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C945 Transistor Datasheet, Pinout, Equivalent and Uses

Update Time: Jun 19, 2023      Readership: 7113

C945 Transistor

The C945 transistor is a versatile electronic component widely utilized in various low-power amplification and switching applications. In this comprehensive article, we delve into the key specifications, pinout details, equivalent transistors, and diverse applications of the C945 transistor. Whether you're a beginner or an experienced electronics enthusiast, this guide will equip you with essential knowledge to leverage the capabilities of the C945 transistor effectively.

What is The C945 Transistor?

The C945 transistor is a commonly used low-power NPN (Negative-Positive-Negative) bipolar junction transistor (BJT). It is part of a series of general-purpose transistors and is widely available in the market. The C945 transistor is designed to amplify small electrical signals or act as a switch in electronic circuits.

It features three layers of semiconductor material: a thin layer of P-type material sandwiched between two thicker N-type layers. The transistor has three terminals: the emitter, the base, and the collector. By controlling the current flow between the base and the emitter terminals, the C945 transistor can regulate the current flowing through the collector terminal.

With a maximum current rating of 150mA and a voltage rating of 50V, the C945 transistor is suitable for low-power applications. It is commonly used in audio amplifiers, oscillators, voltage regulators, and various general-purpose electronic circuits.

C945 Transistor Pinout

The C945 transistor has three terminals, each serving a specific function. Here is the pinout configuration of the C945 transistor:

1. Emitter (E): The emitter terminal is typically denoted by an arrow symbol on the transistor package. It is connected to the N-doped layer of the transistor and is responsible for emitting electrons or carrying the output current.

2. Base (B): The base terminal is the control terminal of the transistor. It is used to regulate the current flowing through the transistor by controlling the input signal. The base terminal is usually the center pin of the transistor.

3. Collector (C): The collector terminal is connected to the P-doped layer of the transistor. It acts as the output terminal, allowing the flow of current from the emitter to the collector. The collector terminal is often connected to the positive supply voltage in most circuits.

To summarize, the pinout configuration of the C945 transistor is as follows:

C945 Transistor Pinout
Emitter (E) - Connected to the N-doped layer
Base (B) - Control terminal for regulating current
Collector (C) - Connected to the P-doped layer and acts as the output terminal

C945 Transistor Features

Here's a table summarizing the features of the C945 transistor:


Feature Description
Transistor Type
NPN (Negative-Positive-Negative) Bipolar Junction Transistor (BJT)
Maximum Current Rating 150mA
Voltage Rating 50V
Package Type TO-92 (Transistor Outline 92)
Power Dissipation 625mW (Max)
Collector-Base Voltage (Vcbo) 60V
Collector-Emitter Voltage (Vceo) 50V
Emitter-Base Voltage (Vbe) 5V
DC Current Gain (hfe) Typically ranging from 60 to 400
Transition Frequency (ft) 150MHz (Typical)
Base-Emitter Saturation Voltage Typically 0.6V
Base-Emitter On Voltage Typically 0.75V
Base-Emitter Cutoff Voltage (Vbe) Maximum 5V (Vce = 5V, Ic = 0.1mA)
Storage and Operating Temperature -55°C to +150°C
Application Areas
Audio amplifiers, voltage regulators, oscillators, general-purpose amplification, and switching circuits

C945 Transistor Package

The C945 transistor is commonly available in the TO-92 package. The TO-92 package is a widely used transistor package type that offers a compact and easy-to-handle design. It features three leads or pins, which correspond to the emitter, base, and collector terminals of the transistor.

The TO-92 package has a distinctive shape, resembling a small plastic capsule. It is often black or beige in color. The dimensions of the TO-92 package can vary slightly depending on the manufacturer, but its typical size is approximately 4.8mm x 4.8mm x 4.0mm.

The TO-92 package is popular due to its simplicity, low cost, and compatibility with through-hole mounting techniques. It allows for easy integration into electronic circuits and is suitable for applications where space is limited.

C945 Transistor Package

C945 Transistor Equivalent Parts

While it's always recommended to use the exact specified transistor for a given circuit, there are some equivalent transistors that can be used as substitutes for the C945 transistor. These equivalents have similar characteristics and can be interchanged in many applications. Here are a few commonly used equivalent parts for the C945 transistor:

1. 2N3904: The 2N3904 is an NPN transistor that is widely regarded as a suitable substitute for the C945. It has similar voltage and current ratings, making it a commonly used alternative.

