Abstract: The circuit is of a loop-mountable unit of a fire alarm system, and includes: an adjustable current source, arranged to adjust the current from the loop through the power control circuit based on a control signal; an inverting amplifier, arranged to provide the control signal to the adjustable current source in which the control signal is based on the loop voltage; and a damper having an input for connection to a loop and an output connected to the inverting input of the inverting amplifier such that the voltage at the output of the damper is smoothed with respect to the voltage at its input.

Abstract: The circuit is of a loop-mountable unit of a fire alarm system, and includes: an adjustable current source, arranged to adjust the current from the loop through the power control circuit based on a control signal; an inverting amplifier, arranged to provide the control signal to the adjustable current source in which the control signal is based on the loop voltage; and a damper having an input for connection to a loop and an output connected to the inverting input of the inverting amplifier such that the voltage at the output of the damper is smoothed with respect to the voltage at its input.

Abstract: The system includes an active unit, such as a detector unit, which has a processor, a network port for connection to a central control unit, and an optical data input port. The processor is arranged to enable the optical data input port on receipt of an enable signal received by the active unit from the central control unit via a network.

Abstract: The system includes an active unit, such as a detector unit, which has a processor, a network port for connection to a central control unit, and an optical data input port. The processor is arranged to enable the optical data input port on receipt of an enable signal received by the active unit from the central control unit via a network.

Abstract: The system includes an active unit, such as a detector unit, which has a processor, a network port for connection to a central control unit, and an optical data input port. The processor is arranged to enable the optical data input port on receipt of an enable signal received by the active unit from the central control unit via a network.

Abstract: An isolator circuit (25) for a unit of a safety system (10) includes a power control line (14) connectable to a first loop of a safety system and a power connection (16) connectable to a second loop of the safety system. A switch (26) is connected to the power control line (14), and the switch has a closed configuration and an open configuration. A controller (28) controls the configuration of the switch (26). If a voltage across the circuit (10) from the power connection (16) to the power control line (14) falls below a predetermined level, the controller (28) opens the switch (26), thereby causing a disconnection to occur in the first loop.

Abstract: The system includes an active unit, such as a detector unit, which has a processor, a network port for connection to a central control unit, and an optical data input port. The processor is arranged to enable the optical data input port on receipt of an enable signal received by the active unit from the central control unit via a network.

Abstract: The system includes an active unit, such as a detector unit, which has a processor, a network port for connection to a central control unit, and an optical data input port. The processor is arranged to enable the optical data input port on receipt of an enable signal received by the active unit from the central control unit via a network.

Abstract: The system includes an active unit, such as a detector unit, which has a processor, a network port for connection to a central control unit, and an optical data input port. The processor is arranged to enable the optical data input port on receipt of an enable signal received by the active unit from the central control unit via a network.

Abstract: The system includes an active unit, such as a detector unit, which has a processor, a network port for connection to a central control unit, and an optical data input port. The processor is arranged to enable the optical data input port on receipt of an enable signal received by the active unit from the central control unit via a network.

Abstract: An isolator circuit (25) for a unit of a safety system (10) includes a power control line (14) connectable to a first loop of a safety system and a power connection (16) connectable to a second loop of the safety system. A switch (26) is connected to the power control line (14), and the switch has a closed configuration and an open configuration. A controller (28) controls the configuration of the switch (26). If a voltage across the circuit (10) from the power connection (16) to the power control line (14) falls below a predetermined level, the controller (28) opens the switch (26), thereby causing a disconnection to occur in the first loop.

Abstract: An isolator circuit (25) for a unit of a safety system (10) includes a power control line (14) connectable to a first loop of a safety system and a power connection (16) connectable to a second loop of the safety system. A switch (26) is connected to the power control line (14), and the switch has a closed configuration and an open configuration. A controller (28) controls the configuration of the switch (26). If a voltage across the circuit (10) from the power connection (16) to the power control line (14) falls below a predetermined level, the controller (28) opens the switch (26), thereby causing a disconnection to occur in the first loop.

Abstract: A mounting unit (10) for mounting an electrical component (16) to a panel has a first member (12) arranged to engage a first side of said panel and a second member (14) arranged to engage the first member and a second, opposite side of said panel, so as to secure the first and second members to opposite sides of the panel through a hole in the panel. The first and second members define a space for receiving the electrical component. The mounting unit is particularly suitable for mounting the electrical component to a ceiling tile.

Abstract: An isolator circuit (25) for a unit of a safety system (10) includes a power control line (14) connectable to a first loop of a safety system and a power connection (16) connectable to a second loop of the safety system. A switch (26) is connected to the power control line (14), and the switch has a closed configuration and an open configuration. A controller (28) controls the configuration of the switch (26). If a voltage across the circuit (10) from the power connection (16) to the power control line (14) falls below a predetermined level, the controller (28) opens the switch (26), thereby causing a disconnection to occur in the first loop.

Abstract: An isolator circuit (25) for a unit of a safety system (10) includes a power control line (14) connectable to a first loop of a safety system and a power connection (16) connectable to a second loop of the safety system. A switch (26) is connected to the power control line (14), and the switch has a closed configuration and an open configuration. A controller (28) controls the configuration of the switch (26). If a voltage across the circuit (10) from the power connection (16) to the power control line (14) falls below a predetermined level, the controller (28) opens the switch (26), thereby causing a disconnection to occur in the first loop.

Abstract: A mounting unit (10) for mounting an electrical component (16) to a panel has a first member (12) arranged to engage a first side of said panel and a second member (14) arranged to engage the first member and a second, opposite side of said panel, so as to secure the first and second members to opposite sides of the panel through a hole in the panel. The first and second members define a space for receiving the electrical component. The mounting unit is particularly suitable for mounting the electrical component to a ceiling tile.

Abstract: The system includes an active unit, such as a detector unit, which has a processor, a network port for connection to a central control unit, and an optical data input port. The processor is arranged to enable the optical data input port on receipt of an enable signal received by the active unit from the central control unit via a network.

Abstract: A particulate detector (10) comprises a radiation source (12) arranged to emit radiation in at least first and second predetermined wavebands towards a sampling region (18) suspected of containing particulates, and a detection element (14), shielded from the radiation source (12), and arranged to detect radiation from the sampling region (18) at least first and second instances. The radiation source (12) is such that the emissions in the wavebands temporarily overlap. The detector is such that, at the instances at which the radiation is detected, the relative contributions from the emissions in each predetermined waveband are distinguishable, thereby allowing characteristics of the particulates to be determined. The radiation source (12) may comprise a light emitting diode (24).

Abstract: A method and apparatus of identifying a plurality of devices connected along a common communications link is disclosed. A control station scans the devices by sending a succession of interrogation signals along the communication link, the interrogation signals including representation of the identification numbers of the devices. A first scan is carried out with interrogation signals identifying a first level of the range of identification numbers, and each device is programmed to generate, and to send to the control station, a response signal that includes its complete identification number and a checksum, upon receipt of a scan signal applicable thereto. Successive scans are carried out by the control station, adding the next higher level or the range of identification numbers, wherein upon completion of the scan that does not give rise to valid responses, the previously-paused scan is resumed.

Abstract: A detector comprises a detector base and a sensor, first and second resistors connected in series, a DC voltage source (Vref) connected to the resistors, and means for monitoring the voltage at the midpoint of a potential divider constituted by the series-connected resistors. The first and second resistors are rated so that the midpoint voltage is indicative of the date of manufacture of the sensor.