Abstract: A method is disclosed for simultaneously producing a plurality of capacitive electroacoustic transducers. The method comprises forming a plurality of electrically insulative substrates by cutting circular slots to an insulating wafer. Each slot is interrupted by at least two tabs connecting a circular area with the remainder of the wafer. The conductive diaphragms are supported on diaphragm mounting rings disposed upon the substrate, spaced from a first electrode. The mounting rings space the diaphragm from the electrode to define a capacitor operative to convert electrical and acoustical signals.

Abstract: A method of producing a capacitive electroacoustic transducer comprising the initial step forming a substrate having top and bottom surfaces each having a periphery thereof. A first electrode of the transducer is formed upon a portion of the top surface of the substrate. A diaphragm mounting ring of a conductive material is disposed about the periphery of the top surface and separated from the first electrode, and is sized to be thicker than the first electrode by a desired electrode separation distance. The diaphragm mounting ring is characterized by physical dimensions thereof. A compensation ring is aligned with the diaphragm mounting ring upon the bottom surface, and is formed of the same conductive material as the diaphragm mounting ring. The compensation ring is sized to have the same physical dimensions as the diaphragm mounting ring.

Abstract: A capacitive electroacoustic transducer which includes an electrically insulative substrate, a layer of conductive material disposed on a portion of a top surface of the substrate forming a first electrode of the transducer, a conductive diaphragm forming a second electrode of the transducer which is deflectable in relation to the first electrode, and a structure for electrically and physically separating the first and second electrodes in spaced relationship so as to constitute a capacitor. This transducer exhibits a high degree of thermal stability partly due to the substrate and diaphragm being made of materials having closely matched thermal expansion coefficients. This feature ensures that the tension in the diaphragm stays consistent even with varying temperatures, thereby maintaining a constant transducer sensitivity. In addition, the distance separating the first and second electrodes is minimized so as to create a short thermal expansion path.

Abstract: A hermetically sealed condenser microphone including an outer sealing diaphragm hermetically sealing an electroacoustic transducer within a case from the outside environment. The sealing diaphragm passes sound undiminished through an underlying intervening air space to a second active diaphragm of the electroacoustic transducer. Specifically, the case has a hollow interior, a sealed end and an open end. The electroacoustic transducer is disposed within the hollow interior of the case, and the sealing diaphragm disposed over the top of the open end of the case such that the hollow interior of the case is completely sealed. An acoustic signal first impinges upon the sealing diaphragm causing deflections therein which in turn recreate the acoustic signal undiminished in the air space within the case between the sealing diaphragm and the active diaphragm.

Abstract: A truck of the cab-over-engine type is disclosed herein and includes a cab mounted over the truck engine and many of the engine's cooperating components for pivotal movement between an upstanding, operating position and a titled, maintenance position. The truck also includes a frontal nose hood mounted to and in front of the cab for its own pivotal movement between a closed, generally vertical operating position and a tilted, open position for gaining access to certain ones of the components cooperating with the engine. A front bumper assembly is provided in front of the nose hood and includes a first bumper arrangement connected for pivotal movement with and forming part of the frontal nose hood and a second bumper arrangement maintained in a fixed position and unconnected with the first bumper arrangement, whereby when the frontal nose hood and first bumper arrangement are pivoted to an open position, the second bumper arrangement remains in a fixed position.