Abstract: An ignition/reignition circuit (10) for a gas burner (12) having separate flame sensing and ignition electrodes. The flame sensing electrode (25,30) trips a switch (Q1) upon transition from sensor output signals indicative of the sensed presence of a flame to a sensed absence. The switch is coupled to a spark generator circuit which includes a spark electrode (16) for reigniting the burner in the event of flame failure.

Abstract: At least two sets of point-to-flat spark electrodes are connected for high voltage excitation from a pulse source such as individual secondary windings of a common transformer. Each secondary winding has one end connected to one of the pointed electrodes, with the other end of the winding commonly grounded with the flat electrode to provide common polarity to all pointed electrodes.

Abstract: A refrigeration control system with self-adjusting defrost interval is provided. The system includes an improved control circuit including an external comparator and a microprocessor having a compressor output drive function and a defrost output drive function. The comparator is linked with the microprocessor with circuit elements for detecting the time period of a defrost operation, comparing the time period with predetermined defrost period limits, generating an output control signal in response to a predetermined relationship between the time period and the limits, and adjusting the defrost interval in response to the control signal whereby the defrost operation is maintained within a preferred preselected time period.

Abstract: An automatic resetting anti 2-BLOCK condition crane warning system gives audible and visual warning of an imminent 2-BLOCK condition and prevents occurrence of an actual 2-BLOCK condition by means of a control output signal. The warning system is further operable to permit override of the indication of and control against the 2-BLOCK condition. Three distinct audible and visual indications are provided for NORMAL, 2-BLOCK, and OVERRIDE system states. The system is further operative to automatically reset to a NORMAL state from either a 2-BLOCK or OVERRIDE state upon sensing a transition from a 2-BLOCK condition to a NORMAL condition.