On Wed, 30 May 2012, Tim Wescott wrote:

Answering Robb's question made me think of a very mild puzzler:

Can you think of a way to connect up an octal tube socket so that no
matter what orientation a pair of crystals is put into it you'll still
have two switchable crystals (no forcing pins allowed -- only schemes
where the crystal goes into receptacle 1 & 3, 2 & 4, etc.).

And, after you exercise the dozen brain cells that it takes to answer
that question -- did anyone do it in a production radio, or publish it in
a magazine, that you know of?

I don't know, but it seems like the sort of thing you'd find in a Hints &
Kinks in QST, or filler in CQ (they had a book issued in the fifties that
collected little bits, I can almost picture almost picture something like
this in there).

Michael VE2BVW