Abstract: A device providing reverse polarization protection for a battery having both positive and negative terminals disposed at one end of the battery (e.g., a 9 volt “transistor radio” battery). The device is adapted for insertion between the battery terminals and the spring contacts in a battery housing. The device is made from an electrically insulating material (e.g., plastic), and has at least two openings of unequal size defined through it. The first opening has a diameter larger than that of a negative terminal of the battery, while the second opening has a diameter larger than that of a positive terminal of the battery. The second opening is sized such that the negative terminal of the battery cannot pass through it, thus providing the required mechanical interference for reverse polarity protection. The thickness of the device is less than the height of the battery terminals.

Abstract: A display in a portable detector unit (e.g., a handheld “stud sensor”) projects a pattern of light onto a surface beneath which a hidden object is located. The pattern represents the location of a sensed characteristic of the object with respect to the surface. The pattern may include a single line or a plurality of lines, and may be projected in one or more directions.

Abstract: An improved hand-held sensor having a recessed LED array for indicating the location of an object behind a wall surface. The array displays in an arrow shaped format the location of the sensor relative to the object. The LED's can be offset both laterally and in depth from the surface of the sensor exterior case and are recessed from the surface. The sensor includes a soft feeling slip-resistant gripping surface for the user. One form of the sensor includes a slide switch actuator, which is retained in one wall of the sensor case to enable actuation of a switch mechanism without physical loading on the switch mechanism.

Abstract: A device for locating the edges of wall studs includes a comparison circuit connected to each of three capacitive elements. As the device is moved along a wall, the comparison circuit monitors the relative charge time associated with each capacitive element, the charge times providing an indication of the relative capacitances of the three capacitive elements. Changes in the relative capacitances of the three elements as the device is moved along a wall are due to a change in the dielectric constant of the wall, which normally results from the presence of a wall stud behind the surface over which the device is moved. The comparison circuit uses differences in the measured relative capacitances of the first, second, and third capacitive elements to locate the edges of the stud.

Abstract: An ultrasonic distance measuring device for use, for instance, in the building trades, conventionally measures distance by projecting a sonic beam towards the target and detecting the reflection from the target. Also provided is an associated co-axial laser pointer which provides a visual indication of where the sonic beam is pointed. This laser pointer provides a laser beam which illuminates the target. However, the laser beam is not a typical laser beam, but instead is diffracted so that it covers an area at the target approximately the same size and shape as the area covered by the sonic beam. This provides a clear indication to the user that the sonic beam is not a single point beam but instead is possibly reflecting from any one of a number of points on the target.

Abstract: An impulse radar system useful, for instance, for ground penetration provides three dimensional images of targets. The radar system includes an antenna array with an arrangement of elements that is irregular so that the spacing between elements is different, thereby minimizing redundancy of path geometry between the array elements and the target. This feature reduces unwanted array sidelobes. The radar system incorporates circuitry which permits the utilization of each array element as either a transmitter or receiver antenna element. This dual utilization increases the effective number of elements in the antenna array, providing increased gain and system resolution. The radar system receiver utilizes multiple antenna array receiver elements, each of which is connected sequentially, through a solid state switch, to a single analog to digital converter, thereby providing a digitized signal for processing and display.

Abstract: An electronic level with a laser inclination indicator. In one embodiment, the level includes a sensor that determines an inclination of the device relative to a null inclination. The sensor generates an inclination indication signal. A housing in which the sensor is mounted defines a longitudinal axis. A laser mounted on the housing generates a light beam parallel to the longitudinal axis. A laser controller receives the inclination indication signal from the sensor and selectively provides power to the laser in response to the inclination indication signal. In one embodiment, the level also includes a visual display on the housing operatively connected to the sensor and displaying the determined inclination. The visual display has a plurality of illuminated non-parallel and adjacent segments, each segment representing a predetermined sequential increment of inclination. Each segment is arranged at a different angle relative to the longitudinal axis of the housing.

Abstract: A dual sensitivity stud sensor senses studs through both thick and thin surfaces. Studs are sensed by detecting a change in the capacitive loading of plates as they are moved along a surface and into proximity with a stud. The sensor informs the operator when the sensor has (incorrectly) been calibrated over a stud. The sensor also informs the operator if the sensor is placed against a surface either too thick or too thin for stud detection. Through use of a digital register, the sensor remains calibrated indefinitely while the sensor is powered on.

Abstract: An improved laser adjustment mechanism providing precision alignment of the laser in two dimensions. The mechanism includes a pair of biased threaded mechanisms orthogonally captured by a laser module, which are adjustable to pivot the laser in a plane substantially even with the plane of the laser light emission. The threaded mechanisms are adjustable from the exterior of the level and can precisely align the laser device by placing the device on a surface. A first laser spot is measured at a distant plane, then the device is turned over on the same surface and a second target spot is measured on the same plane. The laser is adjusted half way between the two target spots to precisely align the pitch of the device. The device then can be turned on the side to align the yaw of the device.