Uploaded December 2016 | Updated September 2026, 1 day ago
A transistor is a semiconductor device used to amplify or switch electronic signals and electrical power. It is composed of semiconductor material usually with at least three terminals for connection to an external circuit. A voltage or current applied to one pair of the transistor's terminals controls the current through another pair of terminals. Because the controlled (output) power can be higher than the controlling (input) power, a transistor can amplify a signal. Today, some transistors are packaged individually, but many more are found embedded in integrated circuits. Wikipedia
A transistor is a semiconductor device used to amplify or switch electronic signals and electrical power. It is composed of semiconductor material usually with at least three terminals for connection to an external circuit. A voltage or current applied to one pair of the transistor's terminals controls the current through another pair of terminals. Because the controlled (output) power can be higher than the controlling (input) power, a transistor can amplify a signal. Today, some transistors are packaged individually, but many more are found embedded in integrated circuits. Wikipedia




![Edison cylinder phonograph model C
Phonograph cylinders are the earliest commercial medium for recording and reproducing sound. Commonly known simply as records in their era of greatest popularity (c. 1896–1915), these hollow cylindrical objects have an audio recording engraved on the outside surface, which can be reproduced when they are played on a mechanical cylinder phonograph. In the 1910s, the competing disc record system triumphed in the marketplace to become the dominant commercial audio medium. The phonograph was invented by Thomas Edison and his team on July 18, 1877. His first successful recording and reproduction of intelligible sounds, achieved early in the following December, used a thin sheet of tin foil wrapped around a hand-cranked grooved metal cylinder.[1] Tin foil was not a practical recording medium for either commercial or artistic purposes and the crude hand-cranked phonograph was only marketed as a novelty, to little or no profit. Edison moved on to developing a practical incandescent electric light and the next improvements to sound recording technology were made by others.
Following seven years of research and experimentation at their Volta Laboratory, Charles Sumner Tainter, Alexander Graham Bell and Chichester Bell introduced wax as the recording medium and engraving, rather than indenting, as the recording method. In 1887, their Graphophone system, which recorded dictation on disposable cardboard tubes with a thin wax coating, was being put to the test of practical use by official reporters of the US Congress, with commercial units later being produced by the Dictaphone Corporation. After this system was demonstrated to Edisons representatives, Edison quickly resumed work on the phonograph. He settled on a thicker all-wax cylinder, the surface of which could be repeatedly shaved down for reuse. Both the Graphophone and Edisons Perfected Phonograph were commercialized in 1888. Eventually, a patent-sharing agreement was signed and the wax-coated cardboard tubes were abandoned in favor of Edisons all-wax cylinders as an interchangeable standard format. Wikipedia Edison cylinder phonograph model C](https://i.ytimg.com/vi/vCZQ7n-6TTo/mqdefault.jpg)





