How the ¹/₄ in. Jack Works

  I suppose that this doesn't really belong in the 'Physics' section; it's a little too non-technical to fall under the category of a physics description.  There's really no better place to put it, though, so I'll just put it here.

  The ¹/₄ in. jack works by having a series of metal springs push up against the side of the ¹/₄ in. plug, making electrical contact with the different segments of the plug.  This diagram shows the two metal springs that we use in this circuit; the width of the jack, relative to the width of the plug, is greatly exaggerated for clarity.