Abstract: An electronic control for gas furnaces controls a two speed main blower fan and an induction draft fan based on 24 volt input signals from a room thermostat, a high limit and an ignition control including a gas valve. The input signals are coupled to input ports of a microprocessor through current limiting resistors and to AC ground through pull down resistors. AC ground is also connected to the IRQ port of the microprocessor. Output ports of the microprocessor are connected to a relay driver which in turn is connected to relays for energizing and de-energizing the fans. The control calibrates itself on a continuing periodic basis to read the AC inputs synchronously at the peak of their wave and can switch the relays asynchronously based on the Real Time Clock of the microprocessor or can be switched synchronously by providing a selected delay so that contact engagement and disengagement occurs at or near the zero crossing of the AC line voltage wave form.

Abstract: An apparatus interrupts a circuit at a predetermined time. The circuit includes a load and a source of time-varying current. The apparatus includes a relay circuit including a latching relay switch, a first relay coil and a second relay coil, the relay switch switching to engage a first current path when energy is applied to the first relay coil, the relay switch switching to engage a second current path when energy is applied to the second relay coil. The apparatus further includes a switch coupled with the relay means for selectively completing the circuit through one current path of the first current path and the second current path. The apparatus further includes a power supply responsive to the time-varying current for generating a reference voltage, and a timer for measuring a time factor in response to the reference voltage.

Abstract: A solenoid circuit for particular use in a transmission controller measures the instantaneous current through the solenoid coil with the use of a current switch operating in an on mode to cause the current in the coil to increase and an off mode to cause the current in the coil to decrease so that an average current through the coil is established.

Abstract: A time delay switch for use with an electrical load and a source of electrical power, including a multiple-position toggle switch and a user-programmable microchip. The toggle is movable among three positions: an "OFF" position, an "ON" position on one side of the OFF position, and a "TIMER" position on the other side of the OFF position. The toggle is biased from TIMER to OFF so that, whenever it is moved to TIMER, it returns to the central OFF position. When the toggle is moved to TIMER, an electrical signal is sent to the microchip that (1) starts a clock for a preselected period of time and (2) permits electricity to flow through the switch as though the toggle was in the ON position during that time. Alteratively, the microchip can be programmed to start passing current after the preselected period elapses. Thus, the device can be used to turn a light or other electrical load off after a user-determined period of time, or to turn the load on after a preselected time.

Abstract: A circuit for electrically controlled intermittent motion having a time-delay relay and an all-purpose double-pole-double-throw relay for use in conjunction with a gear-head motor having an output shaft, which, upon application to the circuit of a triggering signal either momentary or prolonged for several minutes, rotates approximately 360.degree. and stops.

Abstract: A solenoid drive circuit comprises a timing circuit which activates a voltage control circuit causing a voltage regulator to reduce the voltage output by the driver circuit from a high initial level to a lower holding level sufficient for the solenoid to remain energized. The timing circuit comprises a resistor and capacitor in parallel and the duration of the initial higher voltage output is inversely proportional to the input voltage level. The timing circuit activates a transister in the control circuit changing the equivalent resistance between the adjustment terminal of the voltage regulator and ground thereby causing a reduction in the output voltage.

Abstract: A hybrid switch is provided for switching a sink on and off. The hybrid switch contains a first semiconductor switch with a commutation switch. According to the present invention, a magnetic drive includes a first magnetic coil through which short-circuit current flows. A second semiconductor switch is connected in series with a second magnetic coil that series being connected in parallel to the series connection of the first magnetic coil and the sink. Short circuit flows through the first magnetic coil via the commutation switch which bridges at least the first semiconductor switch.

Abstract: A device including a circuit for energizing a latching solenoid from an AC power source which separates the latching solenoid from the AC power circuit. The device provides for reliable operation of the latching solenoid, and may be separated from the AC power source by several thousand feet of high gauge (lower cost) wire. The device operates on low AC voltage and current making it highly energy efficient.

