Electrical – How to implement a SCART switch connector

rcascartswitchesvideo

I have some experience with electronics, but no experience with AV. I would love to learn how to do something like the following:

I want to build a little circuit which will do the following:

        Input a SCART(RGB signal) and a Composite RCA connection.
        ----
        Output SCART(RGB signal - passthrough of whatever signal comes in 
        over the Input SCART - or Composite over scart from the composite RCA connection)
        ----
        Switch when flicked left outputs the SCART signal coming in, 
        when flicked right outputs the Composite signal.

My circuit would have a switch which when flicked to the left does a SCART passthrough, when flicked to the right, it flows the composite signal over the SCART output as per the following diagram:

enter image description here

I have a couple of questions to help me solve this problem:

  • I need to know the name of the SCART IN, Composite In breakout board type connector for my circuit
  • How might the switch circuitry be designed

Help in these areas would help give me a starting point of actually building my little circuit!

Best Answer

Small signal relays might be your simplest and cleanest choice here. Reed relays might be an ideal selection.

Selecting double-throw relays makes wiring the system easy - four relays in parallel powered by the same switch. When all are on three route the RGB signal to the output, and the fourth routes the composite nowhere. When all are off three route the RGB signal nowhere, and the fourth routes the composite signal to the output.

schematic

simulate this circuit – Schematic created using CircuitLab

Add more relays to switch more signals as you see fit. You may want to switch the grounds separately, or you may want to join them all together for simplicity. Replacing individual relays with DPDT (Dual Pole Double Throw) would also reduce part count, but these tend to be more available for larger power switching, not small signals.

As for connectors, you will find what you want by dismantling an old VCR.

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