Precision actuation switch

A switch, mounted adjacent to a carriage member for sensing the end of tape on a reversible tape transport of the type having a reel which alternately serves as supply and take up reel rotatably mounted on a carriage member which moves toward and away from a rotatably driven capstan, to facilitate reversing direction of the capstan in response to the actuation thereof, said switch, comprising:

• a housing having a longitudinal axis;
• a pair of electrical contacts positioned within said housing adjacent to the axis and adapted to be connected to circuitry means;
• an actuator means adapted to be operable along the axis between said contacts, said actuator means including a plunger having one end extending from said housing and having screw threads extending substantially over its length, and a yoke which has a base with a threaded aperture adapted to receive said plunger whereby the length of said plunger extending from said housing is precisely adjustable by the rotation of said plunger;
• a shorting means positioned within said housing and adapted to be elastically compressible relative to said actuator means and to be translatable by said actuator means to engage said electrical contacts, said shorting means including a conductive compression spring adapted to be positioned having the free length thereof partially compressed within said yoke, whereby a predetermined force will be required to further compress said spring to facilitate positive electrical conduction upon abuttment with said electrical contacts;
• and
• biasing means to urge said shorting means away from said contacts whereby the switch will be actuated by the position of the plunger of said actuator means corresponding to a position of the member.