Abstract: A control system for applying power to a solenoid operated valve in a well completion within a borehole. The control system includes a programmable power supply for selectively applying electric power to a solenoid coil of the valve. The control system operates to apply a higher value of current to the solenoid to open the valve and a second lower value of current to maintain the operation of the solenoid in an open state and also to interrupt all current to the solenoid to close the valve. A timer controls the length of time the higher current value can be applied to the solenoid if the valve does not open and the length of delay time which must be included before again attempting to open the valve. The control system continuously monitors the state of actuation of the valve by means of an inductance monitor for determining the position of the armature of the solenoid and, thus, the state of the valve.

Abstract: An apparatus for energizing the coil of, and detecting the resultant armature actuation in, a solenoid of the type having a movable armature reciprocable along an axis between first and second positions, a spring bias normally biasing the armature toward the first position, and an actuating coil for inducing a force on the armature tending to move the armature from the first position toward the second position in response to current flow in the actuating coil. A voltage is first provided to the solenoid coil and thereafter, a resulting current flow is differentiated and a zero crossing comparator is utilized to determine when the differentiated current is zero and, therefor, the time at which the sensed current flow reaches a maximum (dv/dt=0). The time at which the armature began to move in response to the resulting coil current may be inferred and the voltage to the solenoid coil interrupted a Predetermined time after the time at which the armature began to move.

Abstract: The operation of an electromechanical relay is synchronized with the power line waveform where an electrical power supply is supplied from a source to an electrical load. The current voltage supplied to the load is characterized by a power line waveform. An electromechanical relay is positioned between the power supply and the load where contacts of the relay are opened and closed to interrupt and supply power to the load. A microcontroller is positioned between a power source and the electromechanical relay and actuates the relay so that when the contacts are closed or opened the contacts are not exposed to an undesired voltage. A feedback control circuit senses the opening and closure of the contacts so that in the event the contacts, for example close at an undesireable point on the load current waveform the microcontroller adjusts for the necessary delay to cause the actuation of the relay to occur such that the contact closure is at the desired point in the load current waveform.

Abstract: A process for controlling and measuring the movement of an armature of an electromagnetic switching member with an excitation coil is proposed, which has the following steps: a current (i) or a voltage (u1) is applied to the excitation winding (3) in order to move the armature into a first actuatable position; before the start of the movement of the armature, the current or the voltage is raised above a value at which the armature remains in the actuated position, and before termination of the movement of the armature the current or the voltage is reduced to a defined value, which suffices to hold the armature in the actuated position; finally, the temporal variations in the current or the voltage are measured after setting of the defined value, for the purpose of recognizing the termination of the armature movement.

Abstract: Load driver circuit (10) has first and second comparators (Cphd 1, C.sub.2) which receive a load current signal (V.sub.s) indicative of current flowing through a load (11). The comparators provide, as output signals, set on and set off signals (at 21, 23) in response to comparing the load current signal (V.sub.s) with first and second thresholds (T.sub.1, T.sub.2). Driver circuitry (27, 43, 12) receives the set on and set off signals and provides a current control signal (at 18) for controlling load current. Preferably, disabling circuitry (30-34) disables the comparators (C.sub.1, C.sub.2) after and in response to the comparators providing their respective output signals (at 21, 23). Also, preferably enabling circuitry (40-42) enables the comparators (C.sub.1, C.sub.2) in response to comparing a sensed voltage (at 17), indicative of voltage at an output terminal of a switching device (12) that controls load current, with respect to a predetermined voltage (2.5 volts).

