Abstract: The invention provides a method for testing a hazard detector that includes transmitting a test mode switching signal from a test device to the hazard detector, setting the hazard detector to a test mode, transmitting a first test mode confirmation signal from the hazard detector to a central monitoring unit, transmitting a second test mode confirmation signal from the hazard detector to the test device, processing a hazard condition detected by the hazard detector as a test event, transmitting a test result signal from the hazard detector to the central monitoring unit, the hazard detector outputting a test completion signal, and setting the hazard detector to a detection mode. The invention further provides a hazard monitoring system, a hazard detector, and a test device.

Abstract: The invention relates to a method for operating a public address system with a control center to which loudspeakers are connected via a two-wire loop system that is routed via isolator modules. A fault can be located on the loop system if the control center measures the impedance of the loop system successively from isolator module to isolator module and the impedance of the entire loop system, inputs the measured values as target values into an impedance table, periodically measures the impedance of the entire loop system during operation, compares said impedance with the corresponding target value from the impedance table, generates a fault message upon determining a deviation, ascertains the fault location by comparing the measured value with the individual target values in the impedance table, and displays said fault location.

Abstract: An alarm system control center has subscribers connected to it by a two-wire line. The subscribers receive via the two-wire line both a power supply voltage and communication messages in the form of pulse trains impressed on the power supply voltage as voltage modulation. Each subscriber includes a constant current circuit which is connected to the two-wire line and which is used to charge a storage capacitor with a voltage regulator coupled to it. In order to reduce communication errors, a transformer is provided to reduce power supply voltage to an internal value which is lower than the than the power supply voltage at least by the voltage swing of the pulses of the communication messages on the two-wire line.

Abstract: The invention relates to a method for operating a public address system with a control center to which loudspeakers are connected via a two-wire loop system that is routed via isolator modules. A fault can be located on the loop system if the control center measures the impedance of the loop system successively from isolator module to isolator module and the impedance of the entire loop system, inputs the measured values as target values into an impedance table, periodically measures the impedance of the entire loop system during operation and compares said impedance with the corresponding target value from the impedance table, generates a fault message upon determining a deviation, and ascertains the fault location by comparing the measured value with the individual target values in the impedance table and displays said fault location.

Abstract: A hazard indicator including a power-saving control circuit having a transistor with a collector connected via a resistor to the output of the signal processing circuit. In operation, the transistor delivers the clocked control signal for the semiconductor switch as a function of the current-proportional voltage applied to the base of the transistor.

Abstract: An alarm system control center has subscribers connected to it by a two-wire line. The subscribers receive via the two-wire line both a power supply voltage and communication messages in the form of pulse trains impressed on the power supply voltage as voltage modulation. Each subscriber includes a constant current circuit which is connected to the two-wire line and which is used to charge a storage capacitor with a voltage regulator coupled to it. In order to reduce communication errors, a transformer is provided to reduce power supply voltage to an internal value which is lower than the than the power supply voltage at least by the voltage swing of the pulses of the communication messages on the two-wire line.

Abstract: A building control or danger warning system includes a two-core circular bus for voltage supply and for communication with bus user circuits connected to the cores of the circular bus. The bus user circuits are looped-into the circular bus via FET (field effect transistor) polarity-reversal protection bridges, thereby simplifying connection of the bus user circuits to the circular bus. A bus user circuit is located between d.c. connection terminals and connected in parallel with two protection bridges. The bus user circuit measures the voltage conditions and polarity of the a.c. voltage input terminals of the bridges. According to the results of the measurement, the bus is relayed to the subsequent bus user circuit.

Abstract: A hazard indicator including a power-saving control circuit having a transistor with a collector connected via a resistor to the output of the signal processing circuit. In operation, the transistor delivers the clocked control signal for the semiconductor switch as a function of the current-proportional voltage applied to the base of the transistor.

Abstract: A building control or danger warning system includes a two-core circular bus for voltage supply and for communication with bus user circuits connected to the cores of the circular bus. The bus user circuits are looped-into the circular bus via FET (field effect transistor) polarity-reversal protection bridges, thereby simplifying connection of the bus user circuits to the circular bus. A bus user circuit is located between d.c. connection terminals and connected in parallel with two protection bridges. The bus user circuit measures the voltage conditions and polarity of the a.c. voltage input terminals of the bridges. According to the results of the measurement, the bus is relayed to the subsequent bus user circuit.

