Abstract: An optical smoke detector (110) is provided that comprises a housing (112) having a base (114) for attaching the detector to a surface and a cover (116) having a side wall (124) and a bottom wall (126) defining the interior of said cover. An optical sensor (131) is provided for generating a signal representative of the detected light and a control circuit (130) is provided for controlling operation of the detector. The control circuit (130) includes a plurality of temperature sensors (D1, D2) for sensing a rise in ambient temperature and generating a signal representative thereof. The temperature sensors (D1, D2) are located above an internal surface of said bottom wall (126) within the housing and are substantially equally spaced. The control circuit (30) is operable to compare said representative signal with a reference signal and generate an alarm signal in dependence thereon.

Abstract: An alarm for detecting smoke comprises a housing (1) having vents (9) for allowing ingress of smoke into the housing. A sensor chamber (22,26) is disposed within the housing and has vents (24a,24b) for allowing ingress of smoke into the sensor chamber and comprises two parts. A diode emitter and diode sensor (25) is mounted within the sensor chamber for sensing light reflected off smoke. An alarm circuit (32), including detection means for detecting smoke sensed by the sensor diode (25), is supported on a printed circuit board (PCB) (29). The PCB is sandwiched between two halves (22 and 26) of the sensor chamber such that an edge (30) thereof extends part-way into said sensor chamber. The sensor is mounted on, near or adjacent to the edge.

Abstract: An optical smoke detector (10) is provided that comprises a light source (154), a light receiver (172), and a control circuit (130) for controlling operation of the detector. The control circuit (130) is configured to apply an unregulated voltage to the to cause it to emit light, to monitor the current through said light source (154) so as to monitor the light emitted by said light source (154); and to monitor the current generated by light received by said light receiver (172) so as to monitor the light received by said light receiver (172). The control circuit (130) generates a ratio signal representative of the ratio of the monitored currents; and compares the ratio signal with a reference value and generate a smoke detection signal in dependence thereon.

Abstract: An alarm for detecting radiation and/or air pollutants such as smoke, carbon monoxide or the like has a control circuit (11) including a microcontroller (12) configured to monitor preselected alarm parameters, and memory means (30, 36, 40) for storing data representing said parameters. The microcontroller (12) has an input/output means (3) connectible both to a preselected voltage level for switching said control circuit between an operational mode and a shutdown mode and to an external processing means for enabling downloading and display of said data.

Abstract: An alarm for detecting radiation and/or pollutants such as smoke, carbon monoxide or the like, the alarm comprises: an alarm circuit (12) including detection means (14) for detecting the radiation and/or pollutants, and an audible alarm (16); a power supply circuit (24) connectable to an external AC power supply for supplying standby power to the alarm circuit (12); and a battery (20) for supplying power to the audible alarm (16) when the alarm is energised. The power supply circuit (20) is configured to supply current to the alarm circuit (12) at a level less than that required to energise the audible alarm (16).

Abstract: An alarm for detecting radiation and/or pollutants such as smoke, carbon monoxide or the like has a housing (500), an alarm circuit (400) including a detector (DET1) for detecting said radiation and/or pollutants, first electrical connections (PL1, PL2) connectable to an external power supply for supplying power to the alarm circuit, and a control circuit (300) responsive to receipt of a preselected number of pulses over a preselected time period to apply a preset control signal to the alarm circuit (400). The alarm circuit (400) is responsive to the preset control signal to reset or test the alarm in dependence on the preset control signal.

Abstract: A rechargeable power supply including voltage protection means through voltage dependent disconnecting means. A rechargeable power supply comprises at least one rechargeable cell connectable to a power source, a Zener diode connected to the at least one cell, and a bipolar transistor or a FET for selectively disconnecting the Zener diode from the cell in order to reduce any discharge of the cell through the voltage protection means. The Zener diode and the transistor are connected together in series and jointly connected across the cell in parallel.

Abstract: An alarm for detecting radiation and/or pollutants such as smoke, carbon monoxide or the like has a housing (500), an alarm circuit (400) including a detector (DET1) for detecting said radiation and/or pollutants, first electrical connections (PL1, PL2) connectable to an external power supply for supplying power to the alarm circuit, and a control circuit (300) responsive to receipt of a preselected number of pulses over a preselected time period to apply a preset control signal to the alarm circuit (400). The alarm circuit (400) is responsive to the preset control signal to reset or test the alarm in dependence on the preset control signal.

Abstract: A rechargeable power supply (10) comprises at least one a rechargeable cell (12) connectable to a power source (14), a Zener diode (20) connected to the at least one cell (12), and a bipolar transistor or FET (22) for selectively disconnecting the Zener diode (20) from the cell (12) thereby to reduce any discharge of the cell (12) through the voltage protection means (20). The Zener diode (20) and the transistor (22) are connected together in series and jointly connected across the cell in parallel.