Here I thought S-Video was good

Discussion in 'Video Hardware' started by Howard S Shubs, Aug 7, 2010.

  1. I decided to try connecting my VCR to my eyeTV with an s-video cable.
    Unfortunately, I don't have an s-video cable, so I looked at the
    connector, thought for a minute, then got an old ADB keyboard cable, and
    hooked it up.

    Geez, that looks like crap.

    So I switched back to composite video, using a cable intended for such.

    It still looks like crap. I think it's the video tape itself.
     
    Howard S Shubs, Aug 7, 2010
    #1
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  2. I suppose I could test the impedance with a multimeter... feh, I've
    only got pointy probes. Time to get some clampy probes.

    Yes. I've got other tapes which look much better. This one looks
    exceptionally bad. So be it.
     
    Howard S Shubs, Aug 8, 2010
    #2
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  3. Hm. I thought resistance and impedance were the same. Guess not.
     
    Howard S Shubs, Aug 8, 2010
    #3
  4. That explains the results I got from the grounding shield.
     
    Howard S Shubs, Aug 9, 2010
    #4
  5. Howard S Shubs

    Don Bruder Guest

    Late to the thread, but FYI/FWIW:

    While both resistance and impedance are measured in ohms, and are
    similar in concept, they are ALMOST NEVER equivalent - a cable rated as
    75 ohms impedance is *EXTREMELY* unlikely to have a conductor resistance
    of 75 ohms.

    Y'see, impedance isn't about the "raw ohms" of the conductors being
    used. It's about "At a frequency between X and Y Hz, the cable behaves
    as if it were a Z ohm resistor". It doesn't matter that the individual
    conductors each show a resistance of 0.026 ohms per foot, or whatever -
    it's the interplay of frequency, conductors, insulation, spacing,
    physical layout, the types of connectors on the ends, and about half a
    metric buttload of other factors that all add up to "this is a cable
    with a Z ohm impedance". As a ferinstance, a nominally "75 ohm" cable
    (common for various flavors of co-ax used in TV work) might be 50, 100,
    or even 1000 ohms if you move outside the usual TV signal range. Strip
    back the braid and hook it up with solder, rather than using the usual
    co-ax connectors, and although the RESISTANCE remains the same (or close
    enough that most meters won't be able to show you the difference) you
    might well find that the IMPEDANCE has changed from 75 ohms to 30 - or
    1000 - or "pick-a-random-number".

    Unless you're blessed with the $$ to buy a very specialized meter (The
    ones that cable TV installers tote around can do it, but I'm told that
    the price tags on those babies would make a decent down-payment on a
    house) it's safe to say that you're a lot better off just going out and
    getting a pre-made cable intended for the purpose - You'll save yourself
    *MUCH* headache.
     
    Don Bruder, Aug 23, 2010
    #5
  6. Thanks. At this point, I'm finished. Ran out of tapes worth
    converting, I think.
     
    Howard S Shubs, Aug 23, 2010
    #6
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