Apologies for total building n00b question here, but would a mixer based on the dirty schematic be possible to make that doesnt heavily distort signals? Looking for something cheap, simple abd portable for live mixing and blending. Thanks!
Not really. The reason the dirty mixer is cheap and small is because it distorts the signals. Mixing composite video without distortion is a whole different ballgame.
The reason the dirty mixer distorts signals is because it doesn’t do anything special about the video sync. For clean mixing, both inputs need to be in sync before mixing. You can actually do clean mixing with a dirty mixer, as long as your sources are perfectly in sync. But getting video signals in sync isn’t always easy. Some devices (some old pro gear, some security cameras) have a “genlock” input which can be used for syncing so those would probably mix cleanly with a dirty mixer, if synced. Otherwise you need something called a time base corrector (TBC) to synchronize your signals before mixing. Most “real” video mixers have TBCs built into them, hence why they can cleanly mix signals.