Abstract: A fast turn-on FET circuit is provided by a constant current source and fast turn-on capacitor combination in the gate circuit of the FET. At turn-on, a bypass capacitor momentarily short-circuits a control resistor in the current source such that a momentarily higher current is supplied by the current source to the FET gate until the capacitor is charged, whereafter constant current as controlled by the resistor is supplid to the FET gate circuitry to maintain conduction.

Abstract: A power thyristor is provided with a pair of antiseries back to back diode junctions forming an open base transistor thermally coupled to the thyristor and electrically connected between the thyristor gate and cathode. The diode junctions shunt gate current above a given sensed temperature of the power thyristor, for protecting the latter by preventing turn-on thereof. The diode junctions have nonsymmetrical leakage current characteristics to insure protective shunting of forward gate drive in one direction but blocking leakage in the other direction to prevent draining a reverse charged phasing capacitor. The latter is thus charged beginning from the same starting reference point in each cycle whereby to insure accurate phase control in an AC gating system.

Abstract: A simple rectified AC frequency conversion technique is provided by chopping positively and negatively rectified AC signals by alternatively switching therebetween to yield a switched output waveform of given frequency without capacitive filtering to DC. The direct AC switching provides an irregular chopped sinusoid output waveform.

Abstract: A control for establishing a rotating field in a single phase AC induction motor (10) having a rotatable output and first (12) and second (14) sets of mechanically displaced windings which are energized alternately and cyclically by a single phase AC input for establishing the rotating field to effect rotation of the output. The control includes a single phase AC input, first and second solid state switch means, 18, 20, for interconnecting the first and second sets of windings, respectively, of the motor with the AC input. The first and second switch means when conductive apply energy from the input to the first and second sets of windings, respectively, and when non-conductive prevent the application of energy from the input to the first and second set of windings, respectively.

Abstract: An AC transistor switch is provided with simple, accurate and fast overcurrent protection circuitry. A pair of transistors are connected in anti-series across an AC load line, and each transistor has an anti-parallel diode therearound conducting current in the alternate half cycles. Comparator means senses current flow through the diodes and is responsive to given threshold overload current to turn off the transistors. Voltage sensing means is referenced to a common point between the series connected transistors and senses the voltage at each main terminal relative to the common point to thus sense the voltage drop from the common point across each diode to its respective main terminal for sensing current flow through the respective diode.

Abstract: A gate turn-off device is disclosed having a load current carrying power transistor regeneratively collector-base coupled with another transistor, and includes a third, shunting transistor providing high gain turn-off. The device is turned ON by signal current of one polarity applied to the base of the power transistor driving the latter into conduction to carry load current, and the device remains ON upon removal of the signal due to base drive supplied by the collector of the other transistor in the regenerative loop. A third transistor is connected to one of the collector-base junctions to shuntingly break the regenerative loop when the third transistor is biased into conduction, thus providing higher gain turn-off. A single ON-OFF control terminal is disclosed, as well as separate ON and OFF control terminals.

Abstract: An oscillating stack receiving table carries thereon a pair of cooperating chain driven ejector assemblies which function in their "at rest" position as gates to stabilize the stack of articles during rotation of the table and which are operable to sweep across the table when the latter is "at rest" to eject the stack of articles from the table onto associated take-away conveyor apparatus.

Abstract: A multi-position selector switch of the sliding bridging contact type having a molded plastic base and a metal cover closing the open top of the base and also serving to pivot the operating lever. A plurality of similar one-piece stationary contact-terminals are inserted through holes in the bottom of the base and are held in place by a plastic liner that is dropped in to hug the walls of the base and is clamped down by the cover. The stationary contact-terminals have pairs of wings recessed in the bottom of the base whereby they are held in place by the plastic liner. A movable bridging contact is spring-biased on a reciprocal actuator block that is detented to the cover. The inner end of the operating lever extends into a slot in the actuator block whereby the latter is moved over the stationary contacts from one detent to another. The switch parts are designed for simplicity and east of manufacture and automated assembly.