Abstract: In a combination switch having both rotary and pushbutton momentary switches, a method for determining which switch has been selected by a user. The method also includes distinguishing between the selection of a rotary switch from a pushbutton switch.

Abstract: A high voltage switching matrix for selectively connecting a plurality of different voltage/current sources or inputs with a plurality of different outputs includes a common or shared relay for each of the voltage/current sources at the voltage/current source inputs rather than at the output ports.

Abstract: A method for providing a current path during switching transitions of a switching circuit while limiting the short circuit current. In one embodiment, a switching circuit includes a passive break-before-make element in series with two switches. An alternate embodiment includes a make-before-break element in parallel with the switches. The passive break-before-make element, or make-before-break element, provides a high impedance in a short term and a low impedance in a long term. The switching circuit may be coupled to a load through a low pass filter. In one embodiment, the switching circuit is used in a switching audio amplifier circuit, where correction of nonlinearities incorporates analog feedback to modify the duty ratio of a digitally generated switching signal in the analog domain.

Abstract: An input power stabilizing circuit, adapted to be disposed between a DC power source and a load to which DC power from the source is to be supplied. Voltage on a capacitor in the input power stabilizing circuit is prevented as much as possible from causing reverse current to flow when the DC power source develops a short circuit momentarily. A current detecting unit detects reverse current from the capacitor in an input power supply line, and a current interrupting unit interrupts a current line connecting the load with the DC power source. When reverse current flow is detected, the current line is interrupted by the current detecting unit and the current interrupting unit. The reverse current from the capacitor is held to a minimum value in the input power stabilizing circuit.

Abstract: An electromechanical switching device ensures automatic selected polarity interconnection between terminals of two power sources. A double pole double throw (DPDT) switch has three pairs of contacts. A first pair of leads connect to two pairs of contacts in a manner that reverses polarity when switched, while a second pair of leads connect to the other pair of contacts. A switch controller employs a plurality of coils in electrical communication with the two pairs of leads. The coils are arranged and configured so that, when the two pairs of leads are connected to the respective power sources, the coils cause an actuator to move the switch automatically into the correct polarity state regardless of the connections of the leads. The invention is described as a battery jumper cable and to automatically connect like terminals of a pair of batteries. The invention encompasses the method of this device.

Abstract: A micro-electro mechanical switch having a restoring force sufficiently large to overcome stiction is described. The switch is provided with a deflectable conductive beam and multiple electrodes coated with an elastically deformable conductive layer. A restoring force which is initially generated by a single spring constant k0 upon the application of a control voltage between the deflectable beam and a control electrode coplanar to the contact electrodes is supplemented by adding to k0 additional spring constants k1, . . . , kn provided by the deformable layers, once the switch nears closure and the layers compress. In another embodiment, deformable, spring-like elements are used in lieu of the deformable layers.

Abstract: A circuit and method are disclosed for monitoring the state of at least one switch. The circuit may include a first circuit, coupled to a switch, for detecting whether the switch is in one of a closed state and an open state and generating a signal having a value based upon the detection. The circuit may further include a second circuit, coupled to the first circuit, for configuring the first circuit to selectively detect the switch switching from a normally open state and to selectively detect the switch switching from a normally closed state.

Abstract: A method of shutting down a pluggable electrical unit in a modular system comprising a base unit and at least one pluggable electrical unit connected via an interface. Each pluggable electrical unit has module electronics and a switch, which is coupled to a mechanical locking of the pluggable electrical unit in the base unit. The electronics is provided with a variable resistor, arranged in a feed line and is communicatively connected to the base unit via switching means. For removal, the pluggable electrical unit to be removed is unlocked and the switch is actuated. Then, communication operations in progress between the base unit and the pluggable electrical unit to be removed are terminated. The communication connection routed via the switching means is disconnected and the module electronics of the pluggable electrical unit to be removed are isolated from the base unit.

Abstract: A switchgear cabinet air conditioning device having at least one cooling device, which has a cooling device control and a connected operating device. A simple operability is achieved because the operating device has a server which is assigned to the cooling device control, and has a network connection as well as at least one personal computer, which is connected via the network connection and via a universally accessible network and has an assigned web browser, by which the data retrieved from the server can be visually displayed.

Abstract: A pluggable electrical unit with module electronics has a bus access unit for electrical connection of the pluggable unit to an electrical base unit. The base unit comprises a power supply, a signal processing means and signal lines for identification, control lines, address lines and data lines, which are connected in the manner of a bus to a plurality of contact devices. The bus access unit has a variable resistor and switches for isolation. The variable resistor and the switches for isolating signal lines for identification, control lines address lines and data lines in the pluggable electrical unit are linked to one another in a causal chain.

