Abstract: The electrodes of an electrostatic capacitor which is used to determine the alcohol concentration in a mixture of gasoline and alcohol, are connected with a frequency oscillator of the LC type which applies a signal having a frequency which is equal to or greater than 10 MHz. The setting of the oscillation frequency to 10 MHz or more eliminates the amount of change in electrode loss and enables stable and accurate alcohol concentration determination.

Abstract: A circuit for detecting and processing a signal from a sensing device such as a torque sensor is disclosed in which a first peak hold circuit detects a first peak value of an output AC signal of an oscillator and a second peak hold circuit detects the peak value of an output signal of a differential amplifier. The differential amplifier is connected across an output end of a bridge circuit for detecting a change in the output voltage from the torque sensor. A sign of a variable in the torque sensor is determined according to the first and second hold values derived from the first and second hold circuits. The magnitude of the variable of the torque sensor is detected according to the magnitude of the second peak value of the second hold circuit.

Abstract: A detection and processing circuitry of a magnetostriction type torque sensor is disclosed. An alternating current voltage signal Vo is generated and output from an oscillator. A shift circuit shifts a phase of the AC voltage waveform of the oscillator by 1/4 period and outputs the phase shifted voltage to a detector. The detector modulates the inverted voltage signal Va on the basis of the phase shifted voltage signal and an integrator integrates the detector output voltage in a time range from (.alpha.-.pi./2) to (.alpha.-3.pi./2). Thus, the output voltage signal Vd from the integrator indicates a resistance value of an imaginary part, i.e., inductance of the impedance of the detection coil of a magnetostrictive shaft of the torque sensor which is not dependent on the change in a temperature.

Abstract: An apparatus for testing an alcohol concentration sensor used in measuring an alcohol concentration of a fluid containing alcohol. The alcohol concentration sensor includes a capacitive probe having a capacity dependent upon the alcohol concentration of the fluid, and a circuit sensitive to the capacity of the capacitive probe for producing an output signal indicative of a sensed alcohol concentration. The apparatus comprises a plurality of capacitors having different capacities each corresponding to a predetermined alcohol concentration. A selected one of the capacitors is connected in parallel with the capacitive probe. When the selected capacitor is connected with the capacitive probe, the output signal is read.

Abstract: A system for sensing the nature of gasoline is disclosed, which comprises a capacitance type sensor for producing a first information signal representative of the dielectric constant of the gasoline; a temperature sensor for producing a second information signal representative of the temperature of the gasoline; a temperature coefficient deriving device for deriving a temperature coefficient of the gasoline from the first and second information signals; an additive concentration deriving device for deriving the concentration of alcohols in the gasoline from the temperature coefficient; a correcting device for correcting the first information signal in view of a reference temperature; and a judging device for judging the nature of the gasoline from the derived concentration of the additive and the corrected first information signal.