Abstract: Apparatus, methods and systems for controlling a dust collecting system are presented. A system includes a plurality of sensors paired to a corresponding plurality of blast gates, and a controller coupled to receive a signal from each of the plurality of blast gates. The sensor non-invasively detects power flow through a tool's power cord. The controller is coupled between a collector and the blast gates. The blast gates may be configured in a star and/or daisy-chained configuration allowing for flexible installation. The controller instructs the collector to turn on and off based on a sensor signal received via a corresponding blast gate.

Abstract: A method and apparatus to detect non-cancelled magnetic field produced when current flows through an electric conductor are provided. The sensor includes multiple coils, which allow the sensor to be arbitrarily oriented and attach to the outside of an electrical power cable. Arbitrary orientation provides for easy of field installation.

Abstract: A wireless (e.g., radio) system and method for automatic water level maintenance of, e.g., a swimming pool utilizing capacitive liquid level sensing. A reference electrode allows water level sensing independent of the water chemistry or temperature. Capacitive electrodes having areas larger than the reference electrode sense various liquid levels when the liquid covers an area of any sensing electrode equal to the area of the reference electrode. Averaging is incorporated to filter out effects of wind or other disturbances. Upon sensing a given condition, the transmitter transmits a sensed condition to a remote receiver for control of valves and pumps for changing the water level in the pool. The receiver includes safety timers for filling and emptying to protect against equipment failure or communications faults. User selectable identification allows identical such radio systems to operate within proximity to each other. Power saving features are used to extend battery life.