Abstract: A self-normalling jack with an electronically controlled normal circuit or relay comprising a pair of receptacles having a sensing means for sensing the insertion of a plug, the sensing means in communication with an electronic normalling switch or relay, the electronic normalling switch or relay in communication with a paired receptacle such that the electronic normalling switch or relay is located between the source terminal and the upper jack and between the lower jack and the destination terminal. The electronically controlled normalling circuit or relay also connects the source to the destination when no patch cord is inserted into either the upper or lower jack receptacle. When the patch cord is inserted into the upper jack, the source signal is connected to the patch plug. When the patch cord is inserted into the lower jack, the destination signal is connected to the patch plug. Inserting a cord into either jack receptacle disconnects the source from the destination.

Abstract: A self-normalling jack with a magnetically controlled normal circuit, switch or relay comprising a pair of receptacles having a sensing means for sensing the insertion of a plug, the sensing means in communication with an electronic normalling circuit, switch or relay, the electronic normalling circuit, switch or relay in communication with a paired receptacle such that the electronic normalling circuit, switch or relay is located between the source terminal and the source jack and between the destination jack and the destination terminal. The sensing means being the interruption or non-interruption of the magnetic field by the presence or absence of a patch cord in the jack respectively.

Abstract: A self-normalling jack with an electronically controlled normal circuit or relay comprising a pair of receptacles having a sensing means for sensing the insertion of a plug, the sensing means in communication with an electronic normalling switch or relay, the electronic normalling switch or relay in communication with a paired receptacle such that the electronic normalling switch or relay is located between the source terminal and the upper jack and between the lower jack and the destination terminal. The electronically controlled normalling circuit or relay also connects the source to the destination when no patch cord is inserted into either the upper or lower jack receptacle. When the patch cord is inserted into the upper jack, the source signal is connected to the patch plug. When the patch cord is inserted into the lower jack, the destination signal is connected to the patch plug. Inserting a cord into either jack receptacle disconnects the source from the destination.

Abstract: This invention includes an electronic accessory having a single button that actuates all of its control features. In one embodiment, the accessory is a MP3 player wherein songs are stored on a multimedia card. Once the card has been loaded an inserted, the MP3 player is coupled to an energy source. In a preferred embodiment, the energy source is preferably a cellular telephone. After coupling, all of the functions of the MP3 player are controlled with a single button. In a preferred embodiment, power is actuated by pushing the button for one second. Volume is adjusted by toggling the button laterally. Tracks are selected by pushing the button quickly while power is applied. Power is turned off by depressing the button for two seconds or more.

Abstract: A circuit configuration is used for off-load switching. The circuit configuration can be used as a component in a switch mode power supply, a clocked supply, a voltage regulator, and a lamp switch, wherein the circuit configuration is embodied as an IGBT, especially a field stop IGBT or alternately and additionally as a PT IGBT. A method for using the circuit configuration include three operating modes: in a first operating mode, power for a load is modulated by pulse modulation; in a second operating mode, the power is modulated by changing a switching-on time; and, in a third operating mode, both are implemented.

Abstract: A method and device that controls one or more apparatus in relation to the expected time of sunrise and sunset at the location of the apparatus. The operator enters a geographic location identifier, such as a zip code or telephone area code, and the controller computes the expected time of sunrise and sunset at the corresponding geographic location. The controller is configured to translate the entered geographic location code into the offset times, based upon the latitude and longitude of the location. The controller is able to either directly retrieve stored time offsets or it retrieves the latitude and longitude that corresponds to the entered geographic location code and determines the time offset from that latitude and longitude.

Abstract: A DC power source unit includes a main unit that generates DC voltage, and an output cable. The output cable is connected, either integrally or detachably, at one end to the output of the main unit and another end to an adapter plug. The adapter plug is electrically connected to an electrically powered tool, such as an electrical drill. An output voltage switching unit switches the level of voltage supplied by the main unit to the electrically powered tool, to a level that matches the rated voltage of the electrically powered tool that corresponds to the fitting portion of the adapter plug.

