First off, since this is my first post to the forum, I feel I should probably give a little information about myself...
My name is Doug, and electronics is my hobby. I have been playing with digital electronics for several years, and wouldn't consider myself quite a newbie. But since I know absolutely nothing about analog signaling I chose to post here. My profession is in the legal field. Which lends itself well to digital electronics (both deal with logic). I have my own electronics / retro-tech website, and upload my own videos to YouTube, where I have showed several of my electronics and software projects.
Now, for the meat of the question. I'm working on a project where I need to be able to select between two separate composite video signals, and do so without swapping connectors. I have looked at ICs such as the 74HC4051 and 74HC4052 (more ideal, as I do not need 8 signals), and I do not believe that it will work, since there is a small amount of negative voltage in a composite signal. I suppose it would really depend on the tolerance of the television, since several other composite signals I've played with would work fine on a modern LCD but not at all on an older CRT.
However, I then got to thinking about using a Flip-Flop and two MOSFETs as gates. I've posted a schematic below detailing my idea. The theory of operation is that at reset the flip-flop Q is cleared to Logic 0, and the !Q is set to 1. This turns on Q1, and allows the Composite Video #2 to display. When the CS line is toggled, this changes the state of Q to 1, and !Q to 0, effectively turning off Q1 and turning on Q2. Effectively a simple switch allowing you to swap gates through software.
The reason I chose a MOSFET is because of the low resistance in the open state. However, I still do not believe that this will work. The reason why I believe it will not work is because my understanding of a MOSFET is that it still acts as a Diode, and as such would not be able to generate the negative voltage level. Again, I know very little about analog signaling.
Does anyone have an example circuit they might be able to share, or some reading material to point me towards? My Google Kung Fu has left me without. I do not mind doing the research. But I have to know the direct to get to it.