The pull switch has a keyring interface that can be connected to various grips such as a handle-bar grip. The switch is activated by the client grasping the grip and pulling. The base of the switch is usually secured to a table by clamps. This switch is required to replace an existing unit which is no longer available and does not use standard parts for repair. The switch is a normally open contact. The switch is connected to another device through a microphone jack that connects to the actual switch contacts. The switch is intended for low voltage applications. The switch body must be strong enough to withstand substantial pull applied by the client. Pictures of the existing device are available from Jeff Kernan.
A design has been developed that uses a commercially available switch (approximately $2) as the internal switching element. This pushbutton switch is activated when a spring-loaded lever is pulled against the switch plunger. Positive stops on the lever prevent excessive force to be applied to the switch. Pull force to actuate the switch can be modified by the choice of a spring that the lever must compress. The prototype supplied to Hills and Dales is now in daily use and they have reported that it functions well.
RCRV designer is Russell Schuchmann, and was requested by Jeff Kernan, Hills & Dales, Dubuque email@example.com. The project was begun Sep 12, 2003 and completed Dec 11, 2003.
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Pull switch plans