Abstract: A power stealing circuit provides operating power for a environmental control such as a thermostatic control while controlling the current in a power supply line to a load in response to the cycling output of the environmental control. A pair of power FETs are connected to the series power terminals, and the gates are controlled by logic and phase timers. FETs are turned off at the end of a phase, while a small amount of power sufficient to operate the control and circuitry is diverted to a power storage circuit, then the FETs are turned back without substantial interruption to the load. A preferred embodiment uses a bi-directional charge pump to transfer power between low- and high-voltage power storage circuits. The circuit can operate with symmetrical or nonsymetrical AC or DC loads.

Abstract: A bi-directional DC/DC voltage converter having first and second input/output terminals for respectively receiving on a mutually exclusive basis uni-directional current at first and second voltages. A charge pump circuit connected between the first and second input/output terminal, depending on which voltage is supplied, converts that voltage to the other voltage.

Abstract: A circuit for detecting presence of a flame receives a flame signal from a standard photocell positioned to receive radiation from the flame and digitally processes the amplitude variations in the photocell's output to sense for the presence of frequencies near a frequency which is characteristic of a flame. The frequencies substantially higher than the characteristic frequency are filtered from the signal, and the remaining signal is sampled at a frequency which is preferably four times the characteristic frequency. The samples are converted to digital values and processed using a discrete Fourier transform. If the value resulting from the transform operation exceeds a preselected value, presence of a flame is essentially certain. Such digital processing allows use of a dedicated microcircuit or a microprocessor for the flame sensing function and avoids the need for many large discrete components.

Abstract: A circuit for cutting a "notch" in an alternating current supply waveform with the minimization of dissipated power comprising a pair of GTO's so poled to conduct current therethrough and also through a pair of power consuming diodes when the switches are "on" during alternate half cycles, the switches being turned "off" at the start of the "notches", and the current is resumed thereafter by a pair of oppositely poled SCR's which are turned "on" and which bypass power diodes so as to conserve power.

Abstract: Apparatus for use with a fluorescent light dimming circuit to delay the application of power to the lamp for a first time period sufficient to allow the electronic components to stabilize and thereafter to delay any dimming signal to the lamp and, instead, apply full power to the lamp for a time period sufficient to allow the filament of the lamp to warm up.

Abstract: A dimmer for a fluorescent light in which the fluorescent light is supplied with an electrical signal having a varying magnitude, the dimmer positioning a notch of reduced signal magnitude within the electrical signal for controlling the illumination level of the fluorescent light wherein the illumination level is dependent upon the position of the notch within the varying electrical signal.

Abstract: A circuit for use with the dimming control of a fluorescent light in which a "notch" is created and positioned to vary the power to the inductive ballast and the circuit including a pair of gate turn-off thyristors operable to supply a current path for stored energy in the inductive ballast only during the notch.

Abstract: A two wire rechargeable battery powered electric time controlled thermostat apparatus adapted to be connected by two wires to a source of alternating current voltage and control apparatus for controlling the supply of temperature condition medium to the space wherein the thermostat is located with a rectifying circuit means in the thermostat apparatus for recharging the battery from the source over the two wires.

Abstract: A flow sensor having adjustable sensitivity includes a differential pressure sensing element located in an internal compartment within a rotatable cylinder. The compartment is connected between diametrically opposite fluid ports on the surface of the cylinder by fluid channels. In one embodiment, the sensor is located on a diaphragm partitioning the compartment into a first and a second chamber with the sensor being responsive to a distortion of the diaphragm induced by a differential pressure. In a second embodiment, the sensor is a flow sensor and is arranged to monitor a fluid flow through the compartment induced by a differential pressure. The cylinder is rotatable on an axis at located right angles to a fluid flow thereacross whereby the ports are selectively located at a desired angle with respect to the fluid flow path. The cylinder is located within a fluid-tight housing having a fluid inlet and a fluid outlet arranged to direct a fluid being monitored by the sensor around the cylinder.

