Abstract: In electronic measuring systems the accuracy of measurement is affected by drift not only of the zero but of the gain due to temperature changes, aging and supply conditions. The invention provides an automatic gain correction means so as to maintain an accurate relationship between the magnitude of the characteristic being measured and the value displayed or recorded. The measuring system is such that a train of pulses is counted over a predetermined time interval with a train of pulses representing, by its pulse repetition rate, the magnitude of the characteristic. A reference count is provided and means are provided for generating a pulse train simulating a predetermined magnitude of the characteristic being measured. Means are provided for counting the pulses of the generated pulse train and means are provided for comparing the reference count with the count of the generated pulse train to determine any error in the gain.

Abstract: A vertical float switch, suitable for use as a low water cut-off control or the like, having differential adjustment means is disclosed. The float switch includes a hollow housing forming a float chamber which communicates with a hot water boiler vessel by way of vertically spaced equalizing lines. A non-magnetic sealing tube extends vertically away from the housing and communicates with the float chamber of the housing. A float rod is slidably mounted within the housing by way of a generally cylindrical guiding collar. A float is mounted to the lower end of the rod for translating the rod in accordance with the level of the water within the float chamber. An armature of magnetic material is fixedly mounted to the other end of the rod for translation with the tube in accordance with the level of the water within the boiler. A switch frame is clamped at a predetermined point along the tube, and includes a bracket pivotally mounted thereon for translation toward and away from the tube.

Abstract: A weighing system is described in which a weighing platform is operatively coupled to a transducer arrangement included in an electrical bridge circuit having connected therein a tare resistor arrangement for balancing out the tare weight of the platform. Means are provided for selectively isolating the effect of the tare resistor arrangement from the bridge circuit so that the system output indicates the sum of the tare weight of the platform and the weight of any load on the platform, thereby enabling the weighing system to be checked using the weight of the platform.