An Alternative Approach to Automotive Fuel Gauging

The need for accurate, high-resolution automobile fuel gauges is becoming increasingly felt and this can best be fulfilled with modern developments of the capacitance-measuring technique used for aircraft fuel tanks.

An inexpensive probe is described which can be used, with suitable circuitry, to give a 0.1 gallon resolution and accuracy, from which the influence of slosh and tilt is effectively eliminated.

A low-cost measuring circuit is described, based on CMOS astable oscillators, which produces digital readings virtually immune to noise, voltage and temperature changes, and the effects of ageing.