Abstract: A power supply usable with various size loads has an input circuit receiving pulses of voltage at 25 kilohertz. The pulses are modulated in width depending upon the input to a pulse-width modulation IC receiving inputs indicative of the output voltage and current delivered to the load. A backup current limiting circuit comprising a transistor which is biased by the voltage to the load, limits the signal to the pulse-width modulation IC to limit the width of the pulse to maintain the output current within limits.

Abstract: An enthalpy control circuit has a humidity responsive capacitive element in one leg of a bridge circuit and a temperature responsive resistance element in another leg. The circuit is powered by a pulsating DC voltage of 1 kilohertz frequency for providing DC output, from an integrator connected to the output of the bridge circuit, indicative of enthalpy. A feedback from an integrator output to the bridge circuit is provided by chopping the DC output into appropriate AC for rebalance. Another feedback circuit around an amplifier provides a reference point compensated for offset voltages brought about by conditions such as temperature affecting circuit components.

Abstract: A humidity responsive circuit is adapted to be connected to a thermostat to provide a humidity comfort offset to the thermostat. The humidity comfort offset circuit can be added to a retrofit item or could be added during the manufacture of an electronic thermostat which has a bridge in its input for measuring the temperature. The humidity comfort offset circuit have an output range with at least one humidity value being equal to the balance value of the bridge.

Abstract: A humidity element circuit calibration arrangement utilizing a humidity responsive capacitive element is provided for. A single signal generator arrangement provides two opposite phases of the same voltage to energize the circuit thereby allowing for simple calibration by the adjustment of a single resistance element.

Abstract: An electric damper motor drive with a backup power pack is disclosed comprising a reversible electric motor operable in first and second opposite directions in response to first and second distinct forms of electrical energization, respectively. A primary power source normally supplies electrical power to energize the motor in response to a sensed environmental condition. A backup power pack is responsive to the absence of power from the primary power source to supply the first form of electrical energization to drive the motor in the first direction to a predetermined position.

Abstract: A means for physically opening and closing electrical contacts to check their integrity for safety systems is provided. Contact means are cycled by the movement of two relatively moveable parts and the actual physical operation of the contacts is checked. The system is latched in its operable position by reversing the energization of an electromagnet which was used to unlatch or start the checking sequence.

Abstract: By means of a moveable insulating member that has two electrically conductive areas that are separated by a nonconductive area it is possible to build a mechanically controlled electronic thermostat. The temperature sensing is accomplished by a temperature responsive means that moves generally parallel to the conductive area, and functions as a pair of differentially energized variable capacitors that drive an electronic circuit when any unbalance occurs. This unbalance is indicative of a disagreement of the set temperature with the control temperature.

Abstract: A condition control system utilizing digital anticipation involving periodically filling a counter from a relatively high frequency source in response to a first frequency signal. The relatively high frequency signal is fed in a controlled manner into an anticipation cycle counting means to provide for digital anticipation in a condition control system. The system has been specifically disclosed as a temperature control system or thermostat. The system also provides for a bypass means to reset the system when a set point change has been made. A degulping circuit has been provided to eliminate instability at very high and very low loads.

Abstract: A low dissipation two wire thermostat for connection to an alternating current source and a load to be controlled wherein, on alternate half cycles of the source, a rechargeable DC source, is recharged and, on the opposite half cycles, a capacitor is charged to control a comparator's output so as to cause a switching action that prevents high power dissipation in the thermostat for both the "on" and "off" conditions.

Abstract: A condition control device has been shown as a thermostat that not only controls, but draws power from the same two conductors. The drawing of power from the control conductors is accomplished by momentarily opening the control circuit and allowing a charge to be stored on an energy storage means. The control of the operation of the switching relies on a voltage controlled oscillator that is synchronized to the line frequency during the slight period of time that the solid state load switch means that controls the load is deenergized.

Abstract: An energy saving thermostat adapted to be connected to a remote temperature conditioning apparatus for controlling the temperature of air in a space maintains a first temperature during a first time period and a second energy saving temperature during other time periods of the day. The thermostat has a visual indicating means so that when a manually settable switch is pushed, a time interval counter means is energized for indicating and storing a series of pulses each indicative of an hour of setback time into a storage means. The thermostat also has a review button for reviewing the stored time by pulsing the visual indicating means for the number of hours of the time period energy saving temperature.