## 2SC2240 NPN Epitaxial Silicon Transistor The **2SC2240** is a popular high-voltage, low-noise NPN transistor primarily designed for audio frequency (AF) amplification. It is highly regarded in the audiophile community for its exceptional linearity and low noise floor. ### 1. Key Technical Specifications | Parameter | Symbol | Rating | Unit | | :--- | :---: | :---: | :---: | | Collector-Base Voltage | $V_{CBO}$ | 120 | V | | Collector-Emitter Voltage | $V_{CEO}$ | 120 | V | | Emitter-Base Voltage | $V_{EBO}$ | 5 | V | | Collector Current | $I_C$ | 100 | mA | | Collector Power Dissipation | $P_C$ | 300 | mW | | DC Current Gain | $h_{FE}$ | 200 to 700 | - | | Transition Frequency | $f_T$ | 100 | MHz | --- ### 2. Main Characteristics * **Low Noise:** It features a very low noise figure (typically $NF = 2.0\text{ dB}$ or less), making it ideal for the first stage of pre-amplifiers or phono stages. * **High Voltage:** With a $V_{CEO}$ of 120V, it can be used in circuits with relatively high voltage rails without the risk of breakdown. * **High Linearity:** The current gain ($h_{FE}$) remains stable across a range of collector currents, ensuring low distortion in audio signals. * **Complementary Pair:** It is often paired with the **2SA970** (PNP), which has matching characteristics for push-pull circuit designs. --- ### 3. Pinout and Package The 2SC2240 usually comes in a **TO-92** plastic package. Looking at the flat side with the leads pointing down, the pin configuration is: 1. **Emitter (E)** 2. **Collector (C)** 3. **Base (B)** --- ### 4. Common Applications 1. **Audio Pre-amplifiers:** Used in the input stages where maintaining a clean signal is critical. 2. **Phono Equalizers:** Excellent for boosting low-level signals from vinyl turntables. 3. **Constant Current Sources:** Due to its stability and voltage rating. 4. **Driver Stages:** Used in small power amplifiers to drive larger power transistors. --- ### 5. Classification of $h_{FE}$ The 2SC2240 is usually sorted into two gain categories, marked on the component: * **GR (Green):** 200 ~ 400 * **BL (Blue):** 350 ~ 700