Abstract: A circuit for varying the current to a load and, simultaneously, limiting the output of the load to a predetermined time interval. A timer chip having an RC network receives rectified current from an AC voltage source and responds thereto with a high output, which is used to bias an NPN transistor. The transistor permits the flow of rectified current to a logic triac, thereby triggering the logic triac and enabling current from the AC voltage source to flow to a variable resistor in series connection with a gating/AC timing capacitor, thereby triggering a diac. The diac responds to the controlled current flow from the variable resistor by operating the gate of a power control triac and permitting the desired current flow between the load and the AC voltage source through the power control triac.

Abstract: A switch, that appears the same as an ordinary snap switch, is shown with a positive ON and a positive OFF with a variable control circuit therebetween. The variable control circuit includes a triac gated through a diac to give an infinite control range that depends upon the point at which the triac is triggered. In using the variable control circuit of the switch, a shunt or a bypass is provided for the gate of the triac through a full wave bridge rectifier circuit for a predetermined time interval. The time interval is determined by an RC time constant connected across the bridge. Therefore, for the aforementioned predetermined time interval, essentially a full wave AC voltage is passed through the triac to a load. For motors, this allows the motor to come up to speed prior to subsequently reducing the speed of the motor by the variable control circuit after the predetermined time interval.

Abstract: A light dimmer switch is shown that appears as an ordinary snap switch, but will handle high wattage loads. A controller unit is mounted in a switch box and a remote unit which includes a load switching triac is remotely mounted on a heat sink. Current flowing through the triac to the load is varied by the controller unit. Filtering networks and/or shielding reduce radiated noise along lead lines between the remote unit and the controller unit, plus the filtering prevents noise from being conducted internally along the lead lines. Heat conducted along the lead lines from the remote unit is reduced to more than acceptable levels by connecting the lead lines through a terminal to a thin electrically insulating, thermally conductive strip. In turn, the insulating strip is fixed to the heat sink to transmit heat received from the lead lines to the heat sink.

Abstract: A motor drive system for direct current motors and other similar loads in which the power factor presented to the line by the system remains close to unity for all operating conditions (e.g., all motor speeds). This is accomplished by rectifying an alternating current input voltage and thereafter chopping it to vary power input to the load. An important feature of the invention is the use of a choke at the output of the rectifier of sufficient size to insure that current pulses flowing from the rectifier will be continuous (i.e., will not drop to the zero voltage level) during the sequential ON periods of the rectifier elements.

Abstract: A three-way light dimmer switch is shown wherein the brightness of a lamp or lamps is controlled by independent light dimmer switches with each dimmer switch having its own light dimmer circuit. Each of the light dimmer switches is vertically actuated with one end of the vertical movement turning the lamp or lamps ON, and the other end of the vertical movement turning the lamp or lamps OFF. Between the limits of vertical movement, either of the light dimmer switches may vary the voltage potential received by the lamp to thereby adjust the brightness of the lamp.

Abstract: A mounting assembly for press-pack semiconductive controlled rectifiers wherein the rectifiers are all thermally connected to the same heat sink using an insulating medium, the rectifiers being electrically interconnected using common bus bars as required to provide a desired alternating current or direct current connection. A common spring arrangement is used to apply appropriate pressure to at least two semiconductors at once to hold them in contact with their associated bus bars. At least one of the interconnecting bus bars for the rectifiers is formed of a malleable conducting medium, such as copper, formed and used in a manner to provide load equalizing and surface alignment such that the spring can transmit uniform pressure to the heat sink and the semiconductive controlled rectifiers.

Abstract: A battery charger is provided for industrial storage batteries which includes both digital and analog control circuits for controlling the charging voltage to maintain a charging cycle in which the current is initially held to a maximum value until the cell voltage rises to a preset level, after which the cell voltage is maintained constant at this level until a preset minimum current is reached, and the minimum current is then maintained for a fixed period of time. The charger requires no adjustments for ampere-hour rating or for number of cells in the battery, and is capable of charging batteries of any ampere-hour rating over a wide range, without any adjustment.

Abstract: A pivoted power controller in its limit positions engages a switch operating element to shunt or open a power control circuit through switch contacts mounted on a circuit board. A resistive element mounted in the same circuit board is engaged by a wiper on the controller during travel between its limit positions to vary the power supplied to a load. The resistance of the resistive element may be adjustably varied by a trimmer mounted on the circuit board adjacent one end of the resistive element.

Abstract: Conductive and resistive tracks mounted on a circuit board are slidingly engaged by a bridging contact carried by the actuator arm of a controller that is operative to open or close switch contacts at the limit positions of its travel. The controller is pivotally supported in a non-conductive box within which the circuit board is releasably positioned. A manual control arm projects from the controller through a slot formed in a mounting plate covering the open end of the box.