2. BC547: The BC547 is another NPN transistor that can be used as a substitute for the C945. It has comparable characteristics and is readily available.

3. S8050: The S8050 is an NPN transistor that can also be used as a substitute for the C945. It has similar voltage and current ratings and is commonly used in low-power applications.

When using equivalent transistors, it's important to refer to their respective datasheets to ensure compatibility with the specific circuit requirements.

C945 Transistor Uses

The C945 transistor is a versatile component with various applications in low-power electronic circuits. One of its primary uses is in amplification, where it plays a vital role in audio amplifiers by boosting weak audio signals to a level suitable for driving speakers or headphones. Additionally, the C945 transistor is widely employed as a switch, allowing the control of current flow in electronic circuits. By receiving an input signal, it can turn on or off lights, activate relays, or drive motors. The transistor's ability to generate oscillations makes it valuable in oscillator circuits, serving as a key component in signal generators, tone generators, and timing circuits. Furthermore, the C945 transistor is utilized in voltage regulator circuits to stabilize and regulate output voltages, ensuring consistent power supply for other components. Its flexibility also extends to general-purpose circuits, where it finds applications in signal processing, logic gates, timers, and more. Overall, the C945 transistor's low-power capabilities and versatile nature make it an essential component in numerous electronic devices and systems.

C945 Transistor

C945 Transistor Datasheet

The C945 Transistor Data Sheet provides comprehensive specifications, pinout configurations, and application notes.

Click and review: C945 Transistor Datasheet

C945 Transistor Price

The price of the C945 transistor can vary depending on factors such as quantity, supplier, and location. Generally, the C945 transistor is an inexpensive component, with prices ranging from a few cents to a few dollars per unit, making it affordable for a wide range of electronic projects and applications. It is advisable to check with electronic component distributors or online retailers to obtain the most up-to-date and accurate pricing information.

C945 NPN Transistor

C945 VS BC547

The C945 transistor and the BC547 transistor are both NPN bipolar junction transistors (BJTs) commonly used in low-power applications. While they share similarities, there are some key differences between the two:

Electrical Characteristics: The C945 transistor typically has a higher maximum current rating (150mA) compared to the BC547 (100mA). However, the BC547 generally has a higher DC current gain (hfe) range, which can vary from 110 to 800, whereas the C945 typically ranges from 60 to 400.

Voltage Ratings: The C945 transistor has a maximum voltage rating of 50V (Collector-Emitter Voltage, Vceo), while the BC547 transistor has a higher maximum voltage rating of 45V.

Pinout Configuration: The pinout configuration of the C945 transistor and the BC547 transistor is different. While the C945 transistor typically follows the Emitter-Base-Collector (EBC) pinout, the BC547 transistor typically follows the Collector-Base-Emitter (CBE) pinout.

Availability: Both transistors are widely available in the market and are commonly used in various electronic applications. However, the BC547 transistor is more popular and widely used compared to the C945 transistor, which can sometimes be less commonly found.

In overall, the BC547 transistor can be used as a substitute for the C945 transistor in many cases. While there are some differences in their electrical characteristics and pinout configurations, the BC547 transistor has similar functionality and can perform similar tasks as the C945 transistor.


In conclusion, the C945 transistor stands as a versatile electronic component, widely used in low-power amplification and switching applications. Through the exploration of its datasheet, pinout configuration, equivalent alternatives, and diverse uses, this article has provided a comprehensive understanding of the C945 transistor. By referring to the datasheet and understanding its specifications, pinout, and applications, you can confidently incorporate the C945 transistor into your designs, amplifying your ability to create innovative and functional electronic systems.

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  • Is there a recommended storage temperature for the C945 transistor?

    The C945 transistor can be stored within a temperature range of -55°C to +150°C, ensuring its stability and reliability during storage.

  • Can the C945 transistor be used in high-frequency applications?

    The C945 transistor has a transition frequency (ft) of approximately 150MHz, which makes it suitable for low- to moderate-frequency applications. However, it may not be ideal for high-frequency applications where faster switching speeds are required.

  • What is the maximum power dissipation of the C945 transistor?

    The C945 transistor has a maximum power dissipation of 625mW, ensuring it can handle power levels within its specified limits.

Stella Brinkley

Stella Brinkley is a senior electronics engineer with 6 years of experience, specializing in the detailed study of resistor, transistor and package design. Her comprehensive knowledge allows her to drive innovation and excellence in the electronics industry.

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