Abstract: Digital circuitry for use primarly in measuring the volume of gasoline in an automobile fuel tank. A measurement capacitor is mounted in the fuel tank to have its capacitance vary with the level of gasoline in the tank and forms part of a multivibrator circuit the repetition rate of which is consequently varied in an inverse manner with the capacitance of the measurement capacitor. Pulses generated in the multivibrator are fed to a counter coupled to a resetting circuit which is triggered by an output of this counter when a predetermined number of the said pulses has been counted so that a train of resetting signals are generated separated by intervals the length of which is a measure of the capacitance of the measurement capacitor.