A simple device to turn an HDMI connection off without unplugging the cable…

I have a screen on my desk that I usually use for my second computer. But sometimes it would make more sense to use it as an additional screen on my main machine. The problem is: When I keep it plugged in and just switch the input on the screen, the main computer still sees it and expands its desktop to that screen. Since I also didnt want to unplug the HDMI all the time I needed a simple solution: I read through the HDMI Specification and found that disconnecting the 5V line and the Hot Plug Detection line should be enough.

I designed a simple circuit that routes the high speed lines directly between two HDMI plugs and just those two lines through an ordinary switch. I also added an LED as a status light and got the boards manufactured. Today they arrived and they work perfectly!