Abstract: A circuit for providing controlled switching of power applied to a load is adapted for actuating and deactivating a power switching circuit in response to a command signal. The circuit employs a switching circuit having a time delay section operable to terminate application of power immediately upon the cessation of a control signal and to conduct current after a predetermined delay interval after receipt of a command signal. The circuit is adapted for use with pyrotechnic ignition systems in which it is desired to quickly discharge capacitive elements connected to a load for prevention of undesired and possibly hazardous build-up of heat in a resistive ignition element.

Abstract: An electronic time switch for the time-limited actuation of appliances which are supplied with alternating current, whose load component is actuated by an electronic control element, and which includes terminals which supply the load component as well as the control element. A first storage element is charged during the inoperative condition through a rectifier, wherein the first storage element charges a second storage element upon initiation of load operation through the intermediary of a pushbutton with switching functions, through a recharging branch having a current limiting resistor. The recharging branch consists of a parallel circuit including an ohmic resistor and a threshold rectifier.

Abstract: A microcomputer-based electronic controller for a dishwasher utilizes a motor driven timing cam for selectively energizing the electromechanical components of the dishwater. An internal diagnostic routine in the microcomputer insures that the timing cam is advanced when the microcomputer calls for power to be applied to the motor.

Abstract: An electrical timing circuit for controlling the activation and deactivation of an electrical load by setting a predetermined time period for which the load will be on and for providing one or more short warning periods wherein the load is deactivated prior to the expiration of the predetermined time period. The invention may be used as a switch for a light whereby the light may be actuated to remain on for an hour, but just prior to the expiration of hour period the light will momentarily go off for one or more warning periods prior to the light being turned completely off so that the switch may be reactuated to start another timing period. Momentary switches (12) control a set-reset circuit (16) which sends a signal to a NAND gate (18). A timing circuit (20) is responsive to the momentary switches (12) to provide a plurality of time spaced-signals.

Abstract: A switching timer device includes a manual switch having "on", "off" and "timer" positions. When the switch is set in the "on" position a load is supplied continuous power from a source. When the switch is set in the "timer" position, a load-powering power switch is closed for a predetermined length of time determined by a timer that is automatically reset when the manual switch is so actuated, and after elapse of the predetermined time the power switch is opened to de-energize the load. The timer is configured as a direct replacement for existing wall-mounted switch units without requiring access to the low side of the line, and consumes no internal power when in the normal "on" position.

Abstract: In a well such as an oil well, a timer connects a power source to the motor which drives the well pump for timed energization and de-energization periods. The timer consists of an electronic programmable timer having a stored program data processor for processing digital information and with capabilities to variably enter time program data into the processor to selectively energize and de-energize the pump motor for any desired time intervals for each day and the time intervals for each day of the week may be programmed differently. When the pump motor is provided in the form of an electric motor, a power transducer is connected to the power source energizing the motor to continually monitor line voltage and current and provide a true power output signal representative of the phase angle between the line voltage and line current.

Abstract: The timer controls a dispensing machine and in particular controls the dispensing cycle for a product such as coffee, a beverage, or instant mashed potatoes. The control includes regulation of the water portion of the cycle and the solid or powder portion of the cycle. The timer is controlled by a plurality of touch switches each coupling via a resistor network to the control logic of the timer. The control logic is preferably CMOS-type having a high input impedance permitting use of a resistor network of high resistance to limit current flow especially under fault. The touch switches control functions such as "hot water", "large portion", "small portion", "stop", and "push and hold".

Abstract: A wholly automatic commercial laundry in which soiled laundry is automatically routed to available washing machines, is automatically unloaded, conveyed, and loaded into one of several dryers which is available, or is conveyed directly to a finishing station when drying is not required. A unique programmable selector permits selecting any of several preprogrammed washing cycles, and modifying these cycles in accordance with the laundry to be washed. The selector also provides the necessary information for routing of the batches of laundry from the washing machines to the dryers, for selecting one of several drying cycles, and for routing the laundry to a desired finishing station.This is a division of application Ser. No. 903,115, filed May 5, 1978 now U.S. Pat. No. 4,195,498 issued Apr. 1, 1980.