Abstract: A coil is connected to a voltage source by a switch enabled by a drive signal of fixed duration. Drive current in a coil is terminated by a chopper circuit if it reaches a predetermined peak level before the end of preselected rise time interval. The chopper circuit is inhibited from operation until the end of the rise time interval during which time the drive current is allowed to decay. The chopper circuit is enabled at the end of the rise time interval for chopping the drive current at an average peak current value for the duration of the preselected time. The total amount of energy supplied to the actuator is adjusted by allowing the current to decay if the peak current is reached before the end of the predetermined rise time interval and then by chopping the current at a predetermined switching rate for the duration of the preselected time of the drive signal. Short circuit protection is also provided during the predetermined rise time interval.

Abstract: Control circuitry is disclosed for electrical starters, contactors and the like having a starting winding and a serially coupled holding winding wherein the holding winding is shorted until the separable main contacts have closed which includes circuitry which obviates the need for relatively precise sensing of the position of the separable main contacts to control the holding winding. In one embodiment of the invention, the unshorting of the holding winding is delayed a predetermined number of cycles after the separable main contacts have closed to avoid the necessity of relatively accurate mechanical sensing of the position of the separable main contacts. In this embodiment a relatively less expensive field effect transistor or the like is used to short out the holding winding until the separable main contacts have closed. This allows the use of a relatively less expensive limit switch with a substantially smaller DC capability.

Abstract: An electric clutch actuator includes a coil having first and second windings, a first end of the first winding being connected to a source of electrical power and a second end of the second winding being connected through a switch such as an FET (field effect transistor) to ground potential. The opposite ends of the windings are connected together through another FET switch to the ground potential. An actuation circuit is responsive to a control signal to turn on the FET switches and cause electrical current to flow primarily through the first winding. The actuation circuit includes a timing circuit which turns off the FET connected to the opposite ends of the windings after a predetermined period of time to cause electrical current from the power source to pass through both of the windings.

Abstract: An apparatus is provided for precharging a filter capacitor to prevent damage to a set of contacts resulting from arcing across the contacts. Included is a coil, a set of contacts, and a battery, such that the contacts and filter capacitor are connected in series and the series connected combination is connected in parallel across the battery. Also included is a switch, and a microprocessor for producing a triggering signal responsive to the closure of the switch. A driving circuit receives the triggering signal and responsively produces a charging signal. A charging circuit receives the charging signal and responsively charges the filter capacitor. Thereafter, the microprocessor produces an energizing signal causing the coil to become energized and the contacts to responsively close. By precharging the filter capacitor before the closure of the contacts, the voltage potential across the contacts is reduced. Therefore, no damage occurs due to arcing across the contacts.

Abstract: The invention provides a sequential delayed power supplying circuit having the steps of driving the relay RY1 through a relay-driving part after delaying by the time-delay circuit the output of a rectifying part which rectifies the output of a direct current winding of a compound insulated transformer, and supplying alternating current power sequentially to a compound insulated transformer of the second set. Stabilizing the operation of the circuit may be possible, and connecting and driving an infinite number sets may be attained according to the present invention.

Abstract: A control panel enabling and automatically disabling system is coupled between a source of electrical power and a plurality of motion controls on an aerial work platform. Upon activation of a pushbutton type power enabling switch, power is coupled to all the motion controls for a predetermined fixed time period which when activated will couple power to a respective motion producing mechanism such as a boom actuator. If none of the motion controls are activated by an operator within this time period, a timer times out and the panel thereafter becomes inactive by interrupting the electrical power. However, if a motion command is effected by actuation of any one of the motion controls during this time period, the timer is automatically reset to zero time and held thereat until all motion commands cease, at which time the timer is restarted. The enabling switch cannot be defeated by a continuous activation thereof. The enabling switch must be released and pushed again to start a new cycle.

Abstract: A relay control for a cooking appliance having a heating element includes a sensor for detecting the occurrence of an arc upon a change of state of a relay coupled between the heating element and a power supply. Upon detecting an arc, the sensor provides a timing signal which is coupled to a microprocessor that controls the energization and deenergization of the relay. The microprocessor is responsive to the timing signal from the sensor to determine the time delay between the last energization/deenergization of the relay and the changing of the relay's state. From the time delay, the microprocessor determines a delay constant. Subsequently, the microprocessor energizes the relay at a time after the detection of a zero crossover point of the power supply signal, wherein the time is equal to the determined delay constant to cause the relay to change state at or slightly before a zero crossover point of the power supply signal.

