The BC142 is a silicon NPN power transistor and it is used in medium to power switching and amplifier circuits. This is an NPN silicon planar epitaxial transistor. The transistor is comes in TO-39 metal packaging. In this article I’m sharing the pinout configuration, equivalent transistor for replacement and its specifications. This will help you to know its information before placing the components on PCB.
BC142 Transistor Pinout Configuration
When you holding the transistor in down and pins are facing up, the small metal in the transistor body is keep in left and count the pin in clock wise direction. The Pin 1 is emitter Pin 2 is collector and Pin 3 is Base. which rea also mentioned in the given table and Figure 1.
| Pin Number | Name |
|---|---|
| 1 | Emitter |
| 2 | Collector |
| 3 | Base |
BC142 Transistor Pinout
Characteristic’s of the Transistor
| Parameter | Value | Unit | Description |
|---|---|---|---|
| Transistor Type | NPN | – | Silicon-based bipolar junction transistor |
| Collector-Emitter Voltage (VCEO) | 60 | V | Maximum voltage between collector and emitter |
| Collector-Base Voltage (VCBO) | 80 | V | Maximum voltage between collector and base |
| Emitter-Base Voltage (VEBO) | 5 | V | Maximum voltage between emitter and base |
| Collector Current (IC) | 1 | A | Maximum continuous collector current |
| Total Power Dissipation | 0.8 | W | Max power the transistor can handle |
| DC Current Gain (hFE) | 40 – 250 | – | Current gain (amplification factor) |
| Operating Temperature Range | -65 to +150 | °C | Safe operating temperature range |
| Package Type | TO-39 | – | Metal can package for better heat dissipation |
Equivalent Transistors
- BD135 – NPN power transistor with similar voltage and current ratings.
- BD139 – Popular NPN transistor often used in amplifier and switching circuits.
- TIP31- Higher power NPN transistor; suitable when more current capacity is needed.
- 2N1711 – Metal case transistor similar in function and packaging (TO-39).
- 2N3053 – General-purpose NPN transistor with TO-39 package, often interchangeable in medium-power circuits.
Applications
- Audio Amplifiers.
- Switching Circuits.
- Power Supply Circuits
- Signal Amplification.
