The title says it all. This is the circuit that is built into the Kustom 150 tuck and roll heads from the early 70's. It's just a fantastic tremolo! Swampy, greasy, but can also be dialed in with the intensity control to be subtle and musical. And you can blend in Vibrato as well, which makes it really unique. Yes, it is exactly that "Born on a Bayou" sound. It would be awesome if somebody reverse-engineered this into a modern stompbox:
https://drive.google.com/file/d/1uZWRTByEbNL4LQCZ0LYVIo_NmSh7So8M/preview?pli=1&rm=demo (https://drive.google.com/file/d/1uZWRTByEbNL4LQCZ0LYVIo_NmSh7So8M/preview?pli=1&rm=demo)
Would be pretty sick!
Here are some additional resources, if somebody wants to tackle this...
A downloadable and printable K150 schematic is attached, including the FX boards and vib/trem foot switch.
Patent for Kustom FX boards, with block diagram and description of tremolo and vibrato will be posted in next message (I hit the upload file limit.)
Discussion elsewhere about this same topic: https://www.diystompboxes.com/smfforum/index.php?topic=100981.msg891891#msg891891
Patent attached.