Abstract: An electrically driving system for the outer rearview mirror erects or folds the mirror body by the operation switch for rotating the incorporated motor normally or reversively. The system comprises a momentary operation switch, normal and reverse relays and limit switches for disconnecting self-holding circuits of the relays and motors from a power source independently of one another by detecting erected and folded states of the mirror. When the normal or reverse relay is rendered operative by the momentary operation switch, the incorporated motors are driven to cause rotation of a plurality of the mirrors. The mirrors are stopped independently with disconnection of motor circuit caused by the action of the limit switches when they reach to the erected or folded state.

Abstract: An electrically driving system for the rearview mirrors, wherein the incorporated motors are rotated normally or reversibly in response to the operation of a operational switch, thereby erecting or folding the mirror bodies. The system comprises a momentary operational switch, a relay circuit, a group of limit switches for cutting off the relay circuit and motor circuit respectively by detecting erected and folded positions of the mirror bodies, and a circuit for judging a folded state. When the operational switch is pushed, any folded mirror is detected within delay time of the circuit for judging a folded state. And only when both of the left and right mirror bodies are in the fold positions, the erecting relay is actuated to rotate the motors in the erecting direction.

Abstract: The present invention pertains to a multi-stage solenoid in a housing having a first set of electrical contacts and at least a second set of electrical contacts. The solenoid also has at least two coil windings electrically distinct from each other and disposed sequentially in the housing. Additionally, the solenoid uses a timing circuit separately connected through a first set of contacts to each of the coil windings to control when they each receive electricity thereby activating the corresponding magnetically responsive element. The solenoid also uses a plunger having a flange of an electrically conducting material. The plunger is disposed in an original position in the housing in contact with one of the magnetically responsive elements.

Abstract: A safety control device for an actuator of a flap solenoid valve, such as for an automatic transmission. The device includes a current control device which is connected to a shunt resistor for measuring the current through the solenoid valve and the current control device. It also includes a control package which measures the time between the starting of the power to the solenoid valve and the moment when the current reaches a threshold intensity. The control package compares this time with a time range which indicates the proper operation of the solenoid valve so that if the time falls outside this time range, the control package instructs the current control device to cut power to the solenoid valve.

Abstract: A motor vehicle suspension control includes a solenoid actuator having an actuating coil connected in series with a transistor across an electric power source and circuit protection apparatus for the transistor. The voltage across the transistor is monitored, after a short time delay following turn-on, as a signal indicative of excessive current therethrough. If the signal so indicates, the transistor is turned off for a period of time and then turned on again for another try. This continues for a predetermined maximum number of attempts. Specific clocked digital circuitry is disclosed for controlling the operation and producing the different required time delays or counts.

Abstract: Automatic switching apparatus for a hand held electrically operated appliance such as a pressing iron. A motion sensor and an electronic timer cooperate to automatically shut off the iron if the iron remains stationary for a predetermined period of time. A simplified mechanism is manually operable in the event the user desires to reactivate the iron. A circuit board mounting simplified electronic circuitry is located within the handle of the iron. An appropriate indicator informs the user whether the iron is in the active mode or in the inactive mode.

Abstract: An electrical equipment controller is provided with a delayed turn-off capability. A thermostat is in series with a control relay. The thermostat is further in parallel with the series combination of a relay latch contact and a first positive temperature coefficient (PTC) device. A second PTC device is connected in parallel with the control relay. The arrangement of first and second PTC devices provides a predeterminable drop-out relay including compensation for ambient temperature changes.

