Another example of a reflex circuit is at http://www.sm0vpo.com/rx/reflex_rx.htm . Perhaps the most famous reflex circuits came from Sir Douglas Hall in a series of circuits in Radio Constructor back in the 1960s and early 1970s. Some of these are collected at http://www.spontaflex.free-online.co.uk/ . Sir Douglas was a UK overseas diplomat and a very nice gentleman. One of my old school friends lived in the same Devon village and visited him to try some of his prototypes.