Abstract: A system and method for reducing the amount of electrical noise in a signal produced by a temperature sensor for an appliance which utilizes a running average calculation to provide a more accurate sensor reading in an inexpensive and efficient manner. Consecutive readings obtained by the sensor are digitized and stored in a circular buffer. A running average of the readings stored in the buffer is made upon each new reading and the concurrent erasure of the oldest reading.

Abstract: A coin acceptor mechanism (10) for recognizing the valid input of a coin (18) into a coin operated device wherein the mechanism (10) includes a sensor (28) which produces an electrical signal (30) indicative of the sensed presence or absence of a coin. A microprocessor (14) generates a periodic pulsed signal (46) and during a predetermined time period counts the number of pulses generated while the sensor output signal (30) indicates that a coin is present. Upon expiration of the predetermined time period, and once the sensor output signal (30) indicates the absence of a coin, pulses generated thereafter are counted. Once this count exceeds a predetermined value, a valid input is indicated if the first count also exceeded a predefined number.

Abstract: An appliance temperature sensor for acquisition of usable data in a noisy environment collects a plurality of temperature readings in a buffer. It then screens that batch of data to determine whether or not its noise content is acceptably low before forwarding the data to a memory for use in subsequent appliance operations. Screening consists of computing the arithmetic mean and the variance of the readings of the batch at hand. If the variance is less than a predetermined threshold level, the mean of that batch of temperature data is forwarded to the memory for subsequent use. If the variance exceeds that predetermined threshold level, the data are expunged and not used. When the number of rejected contiguous batches of data exceeds a predetermined number, an alarm is provided to alert an operator that the system is noisy.

Abstract: A moisture-sensing circuit for a clothes dryer separates the moisture-sensing and timing functions in a way that minimizes undesirable interaction and reduces effects of tolerances in components, temperature, and supply-voltage. Separate comparators are provided for (1) the resistance of the moisture sensor as compared with a first threshold and (2) the time since occurrence of the most recent moisture signal that exceeded the first threshold, as compared with a second threshold representing a predetermined delay.

Abstract: A refrigeration system employing a mechanical thermal expansion valve with a self-heated thermistor sensing saturation temperature at the high pressure inlet. A microprocessor based controller compares the sensed temperature with stored limits and provides output signals to a relay for cycling the condenser fan responsive to high side pressure means are provided for varying the current through the thermistor for operating same in the non-self heated mode to sense actual refrigeration temperature for generating a control signal to disable the compressor clutch when refrigerant temperature exceeds desired low limits.

Abstract: A refrigeration system employing a mechanical thermal expansion valve with a self-heated thermistor sensing saturation temperature at a high pressure inlet and a second thermistor sensing saturation temperature at the evaporator outlet. A microprocessor based controller compares the sensed temperature with stored limits and provides output signals to a relay for cycling the condenser fan responsive to high side pressure and the compressor clutch responsive to the low pressure side temperature. For low pressure drop evaporators, the second thermistor may be disposed at the evaporator inlet.