Abstract: The present invention relates to a high-reliability vehicle mounted device control apparatus capable of making a decision about functions of switch units with a simple structure and at a high processing speed and a low cost. Each of the switch units comprises a circuit substrate having a required circuit pattern formed to include a plurality of pairs of short-circuiting possible land portions, and a switch mounted on the circuit substrate so that any one of the plurality of pairs of land portions are short-circuited selectively to set a switching function inherent to that switch unit. Any one selected from the switch units is mounted in one of the unit mounting sections, and the switch of that switch unit is turned on. A switch unit decision section constituting a control section detects the land portions short-circuited to automatically make a decision about the kind of a switching function of the mounted switch unit.

Abstract: A smart card interface device which can be installed in an expansion slot of a handheld device comprises: a host interface unit for connecting with I/O ports included in the expansion slot of the handheld device so as to receive/send serial communication data signals and clock signals from/to said I/O ports; a first smart card connector provided at a surface of said smart card interface device, for electrically connecting with a smart card of the first type; a first smart card interface unit for detecting whether a smart card of the first type has been connected to said first smart card connector and for driving the smart card of the first type being connected; a protocol implementation unit for controlling each component of said smart card interface device so as to implement communication protocols between said smart card interface device and said handheld device as well as between said smart card interface device and said smart card of the first type.

Abstract: Disclosed is structure and method for supplying and cutting off power to a removable card component of an electrical device, without interfering with supply of power to other components of the device (including other card components), so that the single card component can be serviced (removed/replaced/added) without interfering with supply of electrical power to other components of the electrical device. The structure includes a slider member on the frame of the device, which slides on the frame between first and second positions on the frame, and a switch actuated by the slider member.

Abstract: Control device for a multiphase electric motor (M) comprising firstly two two-directional static switches (IS1, IS2) each associated with a terminal of a shunt contactor (S) installed in parallel, these switches (IS1, IS2, S) being controlled by a control circuit (C) controlling progressive operation of the motor, characterized in that the shunt contactor (S) is of the four-pole type and is fitted with solid connection parts (6, 7) each connecting two terminals of the said contactor, these connection parts (6, 7) being connected in pairs (L1, L3) to the terminals of the static switches (IS1, IS2) such that each (IS1 or IS2) is connected to two terminals.

Abstract: A fail-safe circuit (10) comprises a storage battery (11) for electrical charges as well as a first charge path (12) which optionally connects the storage battery (11) to a first potential (UL). A second charge path (14) and a third charge path (15) optionally connect the storage battery (11) with a second or third potential (UE1, UE2). The first and second switching devices (16, 17), which operate as function of the first and second switching events (TA, TB), each comprise a first and second switching contact (A1, B1) in the first charge path (12) and a second switching contact (A2, B2) in the second and third charge path (14, 15). The actuation coils (LC, LD) of the third and fourth switching devices (18, 19) are in the second and third charge path (14, 15) and each have a first switching contact (C1, D1) in the first charging path (12) and a second contact (C2, C2', D2, D2').

Abstract: A portable communication device with battery conservation capability is capable of sensing (223) its power source and suppressing a battery conservation circuit depending on an actual voltage determined (225) from an analog-to-digital converter. Two or more voltage ranges are defined (227) such that battery conservation is disabled when an external power source is operated in one of the predetermined voltage ranges.

Abstract: A power source adaptor employing a small switch to securely and positively turn on and off the power source, and which can be detachably connected to an electrical apparatus. To avoid the cost and excessive size associated with prior art power source adaptors, the adaptor can include an auxiliary switch element provided for the control section of an electrical switching element to selectively start and stop a switching operation. A switch operating button on an adaptor housing operates the auxiliary switch element. An insulated coupling bar is also provided through which the switch operating button is mechanically coupled to the power on/off operating button on the apparatus body.

Abstract: An electrical switching device such as a motor starter includes separable contacts; a coil for operating the separable contacts; two light emitting diode indicators having a plurality of states; a pushbutton switch; and a control circuit responsive to the pushbutton switch employing a plurality of parameters for controlling operation of the coil and the indicators, with the control circuit having a setup mode and including a microcomputer for detecting actuation of the pushbutton switch to enter the setup mode, indicating a first one of the states on the indicators corresponding to a first one of the parameters, and detecting de-actuation of the pushbutton switch to indicate a value of the first parameter on the indicators.

Abstract: There is described method and apparatus to obtain synchronized switching of switchgear. A superposition of forces is used wherein the moving contacts of switchgear driven by a conventional operating mechanism has a secondary force, either opposing or aiding, superimposed upon the mechanism force under predetermined conditions to incrementally either slow down or speed up the moving contact. The computed secondary force is applied by a small servo-motor attached to the moving contact shaft. The energy of the secondary force is derived from a real time comparison of the measured position of the moving contact with its preprogrammed position in ROM at each predetermined point on the voltage or current waveform. From this comparison the required pulse energy is calculated and fed to the servo-motor which translates into the secondary force of appropriate duration thereby making the necessary incremental velocity correction.

