MadSci Network: Engineering

Re: How does a VCR work? Why does a VCR have a spinning head?

Date: Tue Apr 7 10:18:40 1998
Posted By: Gus Calabrese aka puppet boy, Design Engineer
Area of science: Engineering
ID: 891365829.Eg

A VCR uses a cartridge containing tape.  When you insert the catridge,
the VCR grabs the tape and wraps it around the read head.  The tape is
positioned at an angle to the head so that as the head spins it sweeps
across the tape at an angle somewhere between the horizontal flow of the
tape and a vertical line from the bottom edge of the tape to the top of
the tape.  This approach lets the head use nearly the entire surface of
the tape and lets the read portion of the head move at a greater speed
across the tape than the speed of the tape itself would cause.  When you
pause the VCR and look at frozen video, the tape is not moving and the
head is sweeping across on portion of the tape over and over.

The same principles apply to recording video to the tape.

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