Abstract: Gas fired donut cooking system for automatic cooking of donuts featuring a low voltage controlled gas fired tube for heating of the cooking oil. Operation is powered from ordinary household current or can be powered by a storage battery and a power inverter at a remote site where household current is unobtainable. Propane or butane gas is supplied from a bottle.

Abstract: Disclosed is a liquid level controller that uses a pair of vertically spaced thermistors to control a switching means to turn a pump on when a sufficient depth of liquid is present and to turn the pump off before the pump runs dry. Such a device is ideally suited for applications such as "stripper" oil wells. The present invention uses thermistors in the self heat mode and senses the changes in the resistance between a thermistor exposed to air and one submerged in liquid, the latter increasing resistance because it is far more efficient in transferring away heat generated by the thermistor. The change of resistance when the liquid level covers the higher of the thermistors is detected by the use of comparators which selectively turn on a driving transistor. Turning the transistor on activates a coil which throws a relay switch and activates the control circuitry of the pump motor.

Abstract: An emission control circuit for an internal combustion engine having a voltage generating circuit connected to a source of direct current energy at a first potential for generating an output voltage of a substantially higher potential, the voltage generating circuit including energy storage means coupled to the output of the voltage generating means for storing an electrical charge. A triggerable switching means is provided for coupling the energy storage means in series with the primary winding of an induction coil, and triggering means responsive to the opening and closing of ignition breaker points is provided for applying triggering signals to the triggerable switching means. The triggering signals accommodate discharging of the energy storage means through the primary winding for a certain predetermined time period. A comparator circuit is provided which includes two semiconductor amplifier circuits, each having a pair of output electrodes and a control electrode.