Abstract: A food processor is comprised of a food processing cutter which is driven by a motor connected to an AC power source, a switch for controlling on and off of the motor, a pulse generator for forming count pulses having a given period from the AC power source, a set switch, a start switch, and a timer which operates the start switch at a time point set therein to start the rotation of the motor. Further, the food processor includes an up-counter for counting the count pulses while the set switch is operated to store a driving time period data of the motor, and a down-counter to which the stored data of the up-counter is transferred when the start switch is operated by the timer. The down-counter counts down the data every time it receives the count pulse and produces a drive stop signal for the motor when its contents become "0".

Abstract: A timing controller which supervises the reclosure of a fault responsive circuit breaker which includes a plurality of selectable switches for developing signals representing the reset and reclose delay times for the recloser relay operatively associated with the fault responsive circuit breaker; a plurality of multiplexers for receiving the signals developed by the selectable switches and for developing serially formatted digital words in accordance with such signals for delivery to an output controlling multiplexer; a first counter assembly for regulating the output of the output controlling multiplexer in accordance with the condition of the recloser relay; a storage device for receiving and storing the output of the output controlling multiplexer; and a comparison device for comparing the stored output of the output controlling multiplexer with a second counter assembly which develops a timed output signal.

Abstract: The invention is an improved control for an air conditioner unit in an automobile. The control operates on a time cycle basis instead of using a sensor of air temperatures. The installation is simple, requiring the severing of an electrical lead in the automotive electrical system and making three electrical connections from the invention to the wiring of the automotive electrical system. The invention consists of an adjustable range control, an interval timer, and a relay driver. This combination is connected to the magnetic clutch of the air conditioning unit.

Abstract: A control for an outdoor lighting fixture which adds an extra off-on cycle to that imposed by a photoelectric cell control. At a predetermined time during the on period of the lighting fixture, the lamp of the fixture is shut off. This shut-off time had previously been determined as one during which traffic in the area is at a minimum. A set time after the shut off, the lamp is lit once again, this time being selected as a time when traffic is re-appearing. When the ambient light reaches the shut-off level of the photoelectric cell, the lamp is shut off for the day. In this way, the lamp is turned off for a timed period for the purpose of reducing the energy required by the lamp for the dark hours of the night.

Abstract: Conservation system for use with a power source which supplies power over premises wiring to utilization equipment such as lighting equipment. Contactors and a control system are provided to temporarily interrupt the supplying of power from the power source to at least a portion of the utilization equipment. At least one switching circuit is connected in series between the power source and that portion of the utilization equipment. The switching circuit is responsive to the temporary interruption of power to open the circuit between the power source and that portion of the utilization equipment and to maintain that circuit open after the temporary interruption of power ceases, thereby automatically deenergizing that portion of the utilization equipment upon interruption of the power.

Abstract: A timing apparatus for holding a door open for a controlled period of time before releasing it for closure. The timing apparatus includes a switch operable to produce a switching signal. A first energizing control is coupled to the switch and is responsive to the switching signal for producing a first signal. An electromagnetic device is coupled to the first energizing control and is energizable in response to the first signal. A first timing circuit is coupled to the first energizing control and is responsive to the first signal to generate a first timing signal of predetermined duration and corresponding to the switching signal. The first energizing control is further responsive to the first timing signal thereby to remain in the state of providing the first signal for such predetermined duration. A second timing circuit is coupled to the first timing circuit and is responsive to the termination of the first timing signal to produce a second timing signal of second predetermined duration.

Abstract: A system for the control of a load such as a heating or cooling plant in response to changes in an external parameter, specifically ambient temperature, comprises a loop circuit with two conductors connected at an input end across a power supply and at an output end across a switching network, the load being inserted in one of these conductors. A high-impedance voltage multiplier connected across these conductors downstream of the load, in parallel with the switching network, supplies the necessary operating voltage to a parameter sensor such as a thermostat even when that network is in a low-impedance state so as to draw a maximum load current. The switching network may include a voltage clamp provided with a source of reference potential, e.g. a primary battery, which upon failure of the normal power supply can act as a standby supply insuring continued operation of a timer serving for a periodic switchover between different temperature thresholds for the thermostat.

