Abstract: A temperature sensing device employs a resonant polysilicon beam, in combination with electrical circuitry for oscillating the beam at its natural resonant frequency, to sense changes in temperature. The resonant beam is formed as part of a silicon layer, and the silicon layer is in direct contact with a dissimilar material. In one version of the device, the silicon layer is deposited onto a sapphire substrate by low pressure chemical vapor deposition. In another version, the beam is part of a polysilicon layer deposited onto a silicon wafer substrate. The silicon substrate is thinned, then thermoelectrically bonded to a borosilicate glass substrate. In still another version, the silicon substrate is selectively thinned and has deposited thereon a TCE mismatched material. In all versions, temperature is sensed based on a thermal mismatch of the two dissimilar materials.

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 method and system for improving indoor air quality by controlling the circulation of air by a system fan of a conventional environmental control system in order to achieve a minimum circulation cycle. The method and system prevent nuisance short cycling of the system fan by extending the circulation cycle when the method and system predict the system fan will be activated by the environmental control system for heating or cooling shortly after the termination of the controlled circulation.

Abstract: A device for converting the rotation of a spindle nut into a force-related linear translation of a threaded spindle in an electromechanical valve actuator, the spindle being formed with longitudinal grooves in which clamping hooks are located. Hooked ends of the clamping hooks engage retainer rings of which one retainer ring abuts a collar on the spindle nut or abuts a stationary abutment, respectively, and another retainer ring restrains one end of a spring, the other end of which is restrained by a stationary abutment or the collar.

Abstract: A humidity sensing circuit uses a humidity sensitive capacitor as a circuit element in an RC control network for a timer/multivibrator circuit. As the voltage on one plate of the capacitor swings between charge and discharge voltage limits and corresponding triggering voltage values for the timer/multivibrator, the other plate of the capacitor is held at a voltage substantially midway between the charge/discharge voltage limits to thereby cancel out any time averaged net DC component on the capacitor, to reduce stress thereon and extend its life. A power-down feature is disclosed for removing all voltage across the capacitor between sensing intervals.

Abstract: A self-checking temperature sensing circuit in which temperature sensitivity is provided by first and second resistive elements having positive and negative temperature coefficients respectively. The resistive elements are connected in parallel current paths, one of which includes a diode for allowing only unidirectional current flow. The resistances of the restrictive elements are determined by a circuit which periodically reverses the polarity of a voltage applied across the parallel paths.

Abstract: An electromechanical actuator-operated pressure regulator for supplying control pressure for a diaphragm-operated gas control valve, the actuator also operating an on-off control valve for the gas valve. A passageway including a pressure adjusting device for supplying a minimum gas valve output pressure extends from the downstream side of the on-off valve to the gas valve outlet.

Abstract: A solid state power switching circuit for alternating current loads, in which operating power for the circuit is diverted from the switched current during power stealing intervals self-synchronized with the alternating current waveform. During periods in which current to the load is commanded, a load current switch is maintained in a low impedance state except for the duration of a short power stealing interval each half-cycle of the supplied alternating current. Self-synchronization is achieved with a current detector which senses whether or not the magnitude of the current diverted during each power stealing interval exceeds a current threshold, and pulse generator logic which shifts the power stealing intervals in time relative to the alternating current waveform in response to the previously sensed current magnitude.

Abstract: A manufacturing method for control devices which incorporate potentiometers whose resistance characteristics other than linearity are subject to unit-to-unit variations, and in which a wiper positioning knob in cooperation with a fixed scale indicates the set point for the controlled parameter, the method involving mounting the potentiometer in its theoretically ideal orientation in the device, affixing the knob to the potentiometer so that a pointer thereon points to the desired location on the device for a predetermined point on the scale when the wiper is positioned to control the parameter to the set point corresponding to the predetermined point on the scale, and marking the scale on the device so that the predetermined point on the scale is at its desired location on the device.

Abstract: A fluorescent light control circuit usable with a transformer relay for providing electric current pulses of alternating polarity in response to successive operations of a two position electromechanical switch, the circuit including first and second controllable current paths operable to conduct current in opposite directions only, the active path being operable to conduct current only momentarily following repositioning of the switch.

Abstract: A burner control system for controlling gas flow to a burner in response to a pressure differential indicative of air flow to the burner, the pressure differential being impressed across a diaphragm which actuates a bleed valve controlling the pressure on one side of the diaphragm actuator of a fuel valve. The bleed chamber is connected to the outlet of the gas valve and the low pressure side of a pressure differential through separate flow restrictors.

Abstract: A flame rectification type flame sensor circuit and method in which a generator injects periodic pulses of alternating voltage into a flame region, the voltage across the flame region being processed by a filter/amplifier which, in proper operation, produces a non-zero output signal only during the time a flame is present and a pulse of alternating voltage is being supplied by the generator. Final indication of a flame is produced only if a non-zero output signal occurs during the time a pulse of alternating voltage is being supplied, and not during the time between successive pulses of alternating voltage. Failure of an electrical component in the filter/amplifier is indicated if a non-zero output signal occurs during the time between successive pulses of alternating voltage.

Abstract: A fuel valve and ignitor control system in which pull-in current for a fuel valve operating on rectified alternating current is supplied through a first normally open relay whose coil is connected in series with normally open contacts of a second relay and an intermittently operating hot surface ignitor. Normally closed contacts of the second relay are connected in series with the ignitor and the fuel valve through a holding resistor, whereby actuation of the second relay provides unrectified alternating current to the ignitor and actuates the first relay to provide pull-in current to the fuel valve, and whereby deactivation of the second relay provides holding current to the fuel valve through the ignitor.

Abstract: A convertible two-stage pressure regulator in which a main valve regulates fluid flow between an inlet and outlet in response to a control pressure produced by a servo regulator valve, the control pressure depending on outlet pressure and the force provided by a regulator spring to a diaphragm carrying a servo regulator valve closure element. Compression of the regulator spring is controlled by a solenoid armature in a plunger assembly which is selectively positionable by a selector knob to obtain higher or lower regulator spring force. Adjustable stops provide for individual adjustment of low and high outlet pressures for each of two pressure ranges. Substantially identical air gaps in the magnetic circuit of the solenoid are provided for both pressure ranges by a magnetic pole piece in the plunger assembly which extends beyond the solenoid coil in one direction and a solenoid armature which extends beyond the solenoid coil in the opposite direction.

Abstract: A microprocessor watchdog circuit in which a voltage less than a reference voltage is supplied to a comparator substantially only in response to a pulse train status signal having a predetermined repetition rate. Repetition rate sensitivity results from a charge pump connected to receive the status pulse train through a series connected resistor and capacitor having a suitable time constant. The comparator output terminal, at which a reset signal is produced, provides a low impedance path to ground if the charge pump removes charge from a second capacitor more slowly than charge is supplied thereto through a charging resistor, thereby increasing the voltage supplied to the comparator.