Abstract: Disclosed is a low current binary input subsystem for providing a binary input signal to a data acquisition system. The binary input subsystem monitors the open/close state of a field contact and provides galvanic isolation of noisy field contacts, high noise immunity, a steady state current of approximately 1.2 milliamps resulting in power dissipation of approximately 0.25 watts for a 125 VDC input, and a momentary high current pulse of approximately 150 milliamps for a duration of approximately 4 milliseconds during field contact closure to aid in cleaning of oxides from the field contact.

Abstract: Connection of batteries to the DC bus lines across which capacitors are connected in power systems, such as uninterruptible power systems, is carried out using an auxiliary switch which is controlled to connect the batteries to a DC bus line through a precharge resistor momentarily before connection is made through a main connector. The preconnection of the batteries through the precharge resistor provides a controlled rate of charge of the capacitors before closing of the main connector to thereby avoid excessive surge currents. When the main connector is opened, as when the power system is prepared for transportation or long term storage, the auxiliary switch interrupts the current path from the battery through the precharge resistor and provides a current path from the DC bus line through a discharge resistor to ground to bleed down the charge on the capacitors to a desired level within a selected period of time.

Abstract: A frequency slider circuit for reducing power dissipation in the form of switching losses in a switching device when the switching device is near its desired maximum temperature limit is disclosed herein. The switching device controls an electric load, such as a motor. The frequency slider circuit samples a current of the switching device. The frequency slider circuit then uses a current transducer to convert the current to a signal level. The signal level is then processed by a model of the thermal response of the switching device. The output of the thermal model is compared to a reference signal, and if the output of the thermal model is greater than the reference signal, the switching frequency of the switching device will be lowered gradually to keep the power generated during the switching periods to be below a predetermined value. A minimum frequency clamping circuit is included to ensure that the switching frequency never drops below a minimum value, to ensure stable operation of the switching device.

Abstract: A device for preventing welding of the switch contacts of a heavy duty electromechanical relay comprises means (15, 16 and 17) adapted in use for monitoring the voltage supply to the relay coil (2) and detecting low voltage excursions therein. A counter (14) counts the number of low voltage excursions in the voltage supply to the relay coil (2) and an electronic switch (12) disconnects the voltage supply to the relay (2) if the number of low voltage excursions counted exceeds a predetermined number.

Abstract: In a multicircuit control apparatus (10) including a mechanical main contact (125) and plural semiconductor switching devices such as triacs (13a, --, 13d) each connected in series to the main contact, the main contact is closed by a control circuit 15 prior turning-on of any of the semiconductor switching devices and is also opened by the control circuit 15 after completion of turning-off of all the semiconductor devices.

Abstract: A power source system failing to become operable when only a primary A.C. power source is turned on, and made operable by turning on not only the primary A.C. power source but also a secondary power source is disclosed, in which initial-state-of-secondary-source setting means is previously set so that the initial state of the secondary power source at a time when the primary A.C. power source is turned on, is a desired one of an ON-state and an OFF-state, a system control part reads out the state of the initial-state-of-secondary-source setting means immediately after the primary A.C. power source has been turned on, and an ON-OFF control is performed for an ON/OFF switching circuit in accordance with the read-out state, to make the initial state of the secondary power source equal to the desired state. Thus, in a case where a controlled apparatus is required to become operable as soon as the primary A.C.

Abstract: False ac signals produced by a noise suppression capacitor across a switch applying a switched ac line voltage signal to a logic input of a microprocessor in an electrical apparatus such as, for example, a contactor or circuit breaker, are phase shifted with respect to a true ac input by inserting two series resistors, and a diode shunting one resistor, between the switch and the logic input. This creates a larger window in which to discriminate between the zero crossings of the true and false ac signals.

Abstract: A synchronizing circuit includes two switches for synchronizing the feeding of documents of a document feeder to the insert path of an insertion machine which is operative in accordance with a predetermined machine cycle to establish a given level of vacuum in a vacuum lines. The first switch closes in response to a given level of vacuum in the vacuum line and a rotary magnet driven by the insertion machine causes the second switch to close and then open at given machine cycles. The second switch and the first switch are in series with the document feeder; and, the second switch is operative to be closed and be held closed by the rotary magnet so that the document feeder is operative only upon the occurrence of both a given level of vacuum in the vacuum line and the predetermined proximity of the rotary magnet to the second switch.