Abstract: Disclosed is a muting circuit, in which the generation of click noise is prevented in that the muting operation is caused to occur at an instant when the instantaneous level (i.e., waveform level) of the input audio signal becomes zero for the first time since the appearance of a muting signal.

Abstract: An equipment protector and energy saving apparatus includes transient protection as well as under voltage protection by preventing the reduced voltage from being applied to motors and other apparatuses that may be damaged because of insufficient voltage being applied thereto. Provision is incorporated to protect for momentary low voltage transients and turn-on prevention, if the line voltage should be reduced below a predetermined value. Provision is also made for correcting for a small increase in line voltage which may occur when the operating equipment is removed from the line. A timing device may be incorporated therein in order to remove the protected equipment from the line for predetermined intervals of time.

Abstract: A timer switch comprises a drive gear secured to an interval shaft rotatably mounted on a casing. A first clutch gear is rotatably mounted on a bushing which is rotatably mounted on said casing. The first clutch gear is in mesh with the drive gear. A second clutch gear is fixedly mounted on the bushing for rotation therewith and disposed in closely spaced opposed relation to the first clutch gear. The second clutch gear is operatively connected to an electric motor. A slip friction clutch in the form of a flat resilient plate is interposed between and frictionally engages the opposed first and second clutch gears so that the slip friction clutch is deformed into an arcuate cross-section. The slip friction clutch urges the first clutch gear away from the second clutch gear into frictional engagement with the bushing.

Abstract: This invention relates to a program selection apparatus for program-controlled household appliances, such as washing machines in particular, which have a numeral keyboard for the input of program specifications and which have a display device coupled therewith via a control device for a continuous display of the program specifications inputted in sequence via the various keys of the numeral keyboard.

Abstract: Circuit for the delayed switch-on of a supply voltage in an electric apparatus which has at least a first and a second supply terminal, the series arrangement of the emitter-base path of a first transistor and the collector-emitter path of a second transistor being arranged between the first and the second supply terminals, the base of the second transistor being connected to a voltage divider provided between the collector of the first transistor and the second supply terminal.

Abstract: A delay circuit comprising two leads adapted to be connected across a light switch for delaying the turn off of a light bulb after the switch has been turned off. A silicon controlled rectifier (SCR) is connected across the two leads for applying power to the bulb when the SCR is on. An integrated circuit including an oscillator and a counter provides an output to the gate of the SCR for a predetermined time period following the opening of the switch for enabling the SCR to turn on.

Abstract: A device for producing a gradual change in power supplied to a load which utilizes at least one gated solid state switching device and a selectable variable timer network connected to the gate electrode and comprising a chargeable capacitor and a switchable resistive network, for controlling a light circuit, for example.

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 time delay switch capable of connecting a consuming device to a power source via a first current path for a predetermined time and including a first normally open circuit breaker connected in the first current path. A second current part is provided including the first normally open circuit breaker and an auxiliary normally closed circuit breaker connected in series with a thermal element made of a memory alloy characterized by a two-way temperature sensitive shape changing characteristic and a resistive heater electrically connected in series with the thermal element and thermally coupled thereto. A push-button activator is provided which upon actuation thereof closes the contact of the first circuit breaker resulting in current flowing in the first and second current paths, thereby producing heating of the thermal element and a corresponding shape change therein.

Abstract: A timed switch for controlling an electric load has a relay mounted within the switch housing. The relay has a pair of contacts which are connected to the load, a movable core connected to one of the contacts and a holding coil which holds the core in and holds the contacts closed when energized and releases them when deenergized. The switch also has a timer; and a manual actuator for moving the core and closing the contacts, actuating the timer and actuating the relay coil. The timer is connected to the relay coil to deenergize the coil and release the contacts upon expiration of a predetermined interval measured by the timer. The contacts may also be opened by actuation of the manual actuator without having to overcome the holding force of the relay coil on the core.

