BC548 is a commonly used NPN transistor same as bc547.  The collector and emitter will remain open when the base pin is held at the ground and will close when a signal is provided to the base pin. BC548 has a gain value of 110 to 800, this value determines the Amplification capacity of the transistor. The maximum 500mA current can flow through the collector pin, so we cannot connect loads more than 500mA with this transistor. The maximum base current capacity is 5mA.

BC548 Transistor Pinout Chart

Pin Number

Pin Name




Current flows in through the collector



Controls the biasing of transistor



Current Drains out through the emitter


BC548 Transistor Pinout Diagaram


BC548 Transistor pinout

BC548 transistor comes in four different module numbers BC548, BC548A, BC548B, and BC548C. The Difference among the four is only their DC current gain value. BC548 current gain value is from 110 to 800, BC548A is from 110 to 220, BC548B is from 200 to 450 and BC548C is from 420 to 800.

Technical specifications of Transistor:

  • Bi-Polar NPN Transistor
  • Maximum Collector Current: 500mA 
  • Max Collector-Emitter Voltage: 30V
  • Maximum Collector-Base Voltage: 30V
  • Max Emitter-Base Voltage: 5V
  • Transition Frequency: 150 MHz
  • Max Collector Dissipation: 625MW
  • Min & Max DC Current Gain: 110 – 800
  • Max Storage & Operating temperature Should Be: -55 to +150C
  • Package Type: TO-92

Replacement and Equivalent:

BC547, 2N2222, BC549, BC550,2N3904,3906 are the alternate of BC548 but pin configurations may differ so, must check the pin configuration before the use of any alternate of BC548.

PNP Complementary

PNP Complementary of BC548 are BC556, BC557, and BC558.


  • Driver Modules like Relay Driver, LED driver, and switching modules.
  • Amplifier modules like Audio amplifiers, signal Amplifiers, etc.
  • Darlington pair can be made with this also.
  • Sensor Circuits

Melody generator circuit using BC548 Transistor

How to Safely Long Run in a Circuit:

To increase the performance of this transistor you should, must follow the guidelines and specifications given above in technical specifications. Do not drive the device above 30V, and always use the pins with the correct direction because wrong input can damage the transistor. Do not use the device at an over temperature of more than 150c.

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