Examples of widely used analog devices include telephones, record players and tape recorders. An analog device is a piece of hardware that simulates the physical quantities of a variable signal.
Many older telephone systems are digital and analog hybrids. The digital portion is used to translate phone numbers into data that allows telephone systems to route the phone calls to their destinations. The analog portion of the telephone, however, converts the audio part of the phone call into electronic pulses that are passed along the telephone line, where they are reconverted into the audio that the other user hears.
The conversion of audio into transmittable signals is also the key behind both record players and tape recorders. For record players, the audio is converted into physical bumps and grooves on a record's surface. These physical variations are picked up by a needle on a record player and passed onto an amplified diaphragm that vibrates, recreating the audio that was recorded.
Tape recorders work in much the same way, converting audio into quantities of magnetism that is recorded onto magnetic tape. When the tape is played back, the magnetic data is converted to electrical current sent to a set of speakers, where the changing vibration of the speakers recreate the recorded sounds.