Answer by jeff · Aug 11, 2011 at 09:32 PM
magnetic information that is stored in analog format, not digital bits of 1 or Zero.
the TAPE (both VHS and BETAMAX back in the day) is pulled out of the plastic case when inserted into the player, a portion of the tape is wrapped around the Video HEAD. The HEAD is actually quite small. The vide HEAD is mounted on a spindle at and angle, so as the tape moves the video information is recorded or played back using most of the width of the video tape. Most VCR have 1, 2 or 4 HEADS so with that being said a 4 HEAD only take 1/4 of a turn of the HEAD motor to read a single frame of video information stored on the tape, thus resulting in a clearer (less static) image. The audio HEAD is not on the spindle but separated and records or plays back the audio information , the audio HEAD uses the outside 'EDGE' of the tape so it doesn't interfere with the video information. If video or audio HEAD is out of alignment you have bad looking video, or the audio is out of sync.
The VCR uses a light or LED that is reflected off a mirror or the tape itself to determine if the tape is in motion and to keep things in sync. The tape counter, the drive motor light sensor all work in conjunction to keep the HEADS in sync (tracing) otherwise over time when your tape stretches your video or audio would degrade.
The drawback of tape is two fold. They wear out! The video and audio heads must be clean or they will ruin the video tape, over time the time will oxidize to the point of no video or audio tracking thus a snowing picture or the picture rolls.
The same method is sill is use for DV cameras , the information is no longer analog but digital, so any read/writing issues can be corrected on the fly.
happy VHS to you..
Answer by kevin · Aug 11, 2011 at 09:11 PM
VHS tapes work because of magnetism. The recording heads on the tape are electromagnets that draws particles of metal onto the tape in patterns set by the TV signals. As the tape goes past the recording heads, the signals are recorded from the electrical signal onto each of the heads of the tape.
Answer by catchatyou · Aug 11, 2011 at 10:04 PM
So basically it's in an analog format (not digital which is the binary code), and it's magnetized (that's why the more you play it, the lower quality it gets).
I definitely don't have the best answer, but I believe it's the shortest/simplest to understand.
Answer by Michael3 · Aug 13, 2011 at 09:46 AM
Hi Jeff, your description of the principle and of the transport mechanism is excellent. Also VHS players had an LF modulator to convert to signals from the video heads into red green and blue analog signals. These are available at the SCART socket, a separate modulator handles the audio fed to the SCART. In the late 1970 most euopean TVs did not have SCART connector, so domestic VHS machines always had an RF modulator to combine the video and audio signals and feed them out on channel 36 . Additionally VHS recorders had a UHF receiver section to receive a TV aerial signal and demodulators to separate and prepare the analog signals fed to the heads when recording off air . The UHF receiver also fed the SCART when not playing tapes. Any signal fed to the SCART socket took presidence over the received off air signal. The quality of pictures via the RF socket is even worse than that from the SCART with max definition of 4 MHz on PAL,about 3.5 on NTSC I believe. see also http://en.wikipedia.org/wiki/SCART
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