Abstract: A system for monitoring a percentage of filter life remaining of a filter assembly of filter-fan devices. The system uses a single thermistor that is operated in two separate modes for monitoring the filter assembly. The thermistor is positioned in the airflow of the filter-fan adjacent to the air outlet. A first current is applied to the thermistor for determining the temperature of the airflow from a first thermistor voltage. The first thermistor voltage is responsive to the first current applied to the thermistor. A second current that is greater than the first current is applied to the heat the thermistor. The temperature of the thermistor is determined from a second thermistor voltage which is responsive to the second current applied to the thermistor. The percentage of filter life remaining of the filter assembly is determined from the temperature of the airflow and the second thermistor voltage.

Abstract: A vaporizer that adjusts to the conductivity of the water used in the vaporizer, and that also adjusts to changes in the conductivity of the water while in operation, thereby decreasing warm-up time and maintaining a relatively constant boiling rate and rate of steam production. The vaporizer includes hardware circuitry or other logic that maintains constant power supplied to the electrodes of the vaporizer to decrease warm-up time, and adjusts the current supplied to the electrodes while the vaporizer is in operation and after the warm-up period to maintain a relatively constant boiling rate and rate of steam production.

Abstract: A vaporizer that adjusts to the conductivity of the water used in the vaporizer, and that also adjusts to changes in the conductivity of the water while in operation, thereby decreasing warm-up time and maintaining a relatively constant boiling rate and rate of steam production. The vaporizer includes hardware circuitry or other logic that maintains constant power supplied to the electrodes of the vaporizer to decrease warm-up time, and adjusts the current supplied to the electrodes while the vaporizer is in operation and after the warm-up period to maintain a relatively constant boiling rate and rate of steam production.

Abstract: An air purifier unit having a mounting assembly that allows the mounting of the unit underneath a cabinet or on any like flat surface. A cartridge filter is provided and easily ejected or replaced through a filter door in the face of the enclosure. A motor speed indicator circuit enables the user to visually monitor the speed of the motor and blower. Air is drawn into the housing of the unit through an intake opening on the bottom surface of the housing, forced through a cartridge filter, and expelled out an air exhaust opening.

Abstract: A heater, humidifier or fan has a control circuit including a microcontroller having an algorithm for controlling power to the appliance. The power to the appliance is varied in accordance with a target temperature/humidity signal and an actual temperature/humidity signal. Preferably, a sensor electrically connected to a clock oscillator input of the microcontroller is used to vary the clock oscillator frequency in response to changes in ambient temperature/humidity. The frequency of the clock oscillator varies in response to changes in temperature/humidity and the microcontroller in response to the frequency of the clock oscillator variably controls the power to the appliance.

Abstract: A gas drying method is disclosed in which gas streams are dehydrated to low dew points by contacting the wet gas with a dry liquid desiccant, with the liquid desiccant regenerated by heating it in a reboiler containing an internal reboiler vapor condenser and stripping it with a stripping agent that is dried with solid desiccant.

Abstract: A heating pad controller is provided which varies the duty cycle during which power is applied to a heating pad heating element. In one embodiment according to the present invention, an oscillator circuit is used to vary the off-time of the duty cycle, with the on-time portion being fixed. User control of the off-time is provided by way of a rotary control knob connected to a potentiometer. The potentiometer is part of the oscillator circuit and is used to vary the resistance through which a capacitor in the oscillator circuit charges up. The output of the oscillator circuit is used to control the gate of a silicon controlled rectifier (SCR), which acts as a power switch through which power is applied to the heating element. During power up, the oscillator circuit is overridden and a continuous control signal is applied to the SCR to provide constant power to the heating element to thereby achieve rapid heating.

Abstract: A gas drying method is disclosed in which gas streams are dehydrated to low dew points by contacting the wet gas with a dry liquid desiccant, with the liquid desiccant regenerated by heating it and stripping it with a stripping agent that is dried with solid desiccant.

Abstract: A low cost heater element is disclosed which is formed of a wire wound mica paper substrate and a mica paper cover and a low cost diode acting as a negative temperature coefficient of resistance NTC temperature sensor. A control circuit provides power to the heater element in proportion to the line voltage. As a result, a light weight, low cost heater element is employed for various line voltages available throughout the world. The system employs digital logic to achieve temperature sensing, power sensing and indication that the system is on and operating at the correct temperature.

Abstract: Sinusoidal timing reference signals, each of which is associated with a different suppresed-sync scrambled-priority television channel signal, frequency modulate associated carrier frequency signals for producing modulated carrier signals that are combined with a continuous wave (CW) sinusoidal carrier frequency signal. After low-pass filtering to block harmonic frequencies that may interfere with the video carriers of composite television signals, only the fundamentals of the CW and modulated carrier signals are combined with non-scrambled and/or scrambled composite television signals for transmission to subscriber's equipment. In a descrambler at a subscriber location, the CW carrier signal is mixed with the modulated carrier signals to produce frequency modulated IF signals containing timing information for associated priority television channel signals.

Abstract: A tactile matrix switch has a planar electrically conductive layer dielectrically spaced between contacts of individual switch elements and an actuating mechanism such as a finger on the body of a human being who may carry an electrostatic charge. Some switch contacts are electrically connected through external circuitry to ground. The conductive layer is also electrically connected to ground. When a human operator carrying an electrostatic charge brings his finger near the face of the matrix switch for applying a tactile force to actuate an individual switch element, the conductive layer electrically conducts the electrostatic charge to ground and away from the switch contacts for protecting the electrical circuitry connected to the latter. In one embodiment, the conductive layer is electrically conductive printer's ink, having a resistivity of less than 50 k ohms per square, that is silk screened onto the back of a face plate of the matrix switch.