Abstract: An improved gas density transducer which compares the resonant frequency of an enclosed, reference tuning fork crystal oscillator with the resonant frequency of a detector tuning fork crystal oscillator exposed to the surrounding gas. The frequency of oscillation of the detector crystal oscillator exposed will vary in accordance with the gas density because of the motional resistance of the gas to vibrations of the tuning fork oscillator. The frequency of the detector oscillator can be compared to the frequency of the reference oscillator to determine the gas density.

Abstract: A combination speedometer/odometer apparatus for displaying either the speed of a vehicle or the distance a vehicle has traveled, and including a speed pick-up attached to the vehicle for developing a first voltage signal having voltage spikes occurring at a frequency proportional to the speed of the vehicle; a pulse generator which develops a voltage pulse in response to each spike, the pulses having a predetermined duration; a signal generator controlled by the voltage pulses which develops a speed signal and a distance signal both having bursts of high-frequency signal, the number of bursts in the speed signal being proportional to the speed of the vehicle and the number of bursts in the distance signal being proportional to the total distance the vehicle has traveled; a first counter for counting the cycles of the speed signal, the counter initiating its count in response to a reset signal; a synchronizer for developing the reset signal a predetermined period of time after the occurrence of one of the vol