GB2032664A

GB2032664A - Electrical control apparatus

Info

Publication number: GB2032664A
Application number: GB7933980A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1978-10-17
Filing date: 1979-10-01
Publication date: 1980-05-08

Abstract

A control apparatus for the actuation of an electrical energy consuming appliance from a remote station comprises a sender unit, connected to an electrical mains power supply plug, to generate an oscillating signal of a particular frequency and apply it to the electrical mains power supply plug upon actuation of switch means, and a receiver unit connected between an electrical mains power supply plug and an electrical mains power supply socket or in an electrical energy consuming appliance. The receiver unit includes means responsive to the signal of the particular frequency generated by the sender unit to control the state of switch means. <IMAGE>

Description

SPECIFICATION Improvements relating to electrical control apparatus This invention is concerned with control apparatus for operating an electrical energy consuming appliance from a remote location. At present and, particularly on a domestic scale, it is necessary to run control wires between the appliance which has to be carried by the control wires. Recently various systems have come onto the market using radio, or ultrasonic waves to control remote electrical energy consuming appliances, and whilst these have been generally successful they are relatively complicated and expensive to produce.

have been generally successful they are relatively complicated and expensive to produce.

According to this invention a control apparatus for the actuation of an electrical energy consuming appliance from a remote station comprises a sender unit connected to an electrical mains power supply plug, the sender unit including switch means and an oscillating signal generator, the sender unit being arranged to generate an oscillating signal of a particular frequency and apply it to the electrical mains power supply plug upon actuation of the switch means and a receiver unit connected between an electrical mains power supply plug and an electrical mains power supply socket or in an electrical energy consuming appliance, the receiver including a switch means and frequency responsive means which is responsive to the signal of the particular frequency generated by the sender unit and which controls the state of the switch means, so that upon receipt by the receiver unit of a signal sent over the mains power supply wiring by the sender unit the state of the switch means is changed to establish or isolate an interconnection between the mains power supply plug and the mains power supply socket or enable or disable at least part of the electrical energy consuming appliance.

Thus the apparatus in accordance with this invention provides a simple "plug-in" unit the receiving unit of which is arranged to be plugged into the mains power supply beween the appliance to be controlled and the mains power supply whilst the sender unit is arranged to be plugged into any other power supply socket which shares a common power supply with the receiver unit. The normal mains power supply wiring is then used to carry a signal from the sender unit to the receiver unit to operate the switch means in the receiver unit. In this way as use is made of the normal mains power supply cables it is not necessary to lay any special control wiring to enable the appliance to be operated from a remote location.Further, the socket to which the sender unit is connected can be varied at will by merely unplugging it from one socket and plugging it into another socket at a different remote location.

This invention has particular utility in a domestic situation or in a factory where it may be desirable to operate an electrical current consuming appliance from a remote location.

The appliance may be a television, a warning bell, a light or any other appliance. Where the applicance is a large and expensive item, for example a television set, it may be more convenient to build the receiver unit into the television set as part of the set but, where the appliance is a light or some other simple, small appliance, or where it is intended to use the apparatus with a variety of different appliances, it is preferred that the receiver unit includes the electrical power supply socket so that the receiver unit is formed as a separate unit which can be plugged-in between the power supply socket and the appliance.For example, where the appliance is a normal tungsten filament electric light bulb, the receiver unit preferably has a mains power supply plug in the form of a male bayonet fitting provided at one end of the unit and a mains power supply socket in the form of a female bayonet fitting at the other end of the receiver unit. The receiver unit is then plugged into the light socket in place of the bulb and the bulb plugged into the other end of the receiver unit. Such a fitting enables the device to be fitted by a domestic user having no specialist knowledge of electricity and consequently, anybody who can connect and disconnect an electrical appliance is capable of making use of this invention.

The switch means on the sender unit may be formed by a manually operable switch so that the user can operate the manually operable switch to trigger the switch means or, alternatively, the switch means may be arranged to be triggered by some other device.

