits
  • RF circuits 
  • PWM circuits
  • Quick switching devices
  • Relay driving 
  • Alarm devices
  • LED flash circuits
  • Heat sensor circuits 


In this post, we try to compare both NPN transistors BC547 and BC548, from our practical experience and research we conclude that both of the transistors are identical on the technical specifications.

We can easily replace BC547 with BC548 and vice versa, this is due to the voltage and current specifications of BC548 vs BC547 is almost the same, the overall transistor device is calculated with maximum current gain, this must be same which 800A at both transistors is same.

The run transistor for a long time in a circuit, it is very important that doesn’t increase the load more than 100Ma-500mA, this is the main limitation of transistors, and also the DC voltage should not exceed the limit 45v.

The application of BC547 vs BC548 is only limited to lower voltage electronic circuits.


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