Abstract: A method and apparatus for detecting completion of the dissolution of a soluble solid material in a liquid in a container. The container and its contents are excitated by a wide frequency band excitation signal, causing the container and its contents to respond at a predominant frequency. The frequency response of the container and its contents is successively sampled and measured, and the respective predominant frequency response values are compared with preceding values. As the solid dissolves in the liquid, the predominant response frequency will change. Once the predominant frequency response stabilizes from sample to sample at a particular value, the dissolving process is complete. The detection method and apparatus can be used to control a motorized agitator to prevent overmixing and save energy.

Abstract: Electrical connection apparatus is disclosed for achieving versatile connections between bus boards and electrical devices having conductive pins which extend through holes in the boards. Connections are achieved through transversely expansible conductive washers within the holes around the pins. Transverse expansion is caused by compression of individual washers along central axes of the holes, the compression being produced by expander means associated with the washers. Two expansible washer configurations are disclosed, one comprising spring material preformed with protuberances which are flattened to cause transverse expansion, and the other comprising a conductive elastomeric material.