Abstract: A precharged capacitor connected in parallel with the contacts of an open switch discharges through the switch upon closure. Oxides on the switch contacts are broken through upon closure of the switch to produce a good electrical connection. The capacitor provides sufficient voltage and transient current to clean the switch contacts. A microprocessor having signals of only 5 volts can interrogate a plurality of such switches by multiplexing some semiconductor switching circuits that energize the interrogated switches and by synchronously multiplexing some microprocessor input circuits. The microprocessor's input circuits therefore receive signals indicating the status of each switch in turn.

Abstract: An electronic device has an operating section having a plurality of input keys. The operating section is detachably connected to a body of the device in such a manner that the contacts of the operating section are electrically connected to the contacts of the body when the operating section is connected to the body. The body includes a connection detecting section for detecting the connection of the operating section to the body to output a connection detection signal; and a control section for making the connection of the contacts of the body and the contacts of the operating section effective a predetermined period of time after provision of the connection detection signal.

Abstract: The tendency of a motor-driven actuator driving against a dynamic (non-frictional) load to return upon reaching the limit switch sufficiently to again close the limit switch and create a persistent oscillation at the limit position can be prevented by placing a positive temperature coefficient thermistor across the limit switch involved. Such loads typically arise in actuators having spring-driven return capability, and can also arise when positioning air dampers and other loads where the actuator force is opposed by a spring or gravity.

Abstract: A hybrid relay comprising a mechanical relay provided with mechanical contact unit adapted to be actuated by an electromagnet, an electronic relay consisting of a semiconductor device, and a drive switch for supplying a drive current to the electromagnet, wherein the mechanical contact unit comprises: a first contact mechanism for controlling a load current of the hybrid relay; and a second contact mechanism for controlling a control current for a control gate of the semiconductor device; a contact point gap of the first contact mechanism being larger than that of the second contact mechanism. Thus, it is ensured that the first contact mechanism is engaged after the second contact mechanism and is disengaged before the second contact mechanism. Preferably, the mechanical contact unit further comprises a third contact mechanism, for controlling the leak current of the semiconductor device, which may be provided with a delay mechanism for delaying the returning action thereof.

Abstract: A device for connecting and disconnecting a board in a hot state includes a board and a mother-board. The board has mounted thereon dynamic elements through which a low electric current flows during a clock signal disabled state, and a clock signal enable or disable circuit. When a board must be connected or disconnected in the hot state due to a fault therein, the clock circuit in the board is set to the disabled state. The board is connected or disconnected while a low current flows therethrough, after a new board is connected, the clock signal disabled state is released. Thus a connector connecting the board with the mother-board cannot be damaged by a flow of a large electric current during a connection or disconnection of the boards.

Abstract: A computer bus structure is provided which permits replacement of removable modules during operation of a computer wherein means are provided to precharge signal output lines to within a predetermined range prior to the usage of the signal output lines to carry signals, and further, wherein means are provided to minimize arcing to pins designed to carry the power and signals of a connector. In a specific embodiment, pin length, i.e., separation between male and female components of the connector, are subdivided into long pin length and short pin length. Ground connections and power connections for each voltage level are assigned to the long pin lengths. Signal connections and a second power connection for each voltage level is assigned to the short pin lengths.

Abstract: Such electronic control systems contain safety circuits for device components endangered by excessive currents or excessive voltages, which are constructed only for a pulse operation and not for higher relative switch-on times.In order to shield the effectors (users) already in the pre-stage against undesirable high currents or, respectively, voltages, such that a punch through of these destroying voltages or, respectively, currents can be excluded for practical purposes, it is disclosed that an effector (1) is controllable in operating condition and simultaneously a reference voltage (R1/R2) can be switched on within the permissible tolerance region where, upon the exceeding of the tolerance region, the effector (1) can be switched off.

Abstract: A switching circuit for supplying electric power to a load from a power source includes a first relay device having a first switch and a semiconductor switching element connected in series with the first switch, power source and load. A second relay device is provided which is defined by a second switch connected parallelly to the semiconductor switching element and an actuating switch for enabling and disabling the semiconductor switching element. The second relay device is so arranged as to effect the make of the actuating switch and second switch in said order and to effect the break of the same in the opposite order. A delay circuit is provided for controlling the first and second relay devices such that when supplying a current to the load, the first and second relay devices are turned on in said order so that the first switch, the actuating switch and the second switch are turned on in said order.

