Abstract: A method for determining a moment in a preparation process of food at which the food. has reached a ready state, the method comprising the following steps:—determining a initial water content, of the food;—determining a final water content of the food, which is associated with the ready state of the food;—determining an actual quantity of the food;—determining a. required quantity of released water, i.e.

Abstract: The invention relates to an electrical surface treatment device which is provided with an acoustic surface type detector with which a type of a surface to be treated can be detected during operation. According to the invention, the surface type detector delivers an output signal (u.sub.FT) during operation which is characteristic of the type of surface to be treated and which is determined by a value of a physical quantity of air vibrations reflected by the surface to be treated, which value is measured by a vibration detector of the surface type detector. In a special embodiment, the physical quantity is an amplitude, and the surface type detector is a vibration generator for generating air vibrations having a predetermined amplitude. The generated air vibrations preferably have a frequency of at least 15,000 Hz which varies within a predetermined range.

Abstract: A power-supply and communication circuit is based on a flyback converter with a transformer (6) whose primary winding (10) is periodically connected to a supply voltage by means of a switching element (8) in the rhythm of control pulses from an oscillator (24). Data communication to the secondary electronic circuitry (4) is effected by interrupting the control pulses in response to a first data signal (SDTA1) to be transmitted. The absence of the alternating voltage across the secondary winding (18) is detected by means of a peak detector (28) and converted into a received first data signal (RDTA1). Data communication to the primary electronic circuitry (2) is effected by actively modulating the rectified voltage at the secondary side by means of a modulator (30) in response to a second data signal (SDTA2) to be transmitted. The resulting fluctuations in the flyback voltage across the primary winding are detected by means of a second peak detector (32) and converted into a received second data signal (RDTA2).

Abstract: A shaving apparatus (1, 101, 201) is provided which includes at least one cutting unit (11) which is provided with an external cutting member (13) with at least one hair trap opening (17) and with an internal cutting member (19) which is rotatable in the external cutting member (13) by means of an electric motor (23). The speed of the motor (23) can be controlled during operation by a feedforward control unit (43, 103, 203) as a function of at least one physical quantity which can be measured during operation by means of a transducer (59, 69, 111).A first embodiment of the shaving apparatus (1) comprises a timer (59) which measures a time which has elapsed during a shaving operation, and a detector (69) with a microphone (71) which measures a cutting frequency of the cutting unit (11), the speed of the motor (23) being controllable by the control unit (43) as a function of the time which has elapsed during the shaving operation and of the cutting frequency.

Abstract: A vacuum cleaner is provided which has a motor housing (2) and a hose (8), which can be coupled via two mains-voltage wires (38, 42), one communication wire (48) and contacts (32, 34, 30). The motor housing (2) and the handle (10) of the hose (8) include microprocessors (6, 12) which communicate with one another via the communication wire (48). The first reference signal (26) of the one microprocessor (6) is connected to the one mains voltage terminal (18) and the second reference signal (44) of the other microprocessor (12) is connected to the other mains voltage terminal (40).