Abstract: A new method of activating existing electric solenoids which reduces the power required up to 90%, reduces the size of wire required, extends solenoid life, and facilitates installation. This is accomplished by adding an encapsulated module at the end of the electrical line just ahead of the solenoid. The principles used are that a solenoid requires a much higher level of energy to actuate than to keep it actuated. Charging a capacitor slowly then allowing it to suddenly discharge into the coil eliminates the inrush load demanded on the source, while a series resistance then keeps the load at a low level by acting as a current limiter.

Abstract: A molded case circuit breaker includes a solenoid control circuit for controllably energizing a solenoid to actuate a motor operator to automatically move a handle of the circuit breaker to change the operative condition of the circuit breaker. The control circuit includes a monostable multivibrator that supplies an electrical pulse to the solenoid upon the receipt of a switching initiation signal. The time duration of the electrical pulse is controlled to be sufficiently long to assure proper operation of the solenoid and is determined by a timing circuit coupled to the source of operating voltage for the solenoid. If the operating voltage decreases, the time required to charge the timing circuit increases, increasing the duration of the electrical pulse of the solenoid to assure proper operation under low voltage conditions.

Abstract: A switching circuit with a time-delay device comprises a pulse generator, and a counter which receives pulses therefrom. The overflow output of the counter transmits a counter signal after receiving a predetermined number of pulses. The counter is provided with a holding circuit for maintaining the counter signal up to the time of resetting and renewed start of the counting operation. The resetting input of the counter receives a signal either by way of an inverter or directly. The overflow output of the counter is connected with the output of the time delay device, either directly to obtain a delayed start or by way of an inverter to obtain a delayed termination.

Abstract: A pair of interval timer units including a lower right timer (LRT) and a lower left timer (LLT) for controlling a pair of D.C. motors (RM, LM) to drive a pair of load devices accurately and consistently a predetermined lowering distance. The load devices are raised together until stopped by limit switches (LS1, LS2) but can be lowered individually under the interval timer (IT) control. Each timer unit (LRT) includes a voltage regulator (ZD1, ZR1) to provide a constant voltage to a ramp voltage generator (RG) and a reference voltage to a voltage inverter (VI). The ramp voltage is applied through a buffer (IC1B) to one input of a comparator (IC1C). The variable supply voltage is also applied to the voltage inverter (VI) that provides a time reference voltage that varies inversely with respect to variation in the supply voltage.

Abstract: A control system for eddy current coupling drive for armoured face conveyors wherein the systems controls a number of eddy current drives via a pair of power supply lines and a single pilot line. A main contactor controlled by a relay is held closed by contact of a pilot relay which is energized only if relay contacts in individual control units for each drive remain closed. These last mentioned contacts open if certain operating conditions are not met.

Abstract: A drive circuit for a latching relay includes a flip-flop, a timer and a semiconductive switching circuit for the relay. First and second input signals are applied to the flip-flop and first and second control signals at the output of the flip-flop are applied alternately to the timer as a time limit output for controlling the energization of the switching circuit in concert with a high-speed changeover signal.

Abstract: This disclosure depicts a novel abort cycle timer circuit for use with an AC source of electrical power and for operating electrical controls for machinery. The circuit provides a substantially DC voltage and current, first and second relays with normally open and normally closed contacts and a timing abort circuit. Opening a first of two switches causes the second of the two relays to energize after a time delay. Opening both switches causes the second relay to deenergize after a predetermined time. The novel circuit has improved immunity to electrical and magnetic noise.

Abstract: A control circuit for controlling the operation of an electrically powered heating device includes supply terminals for connection to a source of d.c. supply, one of the terminals of the heating device being connected to one supply terminal and the other terminal of the device being connected to the other supply terminal by way of a relay contact. The junction of the contact and device is connected by way of a resistor to one plate of a capacitor the other plate of which is connected to the one supply terminal. A comparator monitors the voltage across the capacitor and controls the operation of a relay winding. The comparator is supplied with a reference voltage which can be equal to the design operating voltage of the heating device, this being less than the nominal supply voltage. The relative values of the two resistors are chosen so that when the supply voltage exceeds the design voltage the power supplied to the heating device is controlled.

