Abstract: A seed flow monitor for use with a plurality of seed flow sensors which are located in individual tubes of a field seeder. In the event of detection of reduction of seed flow in any seed tube below a predetermined threshold, a pulse signal is sent to a central display via circuits, associated with each group of seed flow sensors, connected in series. Each of the circuits modifies the pulse signal in a predetermined similar manner, resulting in a pulse signal received at the central display which is unique to the group of seed tubes originating the pulse signal. Preferably the pulse signal is constantly transmitted to the circuits by the central display, and is merely coupled into the series of circuits upon detection of the seed flow below the threshold. The cabling complexity from the sensors to the control display is thus substantially reduced and reliability is enhanced.

Abstract: A flowmeter for measuring the flow rate of fluids, having a range from a very low to a very high value. An impeller is located in a pipe for rotation with the flow of fluid. Metallic vanes of the impeller pass through the field of an inductor which is in a series circuit with a capacitor. An oscillator applies a signal at the series resonant frequency of the capacitor and inductor. The envelope of the resulting high voltage signal across the inductor is detected, filtered, and the resulting output pulses in excess of a minimum threshold can be applied to a counting apparatus for establishing the flow rate with high sensitivity. Since the spacing between the impeller and pickup is not critical, a meter is provided which does not clog with magnetic or non magnetic particles suspended in the fluid to be measured. The meter pickup can also be used to sense the rotation rate of wheels or the like having metallic discontinuities, whereby the speed of a vehicle, the rotation rate of a shaft, etc. can be determined.