Here is another example of using a CD4051 multiplexer, or more accurately a pair of CD4051s in parallel. I had lifted much of the core logic and circuits from Dave Jones designs. Again these are old designs offered from a historical perspective.
CMOS analog multiplexers were frequently used at the ETC for various purposes. Here I thought I would present a circuit I borrowed from a Dave Jones design, and slightly modified it, to build a black burst generator.
This was an early Dave Jones keyer. Rich Brewster documented and built it. We referred to this as the black box keyer because it was in a black box. This keyer moved around a bit, at times it was at the center, at times it was at Ralph's studio. I first used this keyer as a student working at the ETC in the converted photo lab studio (at that point the Center was still on Court Street in Binghamton). Years later when I was working for the TV center I lobbied to install it back into the ETC studio.