Abstract: A solid state switching circuit using a capacitive feedback that creates a positive differential. This positive differential overcomes any half-wave operation of the solid state switches caused by lack of symmetry in its gating circuit.

Abstract: A condition control system in the form of a fuel burner control means is disclosed. A group of relays and their associated contacts are used to control the burner means. The status of the relays and their contacts are continuously checked by a control logic means by having the voltage on key relay output contacts fed into the control logic means through isolated signal transmission means. All of the relays are capable of being deenergized in the event of the need for safety shut down as determined by the control logic means.

Abstract: A control logic means or microcomputer controlled burner control system has been disclosed. The system utilizes a safety relay that has contacts that are in series with all of the other loads for the system. The safety relay contacts are checked prior to operation of the system to verify their ability to open the load circuit. The operation of the electronics for the control of the safety relay are regularly checked during the operation of the system by a combination of feedback circuits from the electronics, and from the final control element for the various loads.

Abstract: A humidity sensor utilizes a conductive polymer film that normally exhibits a variable resistance characteristic. The polymer film also exhibits a humidity responsive function that can be utilized while the temperature responsive function is balanced out. The device is capable of a high level of calibration by the use of laser trimming of the conductive polymer film resistors.

Abstract: Two field effect transistor device means are utilized in conjunction with a special type of transformer having a low impedance primary winding and a high impedance primary winding to energize a secondary circuit to supply power for operating the electronics. The energy storage means for the field effect transistor device means is kept charged either directly from the line or through a voltage in the primary windings of the special transformer when the load switching field effect transistor device means is conducting.

Abstract: Field effect transistor device means of the bilateral insulated gate type have been disclosed as power switches that are capable of being switched between a conductive and a non-conductive state. A means for deriving energy for the operation of the field effect transistor devices has been disclosed which is wholly independent of current drawn through the substrate electrode means of the field effect transistor devices themselves, and which is capable of use in multiple control systems applications.

Abstract: A resistive fluid or boiler water type of detecting system has been disclosed. A single conductor type of probe having a plurality of conducting regions that are capable of conducting a bidirectional electric current in either a full bidirectional mode or in a unidirectional mode has been disclosed. The single probe element is capable of three separate and distinct states of operation. The first state is when there is an absence of current, the second is when there is a unidirectional portion of the bidirectional current flowing, and the third state is when the full bidirectional electric current is allowed to flow. An output device is responsive to these three states to provide different types or levels of control.

Abstract: A fuel burner primary control with a pre-purge and extended ignition function has been disclosed. The system has been disclosed as an oil burner which utilizes a voltage regulator to insure that adequate power is supplied to the device and with a time delay on the application of potential to the ignition and oil source to allow for a pre-purge interval. The ignition source is also time delayed to insure a stable flame before the ignition is deenergized.

Abstract: An oil burner ignition circuit using a relaxation oscillator is disclosed. The step-up transformer has a tertiary winding magnetically coupled to a primary winding. The tertiary winding and a diode controls the dissipation in the circuit, and the recovery of energy to a capacitor of the relaxation oscillator.

Abstract: A fuel ignition system that uses a high voltage spark generator and a flame rectification detecting circuit is disclosed. The system utilizes a voltage clipping means in the form of a neon tube to prevent the high voltage of the ignition system from interferring with the operation of the flame detection system even though both systems use a common spark gap.

Abstract: A flame responsive control circuit means has been disclosed which responds to the flame in a burner. The response is to the sudden rate of change of the resistance or impedance of a photocell upon the loss of flame. The two embodiments disclosed both utilize a rate of change sensing means to determine that a loss of flame has occurred. If a loss occurs, ignition is reinstituted immediately and the system either operates normally or locks itself out in a safety shut down.

Abstract: A safe start check circuit for a fuel burner is disclosed. Two relays are arranged to insure proper start and to protect against component failure. Delays in operating the relays, and a normally closed control relay contact serve to both prevent relay races and provide protection against a solid state switch means failure.

Abstract: A fluid level control circuit with a safety test function for a boiler water level probe of a fail safe type is connected to a field effect transistor controlled amplifier having a well defined threshold of operation. A safety test switch means is provided to pull the amplifier's input down below the threshold point, but not to a shorted condition. By observing the output of the system it is possible to determine whether the fluid level detector is properly installed, and whether the amplifier has had any type of unsafe operating failure.

Abstract: An electronic control system for safely operating a pair of redundant solenoid type valves is disclosed. The system utilizes an alternating current potential for energizing the valves. The first valve is energized across the applied potential and then is placed in series with the second valve. The series combination is selected so that once the valves are energized they will stay energized in the series configuration.

Abstract: A time proportional control means, shown as a temperature control system, utilizes an expanded time constant arrangement with a unidirectional type of digital counter. The control system also utilizes a pulse generating means that is linked to the set point control for the system. Any substantial change of the set point causes the pulse generating means to generate pulses that are used by a pulse responsive circuit to insure that the counter for the system is adjusted to cause the output of the system to correspond with the new set point position.

Abstract: The voltage that occurs across the run capacitor of a permanently split capacitor type motor when the motor is in operation is quite high compared to the voltage that is present if the motor is stalled. These different voltage conditions are sensed through the use of a voltage pickoff to control an optical type isolation circuit which in turn controls a switch means to energize a fault indicator.

Abstract: A condition responsive time proportional control means which has a relatively fast time constant when operating in its proportional band has the time constant expanded by means of a digital counter. The counter is repetitively switched by the condition responsive means and counts the switched operation. During the period that the switched operation is occurring, the time constant is expanded by simultaneously counting pulses from a pulse generating means.

Abstract: A multi-stage condition control system of the time proportional type is shown. The control system utilizes a counting means as part of the anticipation for system control. The counting means counts during the time the control system is within its proportional band. When the control system moves outside of the proportional band, the counting stops. A count detection circuit senses the absence of counts thereby indicating that the system is outside of the proportional band. The absence of counts is then used to increase or decrease multiple stages of condition control equipment to bring the system back within the proportional band.

Abstract: A fuel burner safe starting system which utilizes a pilot valve and a main valve is disclosed. A flame detection system operates in conjunction with a relay which properly ignites and operates the fuel burner system. In the event of a failure which improperly energizes the relay, the safe starting system prevents the fuel valves from opening.

Abstract: A condition responsive time proportional control means which has a relatively fast time constant when operating in its proportional band has the time constant expanded by means of a digital counter. The counter is a resettable unidirectional type counter that has two counting channels. The main counting channel provides for the counting function during the normal cycling of the system when in the proportional band. A second channel in the counter acts to enable to the counter rapidly in the event that there is a disruption of the counter when the condition responsive system has been outside of the proportional band.