Abstract: A sensor system for sensing liquid level in a bilge, for use in automatic bilge pump actuation. First and second field effect sensors are potted or sealed within a container or the bilge wall and are aligned in a vertical array and each comprise a substantially planar pattern of “electrodes” or conductive traces disposed on a printed circuit board (PCB) along with integrated circuits used to create a loop or arc-shaped electric field. As bilge liquid rises to the proximity or level of the field effect sensors, a change in the arc-shaped electric field is sensed and, in response, a bilge pump is automatically actuated to pump liquid out of the bilge. Optionally, the pump control can be programmed by use of a microprocessor to permit control of on-off timing and is prevent undesirable effects of “sloshing.

Abstract: An EMI resistant, low impedance touch sensor detects contact of a dielectric substrate by an operator's appendage or body part, a metal object, or the proximity of a moving fluid/gas interface. The touch sensor includes a first conductive electrode pad and a second conductive electrode of substantially equal area which is spaced from the first electrode by a channel of non-conductive dielectric. The first and second electrodes are optionally disposed on the same surface of the substrate. An active electrical component including an oscillator and a differential sensing circuit is located on the substrate proximate the first and second electrodes and is electrically coupled to the first and second electrodes. Noise or interference signals appearing on both the first and second electrodes, being of substantially equal area, are subtracted from one another through to provide common mode rejection of EMI.

Abstract: A sensor system for sensing liquid level in a bilge, for use in automatic bilge pump actuation. First and second field effect sensors are potted or sealed within a container or the bilge wall and are aligned in a vertical array and each comprise a substantially planar pattern of “electrodes” or conductive traces disposed on a printed circuit board (PCB) along with integrated circuits used to create a loop or arc-shaped electric field. As bilge liquid rises to the proximity or level of the field effect sensors, a change in the arc-shaped electric field is sensed and, in response, a bilge pump is automatically actuated to pump liquid out of the bilge. Optionally, the pump control can be programmed by use of a microprocessor to permit control of on-off timing and prevent undesirable effects of “sloshing.