Abstract: A protective circuit for a solid state static inverter which employs two groups of switching transistors coupled in push pull to the output transformer. If trigger pulses to one group of switching transistors is lost, the protective circuit senses the missing trigger pulses and disables both groups of switching transistors. In normal operation the protective circuit assures that only one group of switching transistors may be rendered conductive at any given time.

Abstract: A releasable connector mechanism having two parallel side plates and first and second shafts extending between the plates on opposite sides thereof. At least one of the shafts is freely rotatable and has a pair of spaced pivot arms attached thereto. The rotatable shaft has a groove or cam surface extending longitudinally along its surface.A load carrying fulcrum plate having a concave cylindrical pivot surface not more than 180.degree. on one end thereof is inserted between the side plates with the pivot surface supported on the nonrotating shaft. The other end of the fulcrum plate has a swinging latch attached thereto which pivotally contacts the other end of the fulcrum plate and also pivotally contacts the cam or groove in the rotatable shaft.In its set condition the fulcrum plate is held between the side plates by the nonrotatable shaft and by the swinging latch.

Abstract: A simple inexpensive slide switch is disclosed having a unitary plastic slide member serving the dual function as a switch housing and actuator. The plastic member is slidably mounted to the insulator base member by flexible side skirts having barbs extending inwardly and disposed in sliding engagement with the base member undersurface. The flexible side skirts and base member have complementary boss means and boss receiving means to provide detent type operation.

Abstract: An ejector for produce sorting apparatus including a drooping or sagging sheet of substantially air impervious material suspended in front of an air nozzle and adjacent the path of articles of produce moving along a free fall path. Upon occurrence of a reject signal from produce grading apparatus, an air blast impinges against the sheet to extend it to a taut condition into the free fall path to eject an article of produce.

Abstract: Slide switch in which sliding member which retains sliding contact has side skirts with barbs at bottom edge. Barbs engage and slide on bottom surface of insulator strip on which stationary contacts are mounted.

Abstract: An optical system for use on produce graders to enhance intensity and uniformity of reflected light directed onto color detectors.

Abstract: Protection circuit for preventing high surge current on start up of static inverter.

Abstract: A synchronizing system is provided to produce gating pulses which occur only when a pocket between adjacent convoluted rollers is directly under the optical system. These gating pulses control operation of the circuitry of the grading apparatus and the ejection apparatus. With this arrangement, the rollers are in effect blanked out of the field of view of the optical system and the grading system can "see" only articles and objects in the pockets between rollers.

Abstract: A switching circuit for a static inverter employing a plurality of parallel switching stages for switching a d.c. voltage to produce an a.c. output. Novel driver circuit for all switching stages of a group also serves as switching means for first switching stage of the group.

Abstract: A push-push type of switching apparatus having a push rod movable in a slideway on one face of a flat mounting bracket. A snap switch is mounted on the opposite face of the bracket. A pivotable actuating lever extends transversely through the bracket. The lever has one paddle portion in the slideway in the path of the push rod and a spaced second paddle positioned over the actuator of the snap switch. Depression of the push rod displaces the first paddle out of the path of the rod and pivots the lever. Pivoting of the lever causes the second paddle to depress the actuator button of the snap switch.

Abstract: A monitoring circuit to detect an open circuit in the ground conductor of an electrical system. The circuit also senses a high inpedance and leakage current in the ground conductor. Additionally, the circuit protects against reversal of the high and neutral input supply conductors. The circuit includes a delayed latching circuit which prevents reconnection of a device to be protected.BACKGROUND OF THE INVENTIONIn many diverse situations involving the use of electrical equipment it is desired to know that the a.c. lines from the source are properly connected and that the ground line is free of faults. This is particularly true where humans will be in contact with the frames and housings of apparatus containing electrical equipment. At the present time it is very desirable, and in some instances mandatory, that ground monitoring devices be used on mining apparatus, and on electrical or electronic medical apparatus, for example.

Abstract: A produce grader that includes first and second signal paths for producing first and second signals corresponding to respective detected characteristics of an article of produce being graded. Each signal path includes chopper means for converting d.c. signals to a.c. signals, a.c. amplifier means, and means including synchronous detector means for reconverting amplified a.c. signals to d.c. signals. The reconverted signals are compared and/or evaluated to establish a basis for grading. Means are provided for adjusting the duty cycle of the gating signal controlling at least one synchronous detector thereby adjusting the gain of the corresponding signal path and adjusting the calibration of the grader.

Abstract: A duplex receptacle model GFCI device having preformed bus conductors of generally U-shaped configuration disposed on edge and one nested within the other preformed clip receptacles and support means for circuit breaker contacts are integral with the preformed bus conductors and form respective unitary conductors which are placed edgewise into slots molded into the case of the device.

Abstract: An improper or undesired second ground connection on the load side of the neutral conductor of an electrical supply system is detected by coupling an oscillator to the neutral conductor and to least one other conductor of the supply system in a balanced mode. In the absence of said improper or undesired second ground, oscillator signals cancel on the two conductors. When said second ground is present, oscillator current flows therethrough and the impedance change in the grounded neutral conductor is reflected back to the oscillator tank circuit to change the output signal of the oscillator. Change in output signal is detected and actuates circuit breaker to disconnect the supply system.