As an example of this, the switch means may be connected up to the switch of a doorbell so that, upon actuation of the doorbell, the sender unit generates an oscillating signal. Equally, the switch means may be connected up to a sensor circuit to detect the presence of an intruder or the presence of a fire or some other event and, upon detection of such an event, the sender unit will then generate an oscillating signal.

Instead of the switch means being connected to, for example, a doorbell, or some sensor, it is preferred that the switch means are connected to a sound detector so that the switch means is triggered upon the occurence of a sound. With the sender unit arranged in this way an oscillating signal will be generated by the sender unit in response to the detection of sounds and thus, the apparatus can be used as, for example, a baby alarm, or give an indication at a remote location upon the ringing of a telephone or, for example, upon a person calling at the house and knocking at the front door or ringing the doorbell.In any of these cases, in response to actuation of the switch means at the sender unit the receiver unit may be arranged to switch off the television set, or switch on the light or warning bell at a remote location in response to whatever has triggered the switch means in the sender unit, for example the cry of a baby, the ring of a telephone, or the ring of a doorbell.

Particularly when the receiver unit is incorporated into, for example a television set, the receiver unit may be arranged to disable the sound reproduction side of the television set upon receipt of the signal from the sender unit. This firstly gives an indication and secondly, particularly when the sender unit incorporates a sound detector, silences the television set to enable an observer to hear the cause of the sound trigger, for example a baby crying or a telephone ringing.

Preferably the receiver unit also includes a manually operable switch which is arranged to bypass the frequency responsive means and the switch means so that these can be taken out of the circuit to enable the appliance to be used independently of the sender unit.

The sender unit may be arranged to operate in conjunction with more than one receiver unit and, in this case, the sender unit may include more than one signal generator and associated switch means with each signal generator operating at a particular, different frequency, or alternatively, the sender unit may include means to vary the frequency of the signal generated by the oscillating signal generator and selector means to select the particular frequency to be generated in response to operation of the switch. With the apparatus arranged in either of these ways, more than one appliance can be operated from the same remote location and thus, for example, lights in different rooms of a house, or factory, can all be turned on or off from a single, remote location.

A simpler way of arranging the sender unit to operate more than one different receiver unit is for the sender unit to include a selector switch so that the oscillating signal generated by the sender unit may be applied between different pairs of the mains power supply wiring. For example, the oscillating signal from the signal generator may be applied between the neutral and earth wires of a mains power supply wiring or, alternatively between the live and neutral wires of a mains power supply wiring or even between the live and earth wires of a mains power supply wiring. Thus, by connecting different receivers between the appropriate pairs of the power supply wiring a different receiver will be actuated in dependence upon which pair of power supply wires the signal generated by the oscillating signal generator is impressed.

The sender unit may also include a timing mechanism connected to the switch means so that the sender unit can control the operation of one or more appliances at remote locations to any, particular, predetermined programme.

When the control apparatus is arranged in this way, it is of particular use as a burglar deterrent since the lights in various rooms of an empty house can be arranged to come on and off at various times during the hours of darkness to give an observer the impression that the house is inhabited.

The switch means in the or each receiver unit is preferably formed by a silicon controlled rectifier but it may be formed by a transistor or by a relay. When the receiver unit includes a silicon controlled rectifier, the simplest arrangement and one which is free from interference from transients occurring in the mains supply, is for the sender unit to be arranged to operate the signal generator throughout the period of time for which the receiver unit is to be actuated. However, the receiver unit may include a self latching relay or it may include latching means to hold the silicon controlled rectifier into its actuated condition, and in this case, the switch means in the sender unit are preferably arranged to operate the signal generator for a short period of time only.In this case, when the sender unit includes a manually operable switch it is preferably biased into the off position.

The oscillating signal generator in the sender unit may be formed by a simple feedback oscillator having its output coupled to the mains plug through a transformer. The receiver unit preferably includes a resonant circuit tuned to the predetermined frequency and which is arranged to provide a trigger signal to control the switch means in the receiver unit. The resonant circuit in the receiver unit is preferably coupled to the mains power supply plug through an isolating transformer.