Abstract: An electrical switching and timing assembly is shown having a manually actuatable switch selectively closable and openable, an associated electrical circuit has an input end and an output end, the input end is intended for connection to a source of electrical potential while the output end is intended for connection to an electrical load, the associated circuit has a timing circuit effective for opening the associated circuit within a preselected span of time after the associated circuit has been closed by the manually actuatable switch, the manually actuatable switch being effective for opening the associated circuit even before the expiration of the preselected span of time; the circuit means, manually actuatable switch means, the input and output ends and timing circuit are carried by unitized support structure.

Abstract: A stand for an electric iron incorporates an automatic time delay safety switch arrangement which reduces the chances of fires being started by an unattended iron and serves to save a substantial amount of electric energy by cutting off the current to the iron when it is left turned-on but unattended. The stand includes a hinged, spring biased platform of insulating material for supporting an electric iron during non-use periods. Placement of the iron on the platform causes the platform to pivot closing a normally open switch. Closure of the switch energizes a standard electrically energized time delay relay mounted on the platform. After lapse of a predetermined time period, the time delay relay actuates a manually resettable electric relay from a first condition allowing the electric iron to be energized from a power supply socket on the platform to a second latched condition whereby the iron is deenergized.

Abstract: Automatic control apparatus for starting and then stopping and for continuing cyclical operation of an engine including two timer means, one for determining the running/not running ratio of the engine and the other for determining how long starting power is applied to the engine start system, typically the solenoid of a starter motor. One embodiment includes a vacuum switch for sensing and preempting the second timer operation when the engine is started and there is a vacuum present in the manifold. The preferred embodiment also includes adjustable controls for setting both timer means, these same means having switching contacts capable of carrying full power to the solenoid or other engine start component.

Abstract: A fail-safe electronic time delay circuit for providing a predetermined time delay period having an emitter-follower amplifier connectable to a source of recurrent signals, a voltage doubling rectifier for rectifying the amplified recurrent signals and for charging a capacitor which powers a tickler coil transistor oscillator, a pair of complementary switching transistors which are alternately rendered conductive by the a.c. oscillations of the transistor oscillator, a rectifier having a capacitor which is charged when one of the pair of complementary switching transistors is conductive and which is discharged through a vital relay when the other of the pair of complementary switching transistors is rendered conductive.

Abstract: An electronic timer having two electromagnetic relays is disclosed. The two electromagnetic relays are mounted on an insulating base plate. The electronic timer further comprises a delay circuit. At least one of the two electromagnetic relays is connected to an external power supply through the delay circuit. These two electromagnetic relays may be connected in such a manner that when connected with an external power supply, one of them is operated instantaneously while the other is actuated after a delay time, or in such a manner that both of them are simultaneously operated after a predetermined delay time, or in such a manner that they are operated after different delay times.

Abstract: A timed electric switch in a housing preferably for direct current loads such as for heating elements in vehicle windows, in which manually closable contacts supply current to the load and also to a digital timing circuit, which completes a circuit from said contacts through a holding solenoid for the contacts. After a predetermined count has been achieved in the timing circuit, the current supply through the holding solenoid is interrupted thereby releasing the contacts. Provision is made for allowing the second and subsequent timing periods to differ from the first timing period by independently supplying potential to the timing circuit, such as through the vehicle ignition switch. Reset of the timing circuit to produce the initial timing period once again is effected by switch off and re-operation of the ignition switch. An illuminated indication is provided, preferably by a light emitting diode, which operates when power is supplied to the load.

