Available as an assembled Module and as a DIY project.
This Module is currently available.
Triple 2-to-1 Video Multiplexer
SHUTTER is a Video Rate, Triple Luma Switcher which allows users to switch Luma signals based on the brightness difference of the Switcher inputs.
Three sets of 2-to-1 multiplexer circuits are provided which allows users to switch two full color RGB-sets, or six different B/W images independently.
Multiple SHUTTER modules may be daisy-chained to switch between more than 2-RGB sets.
*Current Consumption has been verified with the Joranalogue Test 3 V/mA Meter.
https://foxinghour.com/products/shutter-triple-2-1-video-multiplexer
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These merchants probably sell this module. Huh?