I have this for Sample and Hold effects. Though I have yet to build a really good one.
Here are a bunch of sketches of S&H ideas that I have been testing.
This is the Maestro FSH-1.
This uses a 7555 timer for a clock in an attempt to get as short and sharp a clock pulse as possible.
This is Ray Wilsons Sample and Hold from Musicfromouterspace.com
Here’s an idea from the app notes of the 13600. This one worked pretty well.
This idea came from the Diystompbox.com forum