Record players are traditional sound systems in which rotating records cause a stylus to vibrate and the vibrations are amplified acoustically or electronically. Traditionally record changers are mostly provided in form of consumer phonographs. Phonograph reproduces sound by means of a stylus in contact with a grooved rotating disc. They typically had a extended central spindle that the records were stacked on, and an extra arm designed to hold the stack steady and detect the width of the record. The limited playing time of 78 rpm a record player/ changer provides an analogue sound recording medium: a flat disc rotating at a constant angular velocity, with inscribed spiral grooves in which a stylus or needle rides. The disc is almost always engraved that led to the development of record changers, which allowed stacks of several records to be loaded on a spindle and automatically played in sequence.