Abstract: A control system for an appliance having a plurality of different operational cycles, provides cam operated switches for controlling the coupling of electrical power to the appliance, the switches including a plurality of rotatable cams for operating the switches in response to the rotational position of the cams, the switches being adapted for electrical rotation of said cams, a digital electronic control circuit for controlling the electrical cam rotation, the control circuit including circuitry for receiving a selection of any one of the cycles for the operation of the appliance, and a second circuit coupled between the switches and the control circuit and responsive to the circuitry for receiving for supplying information on the rotational position of the cams to the control circuit to enable control of the electrical rotation in accordance with a cycle selection.

Abstract: Process timing and controlling system for use in photographic darkrooms involving multiple timing and control process steps including a control console, programmable in at least one channel to step through substantially all timing and control process steps, timing means in at least one channel for measuring time remaining in a particular process step, timing indicator means in at least one channel for indicating time remaining in a particular process step, a source of power connecting the console and the timing means which when activated supplies power to the console and timing mean, means for initiating a program step in at least one channel, switching means in at least one channel for stepping through the steps independently of the programmed time, a plurality of relays for operating programmed timing and control functions, and relay driving means programmed to select an appropriate output to activate the relay.

Abstract: A system for alternately activating and deactivating a load comprises a high-resistance d-c circuit branch connected across a power supply downstream of a load-operating impedance, this branch including a voltage limiter and a voltage multiplier in series with each other and with a switching stage responsive to commands from a timer and/or a parameter sensor such as a thermostat. The junction of the voltage limiter and the voltage multiplier is connected to one input of a differential amplifier whose other input is energized with either of two potentials, respectively higher and lower than that of the junction, by the switching stage.

Abstract: A rotating cam member incrementally moves through a discrete plurality of angular positions to sequentially actuate in a predetermined pattern an array of switches controlling, for example, the operation cycles of a domestic appliance such as an automatic dishwasher or clothes washer. The rotating cam member is driven from one angular position to the next by a motor under the control of a programmable integrated circuit timer determining the dwell time of the cam member at each of its angular positions. Varying the dwell time of the cam member at each of its angular positions readily permits a more flexible and complex operating cycle sequence for the appliance being controlled as compared to prior art electromechanical timer devices.

Abstract: In a process in which a feedstock is provided through a desalting unit prior to introduction into a fractional distillation column, the feed stream flowing to the desalting unit is split and passed through multiple heat exchangers. Method and apparatus is provided for maintaining a desired effluent flow rate out of the desalting unit and for maintaining the temperatures of the split feed streams substantially equal. After passing through the desalting unit the feed stream may again be split and passed through multiple heat exchangers prior to introduction of the feed stream into the fractional distillation column. Method and apparatus is also provided for maintaining the temperature of the split feed streams provided from the desalting unit substantially equal.

Abstract: A coin slide actuated timer mechanism is provided for a commercial apparatus such as an automatic fabric drying machine. The timer mechanism includes an indexing mechanism by which preselected angles of timer drive shaft rotation corresponding to desired periods of machine operating time can be manually preset. A movable peg member can be placed in various angularly spaced locations on an index wheel which correspond to the desired periods of operating time and when the timer drive motor is energized the index wheel will be rotated with the timer drive shaft to move the movable peg member into engagement with a switch actuator for initiating the termination of the time period. The index wheel is rotatably biased upon the timer drive shaft for resetting to a start posture upon actuation of a coin slide actuator.

Abstract: An electrical timer automatically actuates an output electrical load device such as an electric light according to a program stored as markers in a memory unit over a 24-hour interval, whereupon the program is recycled. By actuating one or more electric lights within an empty dwelling, an illusion of occupancy is thus conveyed to an observer. In the preferred form of the invention the memory unit is a recirculating shift register. A daily variability of the timer output is provided to prevent precise daily replication of the load device duty profile. One version causes the program output to be delayed by 15 minutes on alternate days by alternately taking the output from the last or the next-to-last storage element of the shift register. The stored duty profile is in 15-minute blocks.

