Abstract: A fuel gaging system of the type wherein the capacitance of a probe (20) within the fuel tank is used as an indication of fuel quantity via an assumed density/dielectric constant relationship (10) of the fuel. System accuracy is improved by directly measuring fuel density and dielectric constant. These values are compared with the assumed values in a processor (68) which generates an appropriate gaging correction signal in response to a discrepancy.

Abstract: An overload protected switching regulator for applying power to a load is disclosed. A power switch (PS1, PS2), connected to control the flow of current between the DC input and the output of the regulator, is closed at a fixed rate each time a flip-flop (23, 33) is set by a pulse produced by an oscillator (21, 31). When the regulator is operated at its rated current, or less, an output voltage detector (25, 37) applies a pulse to the reset input of the flip-flop (23, 33) during each period of oscillation. The timing of the reset pulse is such that the open/closed ratio of the power switch (PS1, PS2) is the exact ratio required to maintain the output voltage of the regulator at the desired level. A current limit detector (27, 39) detects current flow through the power switch.

Abstract: The transient limiter suppresses high voltage transients induced on an alternating current (AC) carrying power line. A Zener diode string breaks down for voltages on the line which exceed the peak AC voltage. The breakdown current is directly connected to the gate terminals of a pair of silicon controlled rectifiers (SCR's). Each rectifier is series connected to a voltage responsive resistor with the combination being connected across the power line terminals. Upon breakdown of the Zener diode string one of the SCR's and its associated voltage responsive resistor switch to a low impedance state, thereby limiting the peak voltage on the power line.

Abstract: High voltage transients, such as from lightning strikes, on an AC carrying power line are suppressed by unique protection circuitry. Voltage on the line is sensed and should it exceed a predetermined reference level an appropriate one of two silicon controlled rectifiers is activated. The rectifiers are connected in series with a voltage dependant resistor and the resultant network is coupled between the terminals of the power line. The network is effectively an open circuit under exposure to the periodic waveform normally existing on the power line. Upon occurrence of a high voltage transient, the combination of one of the rectifiers and the voltage dependant resistor switches to a low impedance state, thereby accomplishing suppression.

Abstract: The signal generator produces an output comprised of a periodic signal and a precision amplitude pulse. A periodic waveform source is fed to the center tap of a transformer. The instantaneous amplitude of the waveform is sensed and, when it reaches a predetermined level, one free end of the transformer is grounded thereby producing a predetermined amplitude pulse, superimposed on the periodic waveform, at the remaining free end.