Particular examples of control apparatus in accordance with this invention will now be described with reference to the accompanying drawings; in which: Figure 1 is a circuit diagram of one example of sender means; Figure 2 is a circuit diagram of one example of a receiver unit; Figure 3 is a circuit diagram of a simpler example of a receiver unit; Figure 4 is a circuit diagram of a sound triggered sender unit; Figure 5 is a circuit diagram of a further example of sender unit; Figure 6 is a further example of receiver to operate in conjunction with the sender unit shown in Fig. 5.

Figure 7 is a perspective view of the se k r unit shown in Figure 4; Figure 8 is a perspective view of a typical receiver unit; and, Figure 9 is a perspective view of an alternative simpler receiver unit.

In the first example of apparatus shown in Figs. 1 and 2, the sender unit comprises a feedback oscillator formed by a transistor T1, a resistor R1, capacitors C3 and C4 and a transformer TR 1. The transformer TR 1 has a split secondary winding, and one part of this is used to provide the feedback for the feedback amplifier whilst the other part is connected between the neutral and earth pins of a mains plug 1. Capacitors C1 and C2 are connected in series between the earth and neutral pins and the secondary winding of the transformer TR1, and block any direct current flow between the neutral and earth terminals of the mains plug 1.The power supply for the feedback oscillator is provided by a step-down transformer TR2 the primary side of which is connected between the live and neutral pins of the main plug 1 and the secondary side of which is connected to a rectifying and smoothing circuit formed by a diode D1 and capacitor C5. When a switch S1 which is included in the power supply for the feedback oscillator is closed, the feedback oscillator generates an oscillating signal and impresses it on the neutral and earth terminals of the mains plug 1. When this mains plug is connected in the normal mains power supply this oscillating signal is impressed upon the neutral and earth conductors of the mains power supply.

The receiver unit in this first example includes an isolating transformer TR3 connected between the neutral and earth pins of a mains plug 2 again with blocking capacitors C6 and C7 to prevent the flow of direct current and the secondary side of the isolating transformer TR3 is connected in parallel with capacitor C8. The secondary winding of the transformer TR3 and the capacitor C8 form a resonant circuit the resonant frequency of which is matched to that of the feedback oscillator in the sender unit. Upon an oscillating signal being received over the neutral and earth conductors of a main power supply, to which the mains plug 2 is connected and this oscillating signal causes the circuit formed by the secondary winding of the transformer TR3 and a capacitor C8 to resonate.A diode D2 provides a rectified signal at its output and this applied to the gate of a thyristor SCR1.

The thyristor is connected in series between the live pin of the mains plug 2 and the live pin of a mains output socket 3 and so, upon receipt of a DC signal level, exceeding a predetermined value on its gate, connects the live pin on the mains plug 2 to the live pin on the mains socket 3. The neutral pin on the mains socket 3 is directly connected to the neutral pin on the mains plug 2. Thus, upon receipt of a signal of a predetermined fre quency between the earth and neutral conductors of the mains power supply wiring the thyristor SCR1 establishes a connection between the mains plug 2 and the mains socket 3 to actuate any appliance inserted in the mains socket 3.In this example, the appliance is formed by a tungsten filament lamp LP1. A switch S2 is connected in parallel with the thyristor SCR 1 to enable the thyristor to be bypassed and thereby allow the appliance to be operated and so override the thyristor SCR1. An electrolytic capacitor C9 may be connected downstream of the diode D2 and this capacitor C9 helps to prevent the receiver unit being triggered by spurious signals present in the main power supply.With the capacitor C9 in the circuit the rectified signal level applied to the gate of the thyristor increases more slowly once the circuit formed by the secondary winding of the transformer TR3 and capacitor C8 starts to oscillate and thus, the capacitor C9 ensures that the receiver unit is only actuated when the oscillation in the resonant circuit formed by the secondary winding of the transformer TR3 and the capacitor C8 occurs at a predetermined period of time.

