Abstract: A constant current circuit including a silicon controlled rectifier connected to transmit current flow from an ac supply to a load. A sensor circuit provides a load signal having a level dependent upon the current flow through the load and a reference circuit provides a reference signal having a predetermined given level. Receiving the load and reference signals is a comparator with an output connected to an SCR firing control network that furnishes firing signals to a gate of the silicon controlled rectifier. The output from the comparator varies the firing signal produced by a phase shift network in response to a reference signal level greater than the level of the load signal and retards the phase of the firing signal in response to a load signal level greater than the given reference level.

Abstract: A circuit for sensing the current applied to a load in power supplies, inverters, and other power conversion equipment and similar systems wherein the voltage between the center tap of the transformer secondary winding and the junction of two resistors connected across the secondary winding in series is sensed. The control circuit for the electronic system adjusts the overall system operation to obtain the desired volt-ampere output in response to this voltage level.

Abstract: A controllable rectifier circuit which may be used in a power supply selectively produces a half-wave or a full-wave rectified signal. The rectifier circuit includes a pair of input terminals for receiving an AC signal and a bridge rectifier coupled to the input terminals and including a pair of output terminals across which a rectified AC signal is produced. The bridge rectifier comprises a first current path including a switchable rectifier for conducting positive half cycles of the AC signal and a second current path including a switchable rectifier for conducting negative half cycles of the AC signal. A pulse generator is supplied with reduced amplitude versions of the positive and negative half cycles of the AC signal, in sequence, to produce an output pulse when the reduced amplitude of the half cycle supplied thereto is less than a predetermined level.

Abstract: A converter in one embodiment including six solid-state switches arranged as a three-phase bridge circuit operable in a first mode for inverting the DC voltage from a battery into a plural phase AC output voltage, and operable in a second mode as a single-phase bridge rectifier for controllably rectifying single-phase AC line voltage into a DC voltage. An AC relay in its de-energized state has switch contacts for connecting the three-phase AC output voltage to three output terminals, and the battery voltage across the bridge circuit for inversion. A single-phase AC line voltage is connected to the converter for energizing the relay, for disconnecting the bridge from the output terminals, for connecting the AC line voltage to the bridge for rectification thereof, and for reversing the connections of the battery to the bridge. A microprocessor is preprogrammed for controlling the operation of the bridge circuit for either the inversion or rectification modes of operation.

Abstract: A rectifier and preregulator circuit using a first silicon controlled rectifier (SCR) to rectify AC voltage and apply the rectified voltage across a capacitor which is used as a storage device. The circuit also includes a transistor, zener diode and a second (SCR) in a switching arrangement for turning on the first SCR and for turning off the transistor and zener diode when a minimum voltage is reached so as to minimize dissipation of electrical power in the circuit. A second zener diode and a third SCR are used in a switching arrangement to control the maximum rectified voltage from the circuit.

Abstract: A circuit comprising first and second rectifiers for supplying rectified current or voltage to a storage capacitor located at the output of the circuit. The circuit includes a control circuit operatively coupled between the output and the silicon controlled rectifiers to insure that alternate ones of the silicon controlled rectifiers will supply the rectified current or voltage to the storage capacitor as needed.

Abstract: A controller for selectively energizing actuating coils of rappers of an electrostatic precipitator assembly to impart motion to a portion of the precipitator assembly and remove accumulated material therefrom. The controller intermittently supplies a d.c. potential to a rapper supply bus common to a plurality of rappers of the electrostatic precipitator assembly for time periods each of a predetermined duration. Switching means responsive to the d.c. potential selectively connect an actuating coil of at least one rapper of the plurality of rappers to the rapper supply bus during each of the time periods to energize the actuating coil of at least one rapper with the d.c. potential. In the preferred embodiment, the d.c. potential is supplied by an SCR controlled rectifying means and the switching means each comprise an SCR. Means are provided for selectively varying a time interval between the time periods during which the d.c.

Abstract: A power-supply device for a working machine such as a spark-erosion machine, arc welding machine or the like substantially eliminates the break-down or misoperation of thyristers used in the device and wherein the device includes a circuit which comprises a power transformer, a thyrister rectifying circuit, a diode rectifying circuit, and a trigger circuit for triggering the thyrister of the thyrister rectifying circuit.

Abstract: The amplitude of the rectified voltage applied to the filter capacitor of a power supply is varied by selecting different taps in the secondary winding as a function of the output voltage and current so that the supply provides a wide range of operating voltages and currents in a minimum volume and at reduced cost.

Abstract: A power converter system comprises a connection of a plurality of controlled rectifiers and a plurality of uncontrolled rectifiers, or a connection of only a plurality of controlled rectifiers. With an AC power supply as an input, the firing phase of the controlled rectifiers is controlled for conversion into a desired power. The commutating operation of the rectifiers is performed by utilizing the AC power supply. A retardation coil is connected to each of the rectifiers connected in series in the same polarity and making up an arm of the connection. The thus connected retardation coils are magnetically coupled with each other.

Abstract: A circuit for providing firing signals for SCRs, particularly suitable for use where the power waveform is distorted. The firing signals are based on fixed angles of the power signal rather than on a time basis. Ramp signals from a ramp generator are compared with a loop error voltage or reference voltage for providing the SCR firing signals. A voltage controlled oscillator in a phase locked loop generates an undistorted signal used to start the ramp generator. The output of a lowpass filter in the phase locked loop provides a frequency compensating signal for controlling the slope of the ramp signals.

Abstract: A method of triggering a controlled rectifier to ensure that it conducts fully and remains conducting for a required time, comprising supplying to the control electrode of the rectifier a large amplitude pulse with high transductance per unit of time to initiate conducting, and a small amplitude signal to maintain conducting. A circuit for producing such a pulse and signal comprises a pulse generator and a blocking oscillator both controlled by a control generator.