How Does a VCR Work?
A VCR must deal with the 800-foot tape, and read the signals off the tape and convert them to signals that a TV can understand. To do this, two recording heads are mounted on a rotating drum and tilted with respect to the tape. Each pass of the VCR’s rotating head reads or writes the data for one field of the television image. The two heads alternate, each one reading or writing every other band. The control track on the tape tells the VCR what format the tape was recorded in, how fast to pull the tape past the drum, and gets the heads lined up with the bands of information. The head rotates at 1,800 RPM or 30 revolutions per second. The tape has to take a tortuous path inside the VCR to keep the tape wrapping around the rotating head — the VCR extracts a long piece of tape from the cassette and wraps it around numerous drums, rollers, and heads to keep it moving in order to play the tape.
