Magnetic recording dates back to 1898, when the telegraphone wire-recording machine was invented by the Danish inventor Valdemar Poulsen. Unfortunately, this machine was poor in quality because it did not contain the proper amplifiers and wire, so magnetic recording was delayed for several decades. Present-day recording involves using tape rather than wire.
A tape recorder consists of several motors that transfer the tape from one reel to another. Other motors perform the functions of fast-forward and rewind, and provide torque for the take-up reel during playback. Most machines have three heads, one for playback, one for erasure, and one for recording.
The tape itself is usually made of plastic material--cellulose acetate or polyester--and commonly 1/4" wide for home use. It is coated on one side with so many iron oxide particles that one inch of tape contains nearly one trillion particles! Several different sized reels are available, as well as cartridges and cassettes, which require special machines to operate them.
Magnetic recording is superior to disc recording because
it can easily be edited. Tape can be cut and spliced with ease.
In addition, tape can be reused indefinitely by erasing and re-recording.
Unfortunately, tape recordings cannot be mass produced inexpensively like
records can. Discs can easily be pressed by mechanical means, but
the many feet of tape that comprise a reel must be recorded manually.
On to Magnetic Recording: How a Tape Recording Machine Works