Figure 3 shows a receiver unit of more simple construction and this circuit is so simple that it can be incorporated into the cap of a tungsten filament lamp. The circuit comprises an isolating transformer TR4 connected in series with a capacitor C10 across the live and neutral terminals of the filament lamp. A thyristor SCR2 is connected in series with the filament of the lamp and both are again connected between the live and neutral terminals of the lamp. The gate of the thyristor SCR2 is connected to the secondary winding of the transformer TR4.When the sender unit is used with such a simple receiver unit, the oscillating frequency generated by the sender unit is impressed between the live and neutral connectors of the mains wiring and then the receipt of this oscillating signal by the receiver unit causes the thyristor SCR2 to be triggered to connect the filament of the lamp in circuit between the live and neutral terminals of the lamp.

Fig. 4 shows a sender unit incorporating a sound switch. A microphone 5 is connected to an operational amplifier 6. The output from the amplifier 6 is connected to the base of a transistor T2 having its collector connected to the gate of a thyristor SCR3. The thyristor is connected in series with the coil of a relay and the contacts of the relay are arranged to actuate an oscillator merely shown as a block 7. When the microphone 5 picks up a sound, there is a positive output from the operational amplifier 6 which switches on the thyristor T2 and, in turn switches on the thyristor SCR3 to close the contacts of the relay to trigger the oscillator 7. Thus, an oscillating signal is impressed upon the mains power supply to which a plug 8 is coupled.The power supply for the audio switch and oscillator is provided by transformer TR5, a diode D3, and a capac itor Cli. A feedback resistor R2, connected between the output of the amplifier 6 and another of its inputs together with the resistor capacitor chain R3, C12, ensure that the transistor T2 is biased in the on condition. An indicator lamp LP2 is connected in parallel with the resistor relay coil to give a visible indication when the relay is actuated. A manual push button switch S3 is connected in parallel with the contacts of the relay to enable the oscillator 7 to be triggered manually. A sensitivity control RV1 enables the sensitivity of the sound switch to be set so that the switch and hence the oscillator 7 is only triggered in response to a sound of a predetermined amplitude.

The example of the apparatus in accordance with the invention shown in Figures 5 and 6 is much more sophisticated and less liable to be affected by random transients and peaks that occur in the mains power supply. This example uses an amplitude modulated oscillating signal as the signal applied to the mains power supply wiring between the sender and receiver units. The sender unit includes a multi-vibrator circuit including the transistors T3 and T4 connected to an output transistor T5. The multi-vibrator oscillates as a frequency of 50KHz and the output of the transistor T5 is connected to the primary winding of a isolating transformer TR6. The transmitter is supplied with power from a step-down transformer TR7 and diode D4 and the multivibrator generates a signal formed by a series of bursts of 50 KHz oscillations, one on each alternate half cycle of the main power supply.

This output signal is applied to the mains power supply wiring through the isolating transformer TR6 which is connected across the mains power supply wiring through a pair of DC blocking capacitors.

The receiver unit for this example includes an isolating transformer TR7 connected across the mains power supply with a pair of DC blocking capacitors between it and the power supply and the secondary winding of the isolating transformer TR7 forms the input to a tuned amplifier having a resonance frequency of 50KHz and including the transistor T6. The output of the tuned amplifier is applied to a primary winding of a further isolating transformer TR8 which has its secondary winding connected to a rectifying and filtering circuit including a diode D5 which filters out the 50KHz signal and merely leaves the 50Hz modulation. This 50Hz modulation signal is then amplified in an amplifier including a transistor T7 the output of the amplifier fed to a rectifying circuit including diode D6 and capacitor C13 and thence to the gate of a thyristor SCR4.The thyristor SCR4 is connected in series with a coil of a relay the contacts of which are used to control the power supply to an appliance being operated from the receiver unit. The power supply for the receiver unit is obtained from a step-down transformer TR9 and a rectifying and smoothing circuit including the diode D7 and capacitor C14.

