Abstract: An oscillator which produces a continuous wave output signal on an antenna having a preset frequency. A detection circuit detects changes in the preset frequency resulting from proximity between the antenna and an object and when such an object is detected, the detection circuit generates an output signal. A compensation circuit is also provided for compensating for changes of the preset frequency which are caused by factors other than proximity of the antenna with an object. Such other factors include radio frequency interference, long term component degradation, temperature, and the like.

Abstract: An electromechanical locking device completely contained within a doorknob which can be a part of a usual lockset or retrofitted on an existing lockset which requires entry of an access code or entry of both an access code and use of a mechanical key for operating the lock. The code is entered on a keypad exposed on the knob and supplies a signal to a computer powered by batteries. A correct match of the input code to a code stored in the computer will actuate a motor operated cam to release a mechanical interlocking pin enabling the lock cylinder to be rotated to the unlocked position. Both visual and audible signals may be provided in the doorknob as to the power level of the batteries and ready condition of the lock. The mechanical interlock pin is disengaged automatically from the lock cylinder upon the power level of the batteries dropping to a predetermined level requiring only mechanical key operation of the lock.

Abstract: An electronic ON/OFF control system for use on a powered hand tool to ensure operator safety and ease of operation. The hand tool is driven either by an electric motor driven, flexible drive shaft or a source of pressurized air supplied to the hand tool through a supply line. A low power frequency is applied alternately to the hand tool and power supply line. Appropriate circuitry detects changes in the frequency of the applied signal caused by an operator grasping the hand tool and power supply line and the sequence in which the two components are grasped. If the hand tool is being grasped when the drive shaft or supply line is subsequently grasped a signal is supplied to a power control unit which actuates the power source for the hand tool. The power control unit maintains the hand tool energized after releasing of the operator's grasp on the on the power supply line and automatically de-energizes the hand tool upon the operator releasing his grasp on the hand tool.