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Making a new video switch box, suggestion please

Discussion in 'Electronic Projects Design/Ideas/Reviews' started by wilykat, Dec 26, 2017.

  1. wilykat

    wilykat Member

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    I have a bunch of game consoles and I love to play em. Those that aren't capable of component or HDMI are connected via composite and currently I have 22 game consoles (a couple more in 2018 is likely)

    I thought I'd redo the switch box in solid state and use Arduino to connect with a small LCD displaying the current system and controlling the analog switch. One example is CBT3244AD as used by this site: https://www.engadget.com/2007/03/13/how-to-make-a-solid-state-a-v-switcher/ I can easily make one that goes up to 32 devices to one TV using a few decoders like 74138 (output are high unless it's selected and enable is also correct so only the CBT3244AD that has low on enable are active while rest should be open)

    But there's an issue of ground. With the mechanical switch, it was easy to isolate ground so only the current system were connected by ground to TV while the rest of the system and oh some 200 feet worth of wires aren't connected and not acting like inadvertent antenna.

    I am not sure how the analog chip would handle ground switching. If I connected ground from console to the above analog switch IC, would it still be isolated if it's not active? Or is there a better idea? A better behaved analog switch chip? I've looked into isolation transformer for video and unless I looked at the wrong stuff, $80 for one is pricey! Using 3pst or 4pst relay is also not cheap and they do take up a lot of space.
     
  2. dknguyen

    dknguyen Well-Known Member

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    Datasheets for analog switches always tell you what they will do. Have you tried looking at any before asking this question? It's quite clear from Figure 1 of the datasheet for CBT3244AD
     
  3. ronsimpson

    ronsimpson Well-Known Member Most Helpful Member

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    Sounds like a full time job!
     
  4. dave

    Dave New Member

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  5. dknguyen

    dknguyen Well-Known Member

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    Oh, BTW, I would consider analog multiplexers. Should help do away with a lot of decoders and junk. The ADG732, for example.
     
  6. AnalogKid

    AnalogKid Well-Known Member

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    Generally speaking, mux chips (video, audio, whatever) do not switch the ground, and require that all signal have a common signal ground potential. Maxim makes some nice parts; they are the basis for many video mux boxes on ebay. With proper decoupling and a little input filtering, is should not be the case that a bunch of floating connections fro the circuit GND act as noise antennae. I've dealt with large video switching arrays in TV stations and not had a problem.

    ak
     

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