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 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 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: 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: 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 scattered light fire detector and a method for evaluating scattering signals of a fire detector are disclosed. The microprocessor-based scattered light fire detector measures the scattering signals at two scattering angles and determines an alarm threshold. An alarm value is determined as a function of the ratio of the scattering signals and compared with the determined alarm threshold. The fire detector can be used with mixed fires without prior calibration. Fraudulent measurement values arising, for example, from water vapor can be stored in a memory.

Abstract: A danger alarm system includes a plurality of detectors, each of which having a microprocessor, a current drain controllable by the microprocessor for data exchange with a central station, an address register, and a nonvolatile memory for containing an individual binary serial number.

Abstract: A contact element suitable for SMD printed circuit boards is made of a flexible blank of sheet metal of approximate C-shaped cross-sectional configuration, with dimensions of a DIL package for SMD integrated circuits. The contact element is provided with bent terminals which are soldered onto respective bonding pads upon the circuit board while the top surface of the contact element is provided for contacting by a resilient external countercontact.

Abstract: A fire detector includes a scattered light detector unit and an ionization detector unit which are arranged upon a common base at each side of the center axis of a compartment defined by the base and a peripheral wall extending from the base. The scattered light detector includes a light source and a receiver, with their principal axes intersecting in a point of intersection which is positioned at one side of the center axis of the compartment and thus extends eccentric to the center axis. The ionization detector unit includes a holder for a preparation to be ionized, with the holder being arranged at the other side of the center axis. Suitably, a heat detector is further provided in the center axis.

Abstract: An ionization fire detector of the type including a measuring chamber and a reference chamber having a common electrode which is connected to the gate terminal of a field-effect transistor by a profile piece of conductive caoutchouc having one end contacting the gate terminal and another end contacting the common electrode.