Abstract: A liquid level measuring apparatus is provided, which includes an input circuit configured to receive electrical signals from level sensors configured to provide an electrical signal proportional to a liquid level in a tank portion. The input circuit provides a single output signal proportional to the combined liquid level in one or more liquid storage vessel portions. The apparatus may further include or be connected to a transmitter such as a wireless transmitting device.

Abstract: A touch sensor is provided which detects manual contact by a user to actuate a controlled device. The touch sensor includes a substrate, an RF signal transmitter including a plurality of first conductors, and an RF signal receiver including a plurality of second conductors. The first and second conductors are located in spaced, interdigitated alignment with one another on the substrate, to form a key having a geometry which affords substantial coverage thereof by a human appendage. The RF signal receiver includes an RF signal amplifier electrically coupled to the second conductors. A processor is electrically coupled to the RF signal receiver to detect variations in signal strength corresponding to coverage of the key by a human appendage to selectively actuate the controlled device.

Abstract: A hazard alarm and alarm system enables a plurality of hazard alarms of multiple types (e.g. smoke alarms, heat alarms, motion detectors, carbon monoxide alarms, gas alarms, and the like), to communicate with one another without generating conflicting alarm warning indicators. Electronic circuitry is also provided, that may be added to at least one of the hazard alarms, for transmitting and receiving digital information with other hazard alarms connected thereto.

Abstract: A capacitance measurement circuit and probe includes a drive circuit couplable to a constant-current source, a threshold detector, a probe capacitor, and a reference capacitor. The circuit includes a plurality of switches being actuatable to alternately couple the current source to the probe capacitor and to the reference capacitor. The drive circuit is configured to alternately generate a signal of linear ramp waveform having a slope that is proportional to the magnitude of capacitance of the probe capacitor and of the reference capacitor. The voltage differential between the probe capacitor and reference capacitor are actively nulled to nominally eliminate a parasitic capacitance therebetween.