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.

Abstract: A momentary ON rocker button switch (2) with bimetal detent latching (36) in the ON position and releasable by a heater (42) wound on the bimetal (36), the heater (42) being controlled through the output of a solid state timing circuit (TC, R1, C1) housed in the switch which is energized upon closure of the switch contacts (14a, 18).

Abstract: One form of the timer is designed to be mounted over and behind a conventional wall switch cover plate and includes a two position timer condition-setting arm, a rotatable and depressible time setting dial knob and an indicator on the front of the cover plate. When the arm is moved to a timer-on position, the indicator flashes to indicate that timer programming is needed. This may be achieved in real time over the first twenty-four hours after a 30 minute play period by depressing the knob acting as an on and off power switch control push button to turn the light circuit on and off in a normal manner. Fast normal programming is achieved by rotating the knob to various time settings and depressing the knob to set ON or OFF markers in timer memory.

Abstract: A delay circuit comprising two leads adapted to be connected across a light switch for delaying the turn off of a light bulb after the switch has been turned off. A silicon controlled rectifier (SCR) is connected across the two leads for applying power to the bulb when the SCR is on. A capacitor is connected to one of the leads for controlling circuitry coupled to the gate of the SCR for turning the SCR on for a given time period following the opening of the switch. A quick discharge circuit is provided for rapidly discharging the capacitor when the switch is closed.

Abstract: The control circuit is preferably provided in an integral unit with a momentary on-off switch, preferably inside a switch housing box and adapted to replace a common wall switch to provide for the automatic turn-off of the light or other load operated by the switch after a presetable period of time. The circuit is constructed so as not to require a third wire (usually a power lead) at the unit. The use of low power logic circuit controls, employing preferably CMOS chips enables use of a capacitor storage element of manageable size, with very low power consumption of the circuit in its "off" state. The "on" duration of the light is adjustable over a suitable time range and the circuit is further characterized by a "flashing" period preceding total turn-off.

Abstract: A programmable memory for the automatic control of a heating or cooling plant over a 24-hour, 7-day or longer cycle comprises a frame with a multiplicity of mutually parallel printed-circuit strips whose major surfaces carry two sets of conductors arrayed in an orthogonal matrix, the strips being overlain by a cover plate with slits for the insertion of jumpers bridging selected conductors at their points of intersection. The conductors of one set are sequentially energized while those of the other set are rapidly scanned to detect an output signal representing a selected time in the program cycle at which a command for a change in thermostat setting is to be emitted. The cycle is established or modified by a program plate superimposable upon the cover plate to block some of its slits and/or to actuate one or more switches correlating the several matrix outputs with respective clock readings different for the various cycles.

Abstract: Cyclic electric time switch means has a housing with an electrical clock therein and trip contact means comprising a toothed gear wheel coupled to a drive gear of the clock and mounting gear wheel. The disc mounts an electrical switch having contact terminals slidingly engaged with conductive tracks of a further settable disc and connection means are provided to connect a device to be supplied with power under the control of the time switch means. A trip arm is provided on the gear wheel to operate the electrical switch in one position of rotation of the gear wheel according to the setting effected by a manually settable control knob. A delay circuit provides, at the end of a delay period following operation of the electrical switch, restoration of the electrical switch via electromagnetic means for repetition of the operation by the trip arm when the gear wheel again reaches said one position of rotation.

Abstract: An energy-conserving solid-state-controlled illumination system which operates high-intensity-discharge lamps. The system operates the lamps at about a predetermined rated power consumption with a relatively high light output for a predetermined initial period of time during the initial night when a high degree of illumination is most needed. The system then operates the lamps for a later period of the night at a reduced power for a second predetermined period of time when a lower degree of illumination can be tolerated. Then if the lamps are still energized according to seasonal variations, the system thereafter operates the lamps at the relatively high light output for the remainder of the night to accommodate early morning traffic.

