Cassette demagnetizer
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A cassette demagnetizer is a device that removes the magnetic charge that is built up from the use of audio cassettes in a cassette deck.
Over time, the passage of magnetically charged cassette tape over the metallic parts of the tape deck will impart a magnetic charge that can impair the ability of subsequent tapes to record accurately. Cassette demagnetizers were developed to remove this charge.
Cassette demagnetizers of the "cassette" type physically resemble a cassette tape shell but contain circuitry to demagnetize the tape heads of the tape deck. Another type of demagnetizer, the "wand" type can demagnetize anything that it is brought into contact with, including the tape heads and capstans. Nakamichi manufactured a "wand" type demagnitizer in the 1980's.
Demagnetizers contain circuitry and require a power source, which is either a battery or a power cord.
A third design(1980s Philips-India ?) consisted of a cassette shell with a head cleaning tape wound on the spools and a disc shaped magnet mounted above the head cleaner tape such that when the play button was activated the head cleaner physically cleaned the head surface and simultaneously made the magnet roatate creating the alternating magnetic field required for demagnetizing(Docp)
