Abstract: According to some embodiments of the present invention, a system for detecting counterfeit or altered coins or bullion includes a sensor system, an alternating current (AC) power supply electrically connected to the sensor system, a detection system electrically connected to the sensor system and the AC power supply, and a data processor configured to communicate with the detection system. The sensor system comprises an impedance component and a measurement circuit. The detection system is configured to determine a calibration complex impedance and a sample complex impedance. The data processor is configured to receive the calibration complex impedance and the sample complex impedance from the detection system, and provide information regarding a composition of the sample to distinguish valid coins and bullion from at least one of counterfeit or altered coins and bullion.

Abstract: According to some embodiments of the present invention, a system for detecting counterfeit or altered coins or bullion includes a sensor system, an alternating current (AC) power supply electrically connected to the sensor system, a detection system electrically connected to the sensor system and the AC power supply, and a data processor configured to communicate with the detection system. The sensor system comprises an impedance component and a measurement circuit. The detection system is configured to determine a calibration complex impedance and a sample complex impedance. The data processor is configured to receive the calibration complex impedance and the sample complex impedance from the detection system, and provide information regarding a composition of the sample to distinguish valid coins and bullion from at least one of counterfeit or altered coins and bullion.

Abstract: A system for operating a plurality of motors with a single controller is disclosed. This system includes a first motor, a second motor that is matched to the first motor but has a lower power rating than the first motor and a controller electrically driving the first and second motors with a modulated voltage at one frequency selected from one or more frequencies over a complete range of frequencies. The controller generates a frequency of the modulated voltage from the range of frequencies which is proportional to the desired speed for the first and second motors. A method for building such a system is also disclosed. This system and method have particular application to HVAC systems.