Abstract: An input waveform follow-up AC power source system is shown, which can obtain a desired sinusoidal voltage or current wave continuously and with the same or a similar waveform from a constant power source, as well as being small in size and light in weight.The AC power source system, which provides a desired AC voltage or current from an AC power source, comprises a first AC switch provided between the input side and the output side and on-off operated in a predetermined cycle, and a second AC switch provided on the output side of the first AC switch and at a position to short-circuit the output side and on-off operated conversely to the first AC switch. A predetermined pause time is provided between the operations of the first and second AC switches.

Abstract: A container lid has a depending insert having a thickness sufficient to have a groove formed in its peripheral edge, and a beverage container has an annular, radially inwardly extending protrusion formed in it that snaps into the groove when the insert is inserted into the container. The connection is so strong that the lid will not separate from the container even when the cup is filled with a beverage or food and inverted. The lid includes a peripherally positioned handle that enables facile removal of the lid, and the interconnection between the lid and the container includes a double seal that inhibits the risk of spillage.