Abstract: A tap sensitive alarm clock has a housing (20), a vibration sensor (22) mechanically coupled to the housing for receiving a shock due to a user tapping the housing, and a control circuit (24) coupled to the vibration sensor for controlling a function of the alarm clock. An audio unit (26) is coupled to an audio circuit (25) for generating sound, e.g. a loudspeaker in an alarm clock or a wake up light. To avoid interference of the sound and the vibration sensor, the alarm clock is provided with a filter (23) coupled to the vibration sensor and the control circuit. The filter has a filter curve matched to block frequencies occurring in the sound. Advantageously it is avoided that the sound frequencies trigger the function, while the sensor is sensitive to other frequencies up to the frequency range of the sound for reliably detecting the tapping.

Abstract: A tap sensitive alarm clock has a housing (20), a vibration sensor (22) mechanically coupled to the housing for receiving a shock due to a user tapping the housing, and a control circuit (24) coupled to the vibration sensor for controlling a function of the alarm clock. An audio unit (26) is coupled to an audio circuit (25) for generating sound, e.g. a loudspeaker in an alarm clock or a wake up light. To avoid interference of the sound and the vibration sensor, the alarm clock is provided with a filter (23) coupled to the vibration sensor and the control circuit. The filter has a filter curve matched to block frequencies occurring in the sound. Advantageously it is avoided that the sound frequencies trigger the function, while the sensor is sensitive to other frequencies up to the frequency range of the sound for reliably detecting the tapping.

Abstract: A tap sensitive alarm clock has a housing (20), a vibration sensor (22) mechanically coupled to the housing for receiving a shock due to a user tapping the housing, and a control circuit (24) coupled to the vibration sensor for controlling a function of the alarm clock. An audio unit (26) is coupled to an audio circuit (25) for generating sound, e.g. a loudspeaker in an alarm clock or a wake up light. To avoid interference of the sound and the vibration sensor, the alarm clock is provided with a filter (23) coupled to the vibration sensor and the control circuit. The filter has a filter curve matched to block frequencies occurring in the sound. Advantageously it is avoided that the sound frequencies trigger the function, while the sensor is sensitive to other frequencies up to the frequency range of the sound for reliably detecting the tapping.

Abstract: A tap sensitive alarm clock has a housing (20), a vibration sensor (22) mechanically coupled to the housing for receiving a shock due to a user tapping the housing, and a control circuit (24) coupled to the vibration sensor for controlling a function of the alarm clock. An audio unit (26) is coupled to an audio circuit (25) for generating sound, e.g. a loudspeaker in an alarm clock or a wake up light. To avoid interference of the sound and the vibration sensor, the alarm clock is provided with a filter (23) coupled to the vibration sensor and the control circuit. The filter has a filter curve matched to block frequencies occurring in the sound. Advantageously it is avoided that the sound frequencies trigger the function, while the sensor is sensitive to other frequencies up to the frequency range of the sound for reliably detecting the tapping.

Abstract: A hydraulic operating system has a cylinder which is actuated to raise, hold or lower a load against the force of gravity. An electromagnetic 3/2 valve connects a working chamber of the cylinder to a hydraulic reservoir when not energized, and permits flow from a pump to the working chamber when energized. A non-return valve prevents flow from the working chamber to the pump when the valve is energized. A three position switch operates an electric control unit to raise, lower or hold the load in an intermediate position. When holding in an intermediate position, the control unit constantly energizes the valve during a first period, after which the control unit intermittently energizes and deenergizes the valve so as to lower the load in stepwise fashion during a second period.