What is 2SC1815 NPN transistor? This article will discuss the 2SC1815 transistor’s features, pinout, specifications, applications, comparisons, and more.

Catalog

2SC1815 Transistor Overview

The 2SC1815 is a silicon NPN bipolar junction transistor manufactured by Central Semiconductor using a reliable epitaxial planar process. It is widely used for general-purpose low-power amplification and switching. With voltage ratings of 50V VCEO and 60V VCBO, a maximum collector current of 150mA, and power dissipation around 400mW, it performs well in small-signal applications. Its high current-gain range and transition frequency of about 80MHz make it suitable for audio stages, preamplifiers, and low-noise circuits.

Because of its stable gain, low noise, and TO-92 package, the 2SC1815 is commonly chosen for hobby electronics, analog designs, and driver stages that require consistent, clean signal amplification. It is not intended for high-power or high-current loads, but excels in compact, efficient low-power circuits where reliability matters.

If you are interested in purchasing the 2SC1815, feel free to contact us for pricing and availability.

2SC1815 Transistor CAD Models

2SC1815 Pinout Configuration

Alternatives & Equivalents

• 2N3904

• BC547

• BC548

• BC549

• 2N2222 / PN2222

• 2N4401

• 2N5088

• 2N5551

2SC1815 Transistor Specifications

2SC1815 Transistor Application Circuit

C1815 Audio Amplifier Circuit

This circuit demonstrates a simple audio amplifier using the 2SC1815 NPN transistor. The audio input signal is fed into the transistor’s base, optionally through a coupling capacitor to block any unwanted DC offset. Biasing resistors R3 (2.2 kΩ) and R4 (1 kΩ) set the correct operating point for the transistor, ensuring it functions in its active (linear) region for clean amplification. When the small audio signal enters the base, the transistor modulates a larger current flowing from the supply through R1 (100 Ω) and the transistor’s collector-emitter path.

The amplified output is taken through C1 (10 µF), which filters DC and passes only the amplified AC audio signal to the 8-ohm speaker. Resistor R2 (10 Ω) stabilizes current and prevents distortion. Overall, the 2SC1815 acts as a current amplifier, producing a stronger copy of the weak audio input, suitable for driving a small speaker.

2SC1815 Biasing & Amplification Example

The second diagram is a simplified small-signal amplifier using the 2SC1815 with a 5V supply. The input signal is injected at the base through R1 (1 kΩ), which limits base current. Resistors R2 (120 kΩ) and R3 (2 kΩ) create a voltage-divider biasing network, establishing a stable base voltage so the transistor remains properly biased even when the input varies. Once biased, the transistor operates as a linear amplifier, where a small base current change produces a much larger variation in collector current.

The output is taken from the transistor’s collector. As the base receives the input waveform, the collector voltage swings in response, forming an amplified version of the signal. This design is commonly used in preamplifiers, sensor signal conditioning, or low-level audio stages because the 2SC1815 offers good gain, low noise, and stable operation at low voltages.

2SC1815 Wide Applications

• Audio preamplifiers

• Low-noise signal amplification

• General-purpose switching

• Small audio amplifier stages

• Sensor signal conditioning

• Oscillator circuits

• Pulse and waveform shaping circuits

• Radio frequency (RF) circuits (low-power)

• Intercom and microphone amplifiers

• DIY electronics projects

• Logic signal level shifting

• Small motor or relay driver (with proper interface)

• LED driving and control

• Voltage regulator feedback stages

• Alarm and buzzer driver circuits

• Analog input stages for microcontrollers

• Detector and demodulator circuits

• Hobby radio transmitter/receiver stages

• Tone control circuits

Comparison: 2SC1815 vs 2SC2240

2SC1815 Mechanical Dimensions

Manufacturer

Central Semiconductor Corp is a popular manufacturer. They are known for producing high-quality discrete semiconductors, including diodes, transistors, rectifiers, and protection devices for commercial, industrial, and high-reliability applications. Central Semiconductor is recognized for its advanced wafer processing, rigorous quality control, RoHS-compliant manufacturing, and expertise in supporting aerospace, medical, telecommunications, and power management sectors with precision, small-signal, and power devices designed for demanding performance and reliability standards.