A 16 port automatic Scart switch - powered by 5v micro USB PSU, automatically switches to the last powered input.

The switch is particularly funny about the signal level of the sync input (which is what it uses to determine a 'live' scart port). Lots of consoles that work fine plugged in to a screen directly with scart fail to work when plugged in via the Hydra.

Turns out that a lot of these systems are outputting >1 volt on the Scart pin 20 (video sync), and need to be brought back down to <= 1volt. What a pain.....

[Update 2022] - Never got around to getting anything working with this; it is FAR too picky about what works and what doesn't. The similar gscartsw is a much better product and worked with everything that the Hydra didn't.