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Switch for video? — Parallax Forums

Switch for video?

FranklinFranklin Posts: 4,747
edited 2007-01-23 03:57 in General Discussion
I would like to create a project that would use an rfid card and timer to limit TV usage.
What type of device would I want to make and break the video line to the TV?
Turning power off to the TV would erase the channel programming so I thought I could just interrupt the signal.

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- Stephen

Comments

  • Mike GreenMike Green Posts: 23,101
    edited 2007-01-23 02:42
    There are antenna switches that you can probably still get at Radio Shack or even large hardware stores for switching the antenna of a TV between two sources. These generally have a slider that moves over a significant distance, maybe 1/2 inch. You could set up a servo and one of these switches in a metal box (for shielding - and connect the outer box to the metal box containing the RF switch). As the servo moved from one position to another about 180 degrees apart, a piece of piano wire connecting the servo arm to the switch would slide it from one position to the other. The reason for using this particular type of switch is that the two sides of the switch are well isolated from each other so virtually no signal will get across from one position to the other without the switch being closed.
  • Kevin WoodKevin Wood Posts: 1,266
    edited 2007-01-23 03:02
    What about using a video overlay generator to print messages on the screen?

    Or as more time passed, it could cover the screen with an increasing number of blocks.
  • Brian CarpenterBrian Carpenter Posts: 728
    edited 2007-01-23 03:19
    Any switch will work on the input signal. Maybe BEAN can jump in here but if you use a transistor to pass the signal through when tv access is permitted and then drop the power fron the transistor and signal is gone.

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    It's Only A Stupid Question If You Have Not Googled It First!!
  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 23,514
    edited 2007-01-23 03:29
    Overlay generators are used with baseband video — not RF. You mentioned a "video line", from which Mike inferred (correctly I'm betting) that you meant the antenna (RF) cable. If that's the case, his solution is a good one, because it's mechanical and eliminates the (potentially tricky) messing with the actual VHF/UHF RF signals.

    -Phil
  • FranklinFranklin Posts: 4,747
    edited 2007-01-23 03:57
    Well, I'm thinking it's RF (it will be from a dish network box I don't have yet.)

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    - Stephen
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