4148

4148 is most commonly used to refer to the 1N4148, a widely used small-signal silicon switching diode. Introduced in the 1960s and produced by many manufacturers, the 1N4148 has become a standard component for high-speed switching and signal rectification in a broad range of electronic equipment. The term 4148 is often used as shorthand in catalogs and schematics to denote this diode or its equivalents.

Electrical characteristics of the 1N4148 include a repetitive peak reverse voltage of about 100 volts and an average forward current around 300 milliamps. It is designed for fast switching, with a reverse-recovery time on the order of a few nanoseconds. The forward voltage drop is typically around 0.6 to 0.7 volts at rated current, and the junction capacitance is small enough to support high-speed operation in many circuits. The device is commonly available in a glass DO-35 axial package, with surface-mount variants marketed under LL4148 and similar designations to suit modern production methods.

Applications for the 1N4148 include general-purpose high-speed switching, signal rectification in small-signal and logic circuits, clamping and protection roles, and educational applications where a reliable, easy-to-find diode is needed. Its combination of speed, low cost, and wide availability has contributed to its enduring popularity in both professional and hobbyist electronics.

In common usage, 4148 almost always refers to this diode; outside electronics, the number can appear in various codes or model numbers unrelated to the component.