Abstract: A process for the protection of electrical systems upon return of power after power interruptions, through the immediate disconnection of secondary consuming units by an audio-frequency control receiver, and the subsequent reconnection thereof in timed sequence. The audio-frequency control receivers have, in addition to a normal control path, a second path, through which, upon return of the voltage, the switch relay for secondary consuming units is disconnected upon reaching 2/3 of the system voltage. The process may be implemented through the use of a two-state D.C. relay, which is controlled by a secondary path including a cold lead to the system voltage. The process may alternatively be implemented through the use of a two-state A.C. relay which is controlled through a half-wave secondary path including a capacitor/resistor parallel circuit.

Abstract: An inverse timer for a process line is disclosed in which the forward end of the material is detected at a known distance from an instrument which is to be activated. The inverse timer is initiated upon forward end detection, and in a small increment of time, .DELTA.T seconds later, the instrument is activated; .DELTA.T is equal to the time required for the material to move from the point of detection to the location of the instrument, i.e., the transport time minus the reaction time of the instrument. The inverse timer includes two potentiometers for independently adjusting the transport time and the reaction times. Since the velocity of the material may vary widely during production, the inverse timer enables rapid adjustments to be made to accommodate for these new conditions without the laborious empirical determination of optimum settings of interacting potentiometers.

Abstract: Electronically timed and electrically operated lamps are utilized in place of traditional candles. Actuation of a switch, located on each lamp holder, illuminates that lamp for an accurately timed predetermined period. One clock is utilized to drive a plurality of independent timers, each associated with an individual lamp. The lamp units are provided with the capability of being plugged into the timing unit, so as to permit interchangability.

Abstract: A fail-safe time delay circuit is provided to produce an output a predetermined time, and no less than a predetermined time after an input stimulus. The circuit includes a driving circuit for a pair of relays which are operated at slightly greater than 50% duty cycle and out of phase such that, except when the circuit is de-energized, at least one of the relays is always energized. The contacts of the two relays are employed in a balanced voltage amplifier to produce a bi-polar signal, with the magnitude of both polarities increasing, with the time required for the increase to a defined threshold establishing the time delay. A pair of threshold circuits are coupled to the output of the balanced voltage amplifier such that each threshold circuit (one responding to the positive portion, and the other the negative portion of the bi-polar output) is energized when the respective portion of the bi-polar signal is detected to reach the associated threshold.

Abstract: A three-terminal module contains a relay with normally closed switch contacts and a delay circuit for the coil which opens the switch. The module switch contacts are wired between the engine ignition switch and the ignition coil of the engine. Malfunction detectors energize the delay, which eventually energizes the switch-operating coil, thereby stopping the engine. Opening and reclosing of the ignition switch enables the engine to restart.

Abstract: This invention relates to a detecting element for a control device for invalids which detects without any physical contact the presence or the absence or even the displacement of a moving member within a sensitivity range in space, the size of the region in which this movement can be detected being large with regard to said moving member.

Abstract: In an electric safety switch circuit for use in apparatus having at least one safety switch for detecting at least one abnormal condition of the apparatus, switching elements are connected between a power source and the apparatus. The voltage of the main power source is transformed to a lower voltage and the switching elements are opened or closed by control circuitry in the low voltage circuit. The at least one safety switch is connected to the voltage transformer and the control circuitry such that the actuation of the at least one safety switch upon detection thereof of an abnormal condition actuates the control circuitry to open the switching elements and disconnect the apparatus from the power source.In one embodiment a primary switch is interconnected between the power source and the electric safety switch circuit, and in a modified embodiment the primary switch is connected in the electric safety switch circuit itself.

Abstract: A static trip unit for automatic electric circuit breakers includes an analog to digital converter for converting an analog signal proportional to the magnitude of current flowing in a distribution circuit to a digital signal having a pulse frequency proportional to the second power of the analog signal. When the analog signal exceeds a preselected threshold level, a binary counter is conditioned to accumulate the digital signal pulse. A decoder monitors the pulse count accumulating in the counter and issues a trip signal when the pulse count reaches a preselected total.