My grandfather worked at Philco in the 1950s working on some of these. We have a bunch of family pictures of one of the prototypes he built in college in, like,

My grandfather worked at Philco in the 1950s working on some of these. We have a bunch of family pictures of one of the prototypes he built in college in, like, the 1940s? I think? My understanding is that he worked on audio circuitry back at the time.