2n4

2n4 is a designation used for a variety of electronic components, most commonly referring to a type of semiconductor device. The "2n" prefix typically indicates a germanium transistor, a type of bipolar junction transistor (BJT) that was prevalent in early transistor technology. The "4" following the prefix is a specific part number, differentiating it from other transistors in the 2n series. Germanium transistors like the 2n4 were known for their lower voltage operation and different temperature characteristics compared to later silicon transistors. They were widely used in applications such as amplification and switching circuits during the mid-20th century.

While the 2n4 designation most often points to a germanium transistor, the specific characteristics and applications can vary slightly depending on the manufacturer and the exact sub-designation. Different manufacturers might have produced their own versions of a 2n4 transistor with minor variations in performance parameters. Due to the obsolescence of germanium technology in favor of silicon, the original 2n4 transistors are now rarely manufactured and are primarily of historical interest or sought after by collectors and enthusiasts of vintage electronics. Modern electronic designs almost exclusively utilize silicon-based transistors.