Abstract: A water pump pressure switch that is adapted to provide a system for automatic power shut-off to the well pump. The water pump pressure switch is specifically adapted to provide such feature by incorporation of additional components such as an electromechanical solenoid that upon receipt of a signal engages with a lift bar which opens electrical contacts, disrupts power feed to the well pump, sounds an audio alarm or sends a signal to a house alarm or a wireless device.

Abstract: An electronic sensing circuit, which can be used in place of a linear variable differential transformer (LVDT) has four piezoresistor elements in a Wheatstone bridge configuration. A source voltage is applied across a first pair of bridge points, and the resulting junction voltages appearing at a second pair of bridge points are applied to a pair of inverting amplifiers in balanced configuration which provide first and second output voltages which change relative to each other depending upon the direction and amount of pressure applied to the piezoresistor elements in a manner similar to the output voltages provided by an LVDT.

Abstract: A circuit for linearizing the output of a differential pressure transducer includes first and second operational amplifiers. Each amplifier is associated with threshold devices as diodes so that one amplifier will be active for one condition of output polarity while the other amplifier will be active for the other condition of output polarity. The output of the amplifiers are connected to a common terminal which provides a compensating biasing voltage to the transducer. The voltage varies in a "V" shaped characteristic to enable one to achieve a linear output voltage from the transducer for both positive and negative pressure differences.