This post explains for the transistor.

The Part Number is 2SB857, B857.

The Package is TO-220AB Type

The function of this semiconductor is 50V, 4A, PNP Transistor.

Manufacturer: Renesas

Preview images :

Description

B857 is -50V, -4A, Silicon PNP Triple Diffused Transistor. 

Characteristics:

2. Current flow: When a small current is applied to the base terminal, it allows a much larger current to flow from the emitter to the collector. This is called amplification or gain, and it makes the PNP transistor useful as an electronic switch or amplifier.

3. Voltage levels: The voltage levels in a PNP transistor are opposite to those in an NPN transistor. In a NPN transistor, the base-emitter junction is forward-biased and the collector-base junction is reverse-biased.

Absolute maximum ratings ( Ta=25°C )

1. Collector to Base Voltage: Vcbo = – 70 V

2. Collector to Emitter Voltage: Vceo = – 50 V

3. Emitter to Base Voltage: Vebo = – 5 V

4. Collector Current: Ic = – 4 A

5. Collector Dissipation : Pc = 40 W

6. Junction Temperature: Tj = 150°C

7. Storage Temperature: Tsg = -45 ~ +150°C

 

Application:

1. Low frequency power amplifier complementary pair with 2SD1133 and 2SD1134

 

B857 PDF Datasheet

This post explains for the transistor.

The Part Number is A1972, 2SA1972.

The package is TO-92 Type

The function of this semiconductor is 400V, PNP Transistor.

Manufacturer: Toshiba Semiconductor

Preview images :

Description

A1972 is 400V, 0.5A, Silicon PNP Triple Diffused Type Transistor.

Characteristics:

1. Polarity: In a PNP transistor, the majority charge carriers are holes, which flow from the emitter to the collector. The emitter is negative relative to the base, and the collector is positive relative to the base.

2. Current flow: When a small current is applied to the base terminal, it allows a much larger current to flow from the emitter to the collector. This is called amplification or gain, and it makes the PNP transistor useful as an electronic switch or amplifier.

3. Voltage levels: The voltage levels in a PNP transistor are opposite to those in an NPN transistor. In a NPN transistor, the base-emitter junction is forward-biased and the collector-base junction is reverse-biased.

4. Biasing: PNP transistors are biased in the opposite direction to NPN transistors. To turn on a PNP transistor, the base must be more negative than the emitter, and to turn it off, the base must be more positive than the emitter.

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Absolute maximum ratings ( Ta=25°C )

1. Collector to Base Voltage: Vcbo = – 400 V

2. Collector to Emitter Voltage: Vceo = – 400 V

3. Emitter to Base Voltage: Vebo = – 7 V

4. Collector Current: Ic = – 0.5 A

5. Collector Dissipation : Pc = 900 mW

6. Junction Temperature: Tj = 150°C

7. Storage Temperature: Tsg = -55 ~ +150°C

 

A1972 PDF Datasheet