BD139 (8 pcs) Transistor

===============================================================================

The BD139 and BD140 are NPN and PNP power transistors, respectively, commonly used in switching and amplification applications, especially in higher power circuits. These transistors are widely used in audio amplification, motor control, and power regulation circuits, particularly when high current handling capabilities and robust performance are required.

• BD139: NPN power transistor
• BD140: PNP power transistor

These transistors are complementary pairs, designed to work together in push-pull configurations for efficient signal amplification and power control.

Key Features:

• Type:
  • BD139: NPN power transistor
  • BD140: PNP power transistor
• Collector-Emitter Voltage (Vce): 80V (maximum)
• Collector Current (Ic): 1.5A (maximum)
• Power Dissipation: 12W (maximum)
• Current Gain (hFE): Typically 40 to 320, depending on the specific model.

How They Work:

1. Complementary Push-Pull Amplification:

   • The BD139 (NPN) and BD140 (PNP) are often used together in push-pull amplifier circuits, particularly in audio amplifiers. In such circuits, the NPN transistor (BD139) amplifies the positive part of the signal, while the PNP transistor (BD140) amplifies the negative part of the signal.
   • By combining the two transistors in this configuration, the circuit is able to efficiently amplify both halves of the input signal, making the output more powerful and reducing distortion.
   • This configuration is particularly useful in class AB amplifiers, where both transistors conduct simultaneously to increase efficiency while minimizing distortion and power losses.

2. Switching Applications:

   • Both transistors can be used individually as switches. When a small current is applied to the base, it allows a larger current to flow between the collector and emitter.
   • The BD139 (NPN) transistor is typically used to switch the load from the negative side of the circuit, while the BD140 (PNP) transistor switches the load from the positive side of the circuit.
   • These transistors can be used in motor drivers, relay drivers, and other applications requiring the switching of higher power loads, such as in industrial control systems.

3. Power Amplification:

   • The BD139 and BD140 are often used in power amplifiers to drive loudspeakers or other high-power components. They can handle a significant amount of power and are used in audio circuits for efficient sound amplification.
   • These transistors provide the required current to drive loudspeakers, making them ideal for audio systems, public address systems, and home theater amplifiers.

Pin Configuration:

1. BD139 (NPN):

   • Collector (C): The output terminal, typically connected to the load (e.g., speaker, motor, etc.).
   • Base (B): The input terminal where a small current is applied to control the transistor's operation.
   • Emitter (E): The reference terminal, usually connected to ground or a lower voltage source.

2. BD140 (PNP):

   • Collector (C): The output terminal, typically connected to the load.
   • Base (B): The input terminal, where a small current controls the operation of the transistor.
   • Emitter (E): The reference terminal, typically connected to a positive voltage source.

Example Circuits:

1. Push-Pull Amplifier Circuit:

   • In a push-pull amplifier, the BD139 (NPN) and BD140 (PNP) transistors work together to amplify both halves of the AC signal. The NPN transistor handles the positive portion of the waveform, while the PNP transistor handles the negative portion.
   • The signal is applied to the bases of the transistors, and the transistors alternate between conducting and non-conducting states to provide the necessary current to the load (such as a speaker).

2. Motor Driver Circuit:

   • The BD139 and BD140 can be used in a H-bridge configuration to control the direction and speed of a motor.
   • The NPN transistor (BD139) can control current flow in one direction, and the PNP transistor (BD140) can control current flow in the opposite direction, making it possible to reverse the motor's direction when needed.

3. Relay Driver Circuit:

   • These transistors can also be used to drive relays in circuits where the load requires more current than a standard switch can handle. The BD139 can switch the low side, while the BD140 can switch the high side of the relay coil.

Key Notes:

• BD139 and BD140 are ideal for use in high-power amplification circuits, such as audio amplifiers, where large currents are required.
• These transistors are frequently used together in push-pull configurations to ensure efficient amplification and reduced distortion in audio circuits.
• Both transistors are suitable for driving motors, relays, and other power components that require switching capabilities with high current and voltage.
• Ensure the use of appropriate base current limiting resistors to protect the transistors from excessive current and possible damage.