Abstract: A vehicle guidance system is disclosed that is suitable for guiding a vehicle or person along a straight line navigational aspect with signaling and processing typical of hyperbolic navigational systems, for example, in certain farming operations where the farm vehicle utilized must repeatedly be caused to traverse an unmarked field in substantially straight parallel paths that are evenly spaced with respect to one another, such as in fertilizing the field. An electronic navigation system is utilized which includes a transmitter and a receiver positioned upon the navigating vehicle and a pair of repeating transmitter/receivers spaced with respect to one another a known or measured distance and along a line normal to the intended straight line path to be followed by the vehicle. The transmitter causes each repeater to be alternately energized and the resulting signal is detected at the vehicle mounted receiver and the phase difference between each transmitted and received signal is measured.

Abstract: A solid state electronic alarm circuit including means for sensing a predetermined change in a parameter such as the temperature in a freezer or the like from a predetermined safe limit and means for generating an audible alarm in response thereto.

Abstract: Disclosed is an energy conserving thermostatic control for use wih heating and/or air conditioning systems. The control includes solid state circuitry for automatically controlling or regulating the temperature of an area at at least two different selected temperatures at selected times and for selected periods. The control is compatible with conventional heating and/or air conditioning systems and in most instances can be installed therewith without modification or rewiring of the system.