Abstract: The sensitivity of scattered-light fire detectors for small particles can be increased substantially when blue light is introduced into the measuring volume in addition to an infrared radiation and the scattered radiation produced by the particles is measured and evaluated separately from each other in the infrared and blue region both in the forward scattering region as well as in the backward scattering region. This can be realized by a fire detector that includes two transmitter LEDs (2.1a, 2.1b) and two photodetectors (2.2a, 2.2b), with these components being arranged such that the photodetectors receive both the forward scattered radiations as well as the backward scattered radiations of the longer and shorter wavelengths separately from each other. A multi-channel evaluation circuit is provided downstream of the photodetectors.

Abstract: The sensitivity of scattered-light fire detectors for small particles can be increased substantially when blue light is introduced into the measuring volume in addition to an infrared radiation and the scattered radiation produced by the particles is measured and evaluated separately from each other in the infrared and blue region both in the forward scattering region as well as in the backward scattering region. This can be realized by a fire detector that includes two transmitter LEDs (2.1a, 2.1b) and two photodetectors (2.2a, 2.2b), with these components being arranged such that the photodetectors receive both the forward scattered radiations as well as the backward scattered radiations of the longer and shorter wavelengths separately from each other. A multi-channel evaluation circuit is provided downstream of the photodetectors.

Abstract: The sensitivity of scattered-light fire detectors for small particles can be increased substantially when blue light is introduced into the measuring volume in addition to an infrared radiation and the scattered radiation produced by the particles is measured and evaluated separately from each other in the infrared and blue region both in the forward scattering region as well as in the backward scattering region. This can be realized by a fire detector that includes two transmitter LEDs (2.1a, 2.1b) and two photodetectors (2.2a, 2.2b), with these components being arranged such that the photodetectors receive both the forward scattered radiations as well as the backward scattered radiations of the longer and shorter wavelengths separately from each other. A multi-channel evaluation circuit is provided downstream of the photodetectors.

Abstract: A method for contacting printed conductors terminating at the edge of a circuit board with printed conductors of a MID component includes: on a panel which includes the circuit board, producing the printed conductors of the circuit board in a layout in which the printed conductors are extended past a partition line which defines the edge of the circuit board; providing the panel with through holes along the partition line in the region of the printed conductors; electroplating through the through holes; isolating the circuit board from the panel; and positioning the circuit board in relation to the MID component and soldering the printed conductors of the circuit board to the printed conductors of the MID component. Rear electrical contacting areas are provided on a back side of the panel near the partition line, and the printed conductors are connected to the rear electrical contacting areas via the through holes.

Abstract: A method for signaling an escape route in a building with emergency warning units arranged in a distributed way can be realized such that the emergency warning units are equipped with luminous means that in the event of an emergency can be activated by a central emergency warning system sequentially in the manner of a running light that designates the direction of the escape route leading away from a hazard site. An emergency warning unit suitable for this purpose may include two LEDs configured as arrows facing in opposite directions, of which either can be switched into a blinking mode by the central emergency warning system in accordance with the emergency conditions.

Abstract: An electrical plug connector for information technology purposes, in particular a RJ45 connector, is parallel with several contacts that are arranged in contact pairs. The contacts comprise each a terminal area, a contact section for the engagement with contacts of another electrical plug connector and a line section that connects the terminal area with the contact section, wherein the contact sections are arranged in parallel planes. All line sections run at least partially parallel to each other and in a joint plane. The line sections and the contact sections of each contact are arranged at an angle to each other and all contacts are bent in the same direction in the transition region between line section and contact section. The transition regions of contacts of different contact pairs have different progressions between the line section and contact section in the respective parallel planes.

Abstract: An electrical plug connector for information technology purposes, in particular a RJ45 connector, is parallel with several contacts that are arranged in contact pairs. The contacts comprise each a terminal area, a contact section for the engagement with contacts of another electrical plug connector and a line section that connects the terminal area with the contact section, wherein the contact sections are arranged in parallel planes. All line sections run at least partially parallel to each other and in a joint plane. The line sections and the contact sections of each contact are arranged at an angle to each other and all contacts are bent in the same direction in the transition region between line section and contact section. The transition regions of contacts of different contact pairs have different progressions between the line section and contact section in the respective parallel planes.