Abstract: A timer comprising a non-directional synchronous clock motor, an operating arm projecting radially from the motor shaft, a motor control switch controlling power supplied to the motor and engaged and opened by the arm when said arm is in a normal position, stop means spaced radially from the shaft and circumferentially from the control switch to limit turning of the arm in a direction away from the control switch and to cause the motor to rotate in the opposite direction and the arm to turn back to said normal position, a service switch in a power line to related timed means and positioned relative to the control switch, stop means and arm to be engaged and operated by the arm when said arm is in a predetermined position within its travel between said control switch and stop means and starter means connected with said power supply to energize the motor and initiate turning of the arm away from said normal position.

Abstract: A load demand control system for limiting the total average electric load over a moving predetermined time interval to an installation having at least one large load device, making use of a timer control which can be selectively operated by an operator upon the need for the operation of the one large electrical load. The timer control first resets the control point of the load demand control of the installation at some low predetermined value. Subsequently, the timer control turns on the large load for a predetermined period of time and after its operation, the timer control maintains the low predetermined value of the load demand control for a further predetermined time period whereby the total moving average electrical load to the installation for the total time interval of the timer control is maintained below a predetermined peak electrical load value set for the installation.

Abstract: A circuit arrangement for a windshield cleaning installation of motor vehicles with a switch which, in one engaging position, connects a program transmitter for one function by way of a control line with one terminal of the power supply and which, in a second engaging position, connects the program transmitter for another function by way of the same control line with the other power supply terminal; the program transmitter is equipped with switching devices for realizing the various functions corresponding to the potential applied to the control line.

Abstract: An apparatus for providing a time-controlled output based primarily upon a primary time source and secondarily upon a secondary time source, the secondary time source counted down to the desired frequency of the time-controlled output. A sensor supplies a control circuit which outputs the primary time source signal when the primary time source is operative, and the secondary time source signal when the primary time source is not operative. The output of the control circuit then resets the appropriate segment of the secondary time source counter in order to synchronize the time-controlled output for the primary time source when the primary time source is operative.

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: The maximum voltage stored in a timer storage capacitor during charging is limited to a fixed level independent of battery voltage by the junction drops of a plurality of forward biased solid state devices. The discharge time of the timer storage capacitor to a predetermined triggering level is thus also independent of battery voltage. At the triggering level, control and drive circuits interrupt the supply circuit to an electric device.

Abstract: Electrical power supply for use with apparatus which transmits a predetermined message. When an input signal is received, a source of electrical energy is connected to a power output terminal by turning a switching transistor on. A latching circuit holds the transistor on after termination of the input signal. Elements of the apparatus which are connected to the power output terminal to obtain operating power transmit the predetermined message when the electrical energy is supplied to the terminal. When the transmission is complete, the apparatus produces a termination signal to the latching circuit causing it to turn the switching transistor off and thus disconnect the source of electrical energy from the power output terminal.

Abstract: A controller is disclosed for controlling the operation of selected electro-mechanical devices without the use of a microprocessor or similar computing machines. The controller includes a memory programmed to output a data word each time the memory is advanced to its next successive memory address. Responsive to the data word, an electro-mechanical device, identified by the data word, is actuated to perform its function. As the function of an electro-mechanical device is completed, a sensor develops a control signal for altering the internal count of a counter. The counter, in turn, advances the memory to its next address for outputting its next data word. The cycle continues as the memory is advanced through its addresses and selected electro-mechanical devices are successively actuated to perform their assigned functions.

Abstract: The apparatus may be embodied as a self-contained unit associated with the television set or integrated into the television set. The control is basically in two functions, one which is set for programming the availability of use of the television set at predetermined time intervals of the day, and the other which is set for controlling total usage of the television set over a given period such as a 24-hour period. In the preferred embodiment the two functions are set and repeated automatically every day. In another version different settings are allowed for both control functions for weekdays and weekends. In still another version each day of the week may be set separately with regard to both control functions.

Abstract: A timing circuit for sounding an alarm for left-on main power switches, particularly in aircraft, includes a detector circuit for a secondary circuit of a complete circuit, a clock circuit controlled by the main power switch and an audioalarm circuit activated by the clock circuit when the main power switch is left on for a predetermined time following shut off of the secondary circuit.