Abstract: A low-loss sinusoidal drive system is disclosed for powering thin-film electroluminescent displays (TFEL). A DC power source coupled through a DC-to-AC inverter and driving an LC resonant tank circuit is used to produce a sinusoidal supply voltage. The sinusoidal supply voltage is coupled to produce a sinusoidal backplane driving voltage and coupled to a synchronizer circuit which controls drive logic for selectively energizing segments of the TFEL display. The drive logic is coupled to respond to an on-off command for selecting a particular segment such that the average DC voltage across a segment of the TFEL is zero, independent of the on/off condition of the segment. The backplane sinusoidal voltage may be applied in common to multiple TFEL devices with the synchronizing and drive logic circuits individually selecting the segments for TFEL drive.

Abstract: A power supply for a low-loss sinusoidal drive system is disclosed for powering thin-film electroluminescent displays (TFEL). A DC power source is coupled through a DC-to-AC inverter for driving an LC resonant tank circuit which is used to produce a sinusoidal supply voltage. A sinusoidal supply voltage is then coupled to produce a sinusoidal backplane driving voltage which, in cooperation with a logic circuit, controls the drive for selectively energizing segments of the TFEL display. The power supply is constructed to synchronize itself with the tank circuit in such a manner that sufficient power is added to make up for the tank losses and allow the tank to ring with a sustained constant voltage level. This produces an efficient sinusoidal power source which can accommodate varying loads and is operable at low voltage levels independent of output voltage requirements.

Abstract: A measuring system includes a plurality of resistors and circuitry connected thereto which generates first and second signals each containing different information about one or more of the resistors. Each information is possibly contaminated by error but only by substantially the same error contaminating the other information. Subtraction of two such informations thus gives error-free information because the like errors cancel.

Abstract: A measuring system includes a plurality of resistors and circuitry connected thereto which generates first and second signals each containing different information about one or more of the resistors. Each information is possibly contaminated by error but only by substantially the same error contaminating the other information. Subtraction of two such informations thus gives error-free information because the like errors cancel.

Abstract: Strain gauge apparatus comprises two strain sensitive piezoresistors R.sub.r1 and R.sub.t1, two op-amps, three predetermined value resistances, R.sub.a, R.sub.b, and R.sub.c, and voltage source supplying V.sub.dc. Said elements are connected to produce an output signal of the form V.sub.dc (R.sub.c /R.sub.a l ) (R.sub.r1 / R.sub.t1 -R.sub.a /R.sub.b).

Abstract: Strain gauge characteristic stabilization apparatus comprises a parallel connected combination of strain sensitive resistance (i.e., R.sub.eq), temperature conditioning means proximate R.sub.eq, and circuit means between R.sub.eq and the temperature conditioning means. The circuit means senses deviations in R.sub.eq from a predetermined value and causes the temperature conditioning means to control the temperature of R.sub.eq so as to reduce the deviations substantially to zero.