Cassette adapter

A cassette adapter, also called a car connecting pack, is a device that allows audio output from a different source to be played through sound systems with a cassette deck. It is primarily used for outputting audio from mobile phones, portable media players or portable CD players to car stereos with a cassette deck but without auxiliary (aux) ports built into their sound systems.

The cassette adapter is a "dummy" tapeless Compact Cassette. Instead of having magnetic tape, the adapter uses (typically) a writing tape head similar to the reading tape head on a cassette deck. The adapter's head connects to an audio source terminal using a stereo minijack connector cord, and the incoming electrical signal is converted into a magnetic signal to allow it to be read by the deck's head as if it were a normal cassette tape. One-way gears within the cassette simulate tape movement from reel to reel, to ensure that the deck does not auto-reverse.