Abstract: A liquid heating vessel, such as a kettle, enables user selection of the temperature to which the liquid is to be heated. A thermal sensor is provided which is responsive to the temperature of the heating element. During the heating cycle, the operation of the heating element is interrupted, and temperature samples are obtained as the element cools. Analysis of the temperature decay function of the heating element during the interruption enables the liquid volume to be estimated, as well as the time required to heat the liquid to the selected temperature.

Abstract: An appliance provided with an electric motor and a circuit for driving the electric motor. The drive circuit includes a first pulse switch (S1) for generating a first pulse and a first switching device (.mu.C, T) having a holding capability and which performs a first switching function in response to the first pulse. A second pulse switch (S2) generates a second pulse. A second switching device (Th, R) having a holding capability performs a second switching function in response to the second pulse. A main switching device switches the electric motor. The first switching function in combination with the second switching fucntion are adapted to control the main switching device. Optionally, the circuit may include a control device (Tr) for controlling the electric motor and a third pulse switch (S3) for resetting the first switching function.

Abstract: An irradiation device including a series arrangement of an ultraviolet radiation source (5), a first switch (3) and a second switch (4). Under normal conditions the radiation source (5) is switched on and off by the first switch (3). The second switch (4) is operative only if the first switch (3) fails. By means of a simple circuit (7, 20, 17, 6; R), the defective device cannot be switched on again.