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 seed flow detector for use with a seed tube, comprised of a pin for extending radially into the seed tube, the end of the pin being orthogonally fixed to one face of a piezoelectric crystal transducer. Flexible resilient material is disposed against the other face of the transducer so as to damp mechanical vibrations below a predetermined frequency. Substantially no build-up of seeds or blockage of the seed tube results, mechanical vibration is substantially damped, while signals resulting from the impact of seeds against the pin are reliably generated.

Abstract: An element used in determining the conductivity of fluids. An insulating tube is provided for carrying the fluid to be measured. Cylindrical electrodes surround the tube at laterally spaced positions. When a signal is applied to the electrodes, the tube and fluid act as dielectric in a capacitor. Measurement of the amount of current passed by the capacitor provides an indication of the conductivity of the fluid. Means is provided to minimize the effect of stray currents.

Abstract: A fluid conductivity measurement apparatus in which the minimum conductivity of one fluid of a group of fluids is determined by comparing electrical conductivities, and the ratios of each of the conductivities to the minimum conductivity are calculated. Where cow's milk is the fluid passing through the apparatus, a determined deviant increase in ratio has been found to be evidence of a high probability of bovine mastitis.