Abstract: A coin detection apparatus is disclosed which is particularly suitable for low power applications. The coin detection apparatus utilizes a detector coil as part of a resonant circuit. The resonant circuit with no coin present in the detector coil has a damped impulse response. When a coin is present within the detector coil, the damping of the impulse response of the resonant circuit is increased. Periodic generation of an impulse input to the resonant circuit and measurement of the resulting impulse response enables the presence of a coin within the detector coil to be ascertained.

Abstract: An apparatus for sensing coins is disclosed which is capable of distinguishing between valid and non-valid coins as well as between the different denominations of coins. The apparatus is useful for application in coin-operated parking meters as well as other coin-operated machines. The apparatus makes use of a twin-coil sensor which enables it to distinguish between small coins with high metal content and large coins with low metal content.

Abstract: A low-power receiver for extracting a digital data signal from a modulated carrier signal is disclosed. The receiver employs an amplifier whose stages share the same bias current in order to reduce power consumption.