Abstract: An electronic metal detector having a transmit coil (1) adapted to transmit an alternating magnetic field associated with a reactive transmit voltage, wherein the transmit voltage signal is selected such that the reactive transmit voltage is approximately constant for at least a time period during which a magnetic field signal to be processed is received by the detector for processing.

Abstract: An electronic metal detector having transmit electronics includes switching electronics arranged and adapted to generate a transmit signal. The transmit electronics includes at least two power sources, and is connected to a transmit coil arranged and adapted to transmit an alternating magnetic field. The switching electronics are adapted and arranged to switch a first voltage of one power source to the transmit coil for at least a first period and also a third period, and to switch a second voltage of the other power source to the transmit coil for at least a second period. Receive electronics are arranged to receive and process a receive magnetic field during at least some of the second period and fourth period to produce an indicator output, at least indicating the presence and a characteristic of some metal targets under the influence of the magnetic field.

Abstract: This invention relates to a vehicle security device. It relates, more particularly, to a security device or system which operatively serves as an alarm and/or immobilizer. The invention provides a vehicle security system including first and second parts, each including an electronic sub-circuit and a housing, and a communications link. In the operative configuration of the system on a vehicle, the first part is permanently mounted on the vehicle and the second part temporarily. The sub-circuits are interconnected via the link to define an integral control circuit, thus rendering the system operative. Should the vehicle be sold and the purchaser not require the system, the second part and the link may be removed and re-used by the seller. The value of only the first part is sacrificed by the seller. The system is aimed primarily at vehicle dealers.

Abstract: This invention relates to a vehicle security system. The invention provides a vehicle security system which can be armed and disarmed via a remote control device, e.g. an RF device. The system includes also sensing means which can sense a predetermined event indicative of the presence of a person at the vehicle, such as knocking on the vehicle. For disarming the system, it requires a disarm signal from a compatible remote control device as well as the predetermined event to occur within a predetermined short time period. Where a number of such systems are installed on a number of vehicles on the same lot, e.g. a dealership showroom, and are armed, one of them may be selectively disarmed via a remote control device common to all of the systems. Only the system which senses the predetermined event in addition to a disarm signal will be disarmed.

Abstract: A metal detector adapted to generate a transmit search signal and to receive a receive search signal, and to analyse such received search signal, wherein the detector is adapted to allow a selection of operating parameters for each of these functions, said selection being effected by the storage as data in a memory of such selection, characterised in that the detector is adapted to allow such stored data to be modified in accordance with data in an external store, further characterised in that there is a digital data communication transmission program, adapted to effect a transmission of some or all of the stored data through a data transmission means to enable a further metal detector to receive and store for use in such further detector the said data.

Abstract: This invention concerns a distributed stereo audio system (1). Distributed stereo audio systems are used to provide stereo sound to several rooms or areas from a single source of signal. The system includes two or more speakers (2, 3) for the broadcast of stereo audio signals; a source of stereo audio signals; a stereo amplifier (4) to amplify stereo audio signals and drive the speakers; and a mains operated electrical power supply (10) to provide power to the amplifier. The amplifier is located in the same room as the speakers, and remote from the signal source and power supply. The amplifier is connected to the signal source and power supply by means of a category 5 four pair twisted cable (11) which provides, in respective twisted pairs, right channel audio signals (12) from the signal source to the amplifier, left channel audio (13) from the signal source to the amplifier, DC power (14) from the power supply to the amplifier, and control signals (20) from the amplifier to the signal source.

Abstract: A case for a folding-type mobile telephone is shown which is divisible into two sections, each section having a room. The room of one section is for the body of the phone and the room of the other section is for cover. Each section has elastic portions and the sections snap together so that the case can fit a wide variety of phone models, regardless of size. An antenna fixing strap is also provided so that the phone will not easily fall out of the case.

Abstract: A method and apparatus is provided for electrically stimulating magnetotherapy to a living body. The apparatus comprises a permanent magnet and a coil of D-block transition metal surrounding the permanent magnet. A voltage is applied across the coil in a direction to enhance the magnetic flux in the permanent magnet. The negative charge of these free electrons is thought to attract the positive electromagnetic charge of the enhanced magnetic flux so a magnetic flux can be electromagnetically transferred with the electron flow through the permanent magnet and conductors through the terminals to enable the magnetic flux to pass to and through the living body. The circuit has an output circuit which will assist the flow of the magnetic flux through the living body. The output circuit has two coils which boost the magnetic flux to thereby assist the flow of the magnetic flux.

Abstract: A timing apparatus for providing timing information to a moving person (11) moving past a datum line (13). A radiation source (15) located at the datum line (13) emits modulated radiation in a diverging conical radiation zone (16) across a path (12) along which the person moves and straddling the datum line (13) across the path (12). A radiation sensor (21) located on an aerial (22) receives radiation emitted by the radiation source (15) as the radiation zone (16) is crossed and generates a sensor signal (21a). A radiation detector circuit (26) receives the sensor signal (21a) and is tuned to discriminate the modulated radiation from the radiation source (15) and to generate a detector signal (26a) for as long as radiation from the radiation source (15) is being received and detected.

Abstract: A security system includes a plurality of sensors each capable of providing a detection input signal adapted to cause activation of the alarm system, a circuit for inhibiting activation of the alarm system as a result of a first detection input signal, and a circuit for removing the inhibition and allowing activation of the alarm system in response to a second detection input signal from any one of the sensors, including the sensor that provided the first detection input signal. A first alarm device is located essentially indoors on the premises to be protected and a second alarm device is located outdoors on the premises to be protected. The inhibition circuit allows activation of only the indoor alarm device, but a further detection input signal from one of the sensors within a predetermined time activates the outdoor alarm device.

Abstract: A monitoring system of the type suitable for use in monitoring signals from security installations or networks includes a central control station serving a plurality of users and to which the users are connected by an existing telephone network or some other form of direct or switched line connection. Each user is provided with an encoder in the form of a combined control unit and digital telephone dialler, said encoder being programmed with information concerning each user in principally alphabetical character form to increase the likelihood that the message will be received and understood even in the event that certain characters contained in the message are missing. The control station is equipped with means for receiving and decoding the message transmitted from the user's control unit together with visual display means, such as a VDU or line printer, for visually displaying the received message.

Abstract: A fast-operating, minimally complex circuit for automatically clamping the P wells of a CMOS integrated circuit to the most negative potential of the overall circuit. Each of a plurality of N-channel control transistors has its drain connected to a respective one of the circuit nodes whose potential may be the most negative at any given time. The source terminals of all of the control transistors are coupled to a common negative supply bus which is connected to all of the P wells in the integrated circuit. The gates of all of the control transistors are held at a potential which causes them to conduct drain-to-source current. If one of the nodes suddenly drops in potential, the respective control transistor conducts a current in the reverse direction which lowers the potential of the common bus to approximately the potential of the respective node. The respective control transistor conducts heavily until the common bus is thus clamped, and then conducts just enough current to maintain the clamping.

Abstract: A flow gauge for measuring the mass flow rate of freely flowing material, falling through a path, said flow gauge comprising a pair of sensors spaced longitudinally along the chute, the sensors being connected to a computing means for receiving the output of each sensor, where said output is a measure of the density of the flow at the location of the sensor, the computing means utilizing the output of the sensors to provide a measure of the mass flow rate, said sensors comprising a radiation source and a radiation detector in opposed relation to the source and on the other side of the flowing material from the detector, for detecting the radiation passing through the flowing material.