This project makes up a small PCB that you can embed into pretty much any Retro system that uses CHROMA + LUMA (Svideo) to create its output. This amp can be configured to filter, or filter and amplify the signal - and it will also generate a perfectly in-spec CVBS (Composite) signal without injecting any interference onto the other signals.
The PCB uses the FMS6400 IC at U1 - and while these are older and out of production, there are many to be had on eBay or AliExpress.
Datasheet for the IC: https://static6.arrow.com/aropdfconversion/7fe50da04e1ba81a06ef8d061fd01bb64574320b/fms6400.pdf
You need +5v and LUMA and CHROMA that are somewhere in the ballpark of correctly generated. This board will take those signals and spit out filtered / corrected signals that can be sent on to a TV or Projector, most anything that accepts SVideo or Composite.
I originally put this together to give my Atari XE a slightly better quality of video and to generate a composite out without leaking LUMA everywhere. Have fun!