Abstract: A spark ignition system for a pilot flame uses a flame sensing rod to switch ac voltage from a spark generator to a main valve, thereby providing positive suppression of spark generation once the pilot flame is sensed. A main oscillator activated by a flame sensing signal is provided to operate a switch for this purpose. Should the pilot flame be extinguished, the switch automatically reverts to its first state, thereby closing the main valve and reactivating the spark generator. The entire system is operative only when ac voltage is present from a thermostat demanding heat. The pilot valve connected directly to the thermostat is open to emit gas whenever there is a demand for heat.

Abstract: A direct spark ignition system is provided with an improved spark generator powered directly from a low voltage dc source through an inverter controlled by a gated oscillator. The inverter is comprised of a step-up transformer having its primary winding connected between the power source and a common-emitter transistor having its base electrode connected to an output of the oscillator. A rectifier couples the secondary winding to a storage capacitor, and a spark discharge timing means controls periodic discharge of the storage capacitor into a spark electrode. A diode between the collector of the switching transistor and the storage capacitor is poled to couple back EMF of the transformer primary winding into the capacitor, thereby not only protecting the collector of the transistor but adding the back EMF energy to the charge in the capacitor for higher efficiency. High spark rates (nominal 750 sparks per minute) are achieved.

Abstract: An improved system including a circuit for igniting a pilot burner each time heat is called for by a thermostat. The main burner is ignited by the standing pilot upon detection of pilot ignition. Trial ignition over a limited period of time is provided. Main and pilot oscillators each having only two transistors are employed to actuate respective main and pilot valves. Each oscillator is of a new type requiring few electronic components.

Abstract: A system including a circuit for igniting or reigniting a pilot burner in a gas fired device each time heat is called for by a thermostat or otherwise. The main burner is ignited by the ignited pilot upon detection of pilot ignition. A sequencing interlock is provided for trial ignition over a limited period of time. An output of a main valve control acting through the sequencing interlock causes sustained actuation of a pilot valve control if the main valve control is actuated.

Abstract: A system for trial period ignition of a fluid fuel burner having an oscillator with a gate in the feedback path thereof, the oscillator providing power to a burner fuel valve and to a spark generator, wherein oscillator operation is sustained after the period only upon flame detection which keeps the oscillator feedback path gate closed.