Upon receipt of a 50KHz signal modulated at 50Hz, over the mains power supply wiring, the 50KHz signal is amplified in the tuned amplifier including the transistor T6 and a strong signal applied to the isolating transformer TR8. The signal in the secondary winding of the transformer TR8 is rectified and filtered to remove the 50KHz signal and merely leave a signal oscillating at 50KHz, the modulation frequency of the initial 50KHz signal. This 50Hz signal is then amplified by the transistor T7 and rectified by the diode D6 and used to switch on the thyristor SCR4. The thyristor completes the circuit through the coil of a relay to cause the contacts of the relay to close and switch on the mains power supply to the appliance, which in this example, is a lamp.Naturally, the relay may be of the normally closed contact type in which case, upon the current passing through its coil, the normally closed contacts will open to remove the appliance from the power supply. Naturally, this version is preferred where the appliance to be connected to the receiver unit is, for example, a television set, where it is required that the television set be switched off in response to a signal from a remote location.

Fig. 7 shows a typical housing for a sender unit, particularly one including a sound switch. The sender unit is merely plugged into the mains power supply and then, either the manually operated switch S3 is used to trigger the appliance at a remote location or, alternatively, the sound switch is used so that the apparatus can be used as, for example, a baby alarm. A typical receiver unit is shown in Figure 8 and is simply a mains plug 2 which can be plugged into the normal mains power supply and a housing containing the control circuitry and an electrical socket which, in this example is shown as being a bayonet fitting socket to receive a normal tungsten filament lamp. However, this socket could as easily be a conventional 1 3 amp mains socket and this is naturally preferred where this is intended to be used for an appliance such as a television set, which would normally use such a socket.

The manual override switch S2 can be formed in an analogous manner to a conventional switched lampholder socket. Finally, the receiver unit shown in Fig. 9 demonstrates how conveniently the receiver unit can be arranged when it is intended to be used with a lamp having a bayonet fitting. All the electronic components are housed within the body hav ing a bayonet plug 9 at one end and a bayonet socket 10 at the other. Again, this example includes a manual switch S2 for enabling the lamp to be switched on locally.

Claims

1. A control apparatus for the actuation of an electrical energy consuming appliance from a remote station comprising a sender unit connected to an electrical mains power supply plug, the sender unit including switch means and an oscillating signal generator, the sender unit being arranged to generate an oscillating signal of a particular frequency and apply it to the electrical mains power supply plug upon actuation of the switch means and a receiver unit connected between an electrical mains power supply plug and an electrical mains power supply socket or in an electrical energy consuming appliance, the receiver including a switch means and frequency responsive means which is responsive to the signal of the particular frequency generated by the sender unit and which controls the state of the switch means, so that upon receipt by the receiver unit of a signal sent over the mains power supply wiring by the sender unit the state of the switch means is changed to establish or isolate an interconnection between the mains power supply plug and the mains power supply socket or enable or disable at least part of the electrical energy consuming appliance.

2. An apparatus according to claim 1, in which the switch means of the sender unit is formed by a manually operable switch.

3. An apparatus according to claim 1 or 2, in which the sender unit includes a sound detector coupled to the switch means so that in use, the switch means is triggered upon the occurrence of a sound.

4. An apparatus according to any one of the preceding claims, in which the receiver unit also includes a manually operable switch which is arranged to bypass the frequency responsive means and the switch means so that, in use, these are taken out of the power circuit to enable the appliance to be used independently of the sender unit.

5. An apparatus according to any one of the preceding claims, in which the sender unit also includes a timing mechanism connected to the switch means to enable the sender unit to control the operation of the appliance connected to the receiver unit to a particular, predetermined programme.

6. An apparatus according to any one of the preceding claims, in which the switch means in the receiver unit is formed by a silicon controlled rectifier.

7. An apparatus according to any one of the preceding claims, in which the oscillating signal generator in the sender unit is formed by a feedback oscillator having its output coupled to the mains plug through a transformer.

8. An apparatus according to any one of the preceding claims, in which the frequency responsive means in the receiver unit includes a resonant circuit tuned to the predetermined frequency and which is arranged to provide a trigger signal to control the switch means in the receiver unit.

9. An apparatus according to claim 9, in which the resonant circuit in the receiver unit is coupled to the mains power supply plug through an isolating transformer.

1 0. An apparatus in accordance with claim 1, constructed substantially as described with reference to the accompanying drawings.