Abstract: A sensing device having a sensing surface for placing against a wall for detecting objects behind a wall lining has first and second sensors, each sensor including at least first and second capacitor plates and associated resistors forming RC circuits having time constants dependent on the adjacent wall material. Detection circuits connected to the RC circuits provide first and second voltage signals having amplitudes dependent on capacitance changes. A processor effects a comparison of the first and second voltage signals, and compares them to establish the magnitude of the voltage difference between the voltage signals, indicating a detected object center position when the difference signal is less than a predetermined value.

Abstract: A multiple sensitivity stud sensing device for determining a location of objects behind a wall lining has a housing with a surface for moving over the wall lining. Within the housing are a capacitive sensor with first and second capacitances located adjacent the surface and control circuitry. The control circuitry includes a detecting circuit connected to the sensor for providing a detection signal related to an imbalance between the first and second capacitances, and a processor for receiving the detection signals and providing a display signal. A display is located on the housing for indicating location of an object behind the wall lining. The processor compares a detection signal to stored predetermined threshold values of detection signals associated with different wall lining thicknesses and displays a thickness value to the user.

Abstract: A sensing device having a sensing surface for placing against a wall for detecting objects behind a wall lining has first and second sensors, each sensor including at least first and second capacitor plates and associated resistors forming RC circuits having time constants dependent on the adjacent wall material. Detection circuits connected to the RC circuits provide first and second voltage signals having amplitudes dependent on capacitance changes. A processor effects a comparison of the first and second voltage signals, and compares them to establish the magnitude of the voltage difference between the voltage signals, indicating a detected object center position when the difference signal is less than a predetermined value.