Abstract: A temperature controller with a remote sensor having a high temperature cutoff with circuit means to prevent operation of the unit if tampered with to bypass a safety function. A remote sensor has a thermal fuse and diode feeding a pulsating D.C. voltage to a control circuit having a capacitor and an impedance means to which pulsating D.C. is fed. If the sensor unit is bypassed the thermal fuse in the controller burns out to render the controller inoperative.

Abstract: An electronic control device utilizes a plurality of conductive areas on an associated printed wiring board to create integral dew sensors. The dew sensors are created by providing parallel conductive surfaces that are connected in turn by a resistor to a high impedance switch in the form of the gate of a field effect transistor. In the event that moisture vapor or dew is present in the control device, a conductive path is created that causes the control device to shut down in a safe or alternate mode from the normal mode of operation.

Abstract: A hot surface ignitor element is functionally checked for continuity and operating temperature. This check is accomplished by initially energizing the hot surface ignitor element and then switching it as a single ended element into a series circuit with a source of potential. The potential is applied between the hot surface ignitor and an electrode which is connected back to the source of potential. If the hot surface ignitor has come up to ignition temperature a flame rectification signal is simulated.

Abstract: A control device for controlling temperature conditioning apparatus is connected to a thermostatic switch means having a circuit requiring a small current to maintain the circuit active during the open cycle of the thermostat switch means. A positive temperature coefficient resistor is placed in parallel with the input circuit of the control device to provide a low input impedance to the control device for maintaining the small current without activating the control device. During the operation of the thermostat with the switch closed, a larger current to the positive temperature coefficient resistor causes the resistor to increase in temperature and thus its impedance so the wattage dissipated by the PTC resistor is reduced to minimize the heat dissipation and thus the temperature of the control.

Abstract: With the addition of a conductive means in the form of a grounded ring or member placed at the insulator means of a high voltage spark electrode structure, the required break down voltage of the spark gap can be reduced. The conductive means typically would be a ring encircling the insulator means of the electrode structure and would provide a ground as well as a mechanical support near the end of the insulator means of the electrode structure.

Abstract: A hot wire type of gas ignition system uses a negative temperature coefficient resistor-ignitor element that is deenergized after ignition has occurred. The ignition and safety monitoring of the circuit is accomplished by a second flame detector means, and the flame responsive circuit that has been disclosed in a flame rectification circuit.

Abstract: A fuel burner control system that has a fail safe mode of operation utilizes a flame sensing means that controls two separate signal processing circuits that have two different threshold levels of operation. Each of the signal processing circuits controls a separate switch means and these switch means are interrelated to ensure that a pilot valve and main valve are opened in sequence and that a pilot flame is properly burning before the main valve is opened. If the flame sensing means for the device senses any abnormality, the interrelationship of the output circuits prevents the main valve from opening.

Abstract: A timer and control circuit using a field effect transistor that is operated in three different current carrying conditions or operating modes is disclosed. The three operating modes are used to establish two successive timed intervals for a prepurge and a trial for ignition for a fuel burner.

Abstract: A fail safe digital timer is provided by having a pair of similar counters counting the output of a single clock means. The clock means provides clock pulses and complimentary clock pulses to the two counters and the outputs of the counters are compared. If the two counters are properly operating the comparison will provide a continuous stream of pulses at a frequency equal to the frequency of the clock means for the timer. The failure of any of the components in the system cause the output of the comparator means to either become a constant logic 1 or a constant logic 0.

Abstract: A spark generator of the relaxation oscillator type operates on only one half of the cycle of the applied alternating current. By providing a gating circuit that triggers through a threshold switch means from a capacitor charge, it is possible to fire a silicon controlled rectifier on the same half cycle as the charging of an energy storage capacitor. The circuit can be operated by means of a diode and switch, or by an asymmetric current conducting element such as a silicon controlled rectifier.