Variable scale rotary switch

A variable rotary switch assembly, comprising:

• a first knob adapted to rotate about a vertical axis, said first knob having a first point of origin that rotates into a plurality of first radial positions about said vertical axis, said first knob being adapted to move from a first vertical position to a second vertical position;
• a second knob within said first knob, said second knob being adapted to rotate about said vertical axis relative to said first knob, said second knob having a second point of origin that rotates into a plurality of second radial positions about said vertical axis, said second knob being adapted to move from a third vertical position to a fourth vertical position;
• a hollow first shaft attached to said first knob that rotates with said first knob about said vertical axis, said first shaft extending along said vertical axis;
• a second shaft attached to said second knob that rotates with said second knob about said vertical axis, said second shaft being coaxial with said first shaft;
• first sensor means operatively connected to said first shaft for determining said first radial position of said first point of origin of said first knob;
• second sensor means operatively connected to said second shaft for determining said second radial position of said second point of origin of said second knob;
• third sensor means operatively connected to said first knob for sensing when said first knob is in said first and second vertical positions;
• fourth sensor means operatively connected to said second knob for sensing when said second knob is in said third and fourth vertical positions;
• and,
• magnetic clutch means operatively connected to said first shaft and said first sensor for engaging said first shaft when said first point of origin of said first knob is in a predetermined first radial position.