Abstract: The present invention is capable of applying a voltage across the contacts of a switch or connector in an audio system, the voltage being of sufficient level to provide a sufficiently high current to break down an insulating layer which has built up in the contacts thereof, improving the sound quality of the system. The invention may be an independent unit or may be incorporated in the overall audio system as an integral part thereof.

Abstract: An electromagnetic contactor without arc generation wherein the silver contacts are omitted by providing contact portions between the fixed terminals and the movable piece to separate the semi-conductor completely from the power supply under open-circuit condition. In the contactor, the cylindrical holes are provided in each silver contact portion of the fixed terminals, the circumference of the holes being rounded to conform to the curvature radius of the contact portions which project from the conductive movable piece. The conductive pins wound by the coil springs are supported by the insulating plates to be isolated from the fixed terminals and also electrically connected via the subsidiary terminals to one terminal and a gate of a triac, respectively.

Abstract: Re-strike in the circuit breaker of a capacitive load applied across an AC voltage power supply is reduced or avoided by connecting across the capacitor bank a tuned discharge circuit. The tuned discharge circuit includes a transformer with a primary connected in parallel with the capacitor bank and a secondary which can be shorted through a switch. The leakage reactance of the transformer is equated to the capacitive reactance of the capacitor bank so that the tuned circuit discharges the capacitor voltage in phase with the supply voltage. The discharge takes place through a number of cycles thus gradually increasing the voltage across the breaker gap. The switch in the secondary preferably comprises an anti-parallel pair of thyristors fired by a circuit responsive to current zero in the capacitive circuit detected over a delay period to avoid firing at normal zero crossing current.

Abstract: An electrical motor contactor or controller is taught in which control signals from remotely located pushbuttons are supplied to the logic portion of the controller for the purpose of initiating or stopping a predetermined contactor or controller actions. The controller or contactor is of a universal nature adapted for the acceptance of relatively high voltage AC control signals or relatively low voltage DC control levels. For instance, a 120-volt AC signal may be provided or a 5-volt DC level may be provided. Because an AC signal may be provided to the controller, capacitive filter elements are utilized in the control circuit for filtering transients or AC components above a predetermined frequency which may be 60 Hz for example. Furthermore, voltage regulator elements within the control circuit and the microprocessor input terminals within the control circuit represent relatively high impedance in the discharge path for the aforementioned capacitors.

Abstract: The oral machine controller is an apparatus for controlling operations of a machine by jaw and tongue movement of an operator. Upper and lower dentition grips include thermoplastic members which are conformed to tooth shape to cling thereto. A lightweight control unit in a housing includes a straight potentiometer which generates a controllably variable voltage signal to control a speed or intensity function of the machine. One dentition grip is attached to the control unit housing by a first control arm and the other to a second control arm which is attached to a moveable contact on the potentiometer for changing its position and controlling the speed or intensity function of the machine. A tongue-actuated microswitch is provided for additional control of machine functions.

Abstract: A multi-function circuit controller provides auxiliary control functions for an existing single-pole, single-throw toggle switch by counting the number of changes of state of the switch that occur within predesignated delay periods from one state change to the next. An encoder responsive to a sequencer counter develops control functions such as dimming and timing functions which attenuate the power delivered to the load and regulate the on-off time of the load. The invention may be used in conjunction with a household lighting circuit to provide these functions for an existing wall-mounted switch, thereby providing dimmer and programmable timing for the lighting normally controlled by the switch.

Abstract: A switch system for overhead electric extension cords for remotely controlling overhead-mounted electrical appliances, such as fans. A drop cord includes an upper end having electrical fittings connectable to an overhead power supply extension cord and the electric user cord, and the lower end of the drop cord includes a switch at an accessible level from the floor. The drop cord switch controls the circuit between the power supply and user cords, and a strain relief cable anchored overhead supports the weight of the switch.

Abstract: A DC power switching circuit connecting a load to a DC power source while suppressing arcing across a relay in the network. A normally open relay has its energizing coil connected to the control input of the circuit, the opposite end of the coil being connected to the gate of a silicon controlled rectifier. The SCR has its principal current conducting path connected between the load and the DC power source, for conducting current between the load and the power source during a first delay interval, thereby reducing the potential difference between the contacts of the relay so as to prevent its arcing during the closure of the contacts. An FET device has its principal current conducting path connected between the load and the DC power source and has its gate connected to a timer.