Abstract: A diaphragm switch includes a housing having an interior space and a substrate in the housing supporting an electrical contact. A flexible membrane has opposite first and second surfaces, the first surface being electrically conductive. The membrane is mounted in the housing proximate the substrate with the first surface minutely spaced apart from the electrical contact. An activation pressure in the housing is communicated to the second surface of the membrane whereby deformation of the flexible membrane caused by the activation pressure closes the minute spacing between the electrically conductive first surface and the electrical contact, thereby completing an electrical circuit. A leakage path is operatively associated with the membrane between the first and second surfaces to equalize static pressure on both surfaces, whereby the flexible membrane is not deformed and the circuit is not complete in the absence of the activation pressure.

Abstract: A watertight, immersion proof musical pacifier includes a mouthpiece including a faceguard having a central opening defining an air passage to an integral sealed housing. A nipple has an interior space. A plug sealingly mounts the nipple to the mouthpiece with the interior space in communication with the housing through the air passage. A switch-actuated sound generating circuit disposed in the housing controllably reproduces audio signals. A pressure sensitive switch normally closes the air passage. The switch electrically actuates the sound generating circuit in response to pressure generated in the nipple. An air leakage path between the nipple interior space and the housing to maintain static pressure equilibrium between the nipple interior space and the housing.

Abstract: An electronic thumbwheel switch includes an up/down counter for storing a thumbwheel count value. A display device is coupled to the up/down counter for displaying the count value. A manual input switch is coupled to the up/down counter for selecting a desired count value to be displayed on the display device. An interface circuit is coupled to the up/down counter and includes a data bus buffer for developing an output representing the stored numeric value and a logic circuit and data bus for loading a numeric value received from an external source into the up/down counter for display on the display device.