| 摘要 |
A gas and smoke alarm for operation in commercially available plug sockets connected to the public mains, which, in addition to the alarm siren which is located in the apparatus, has the capability to operate an external, and possibly physically separated, siren. A protection circuit prevents the apparatus being damaged if the electrical supply lead or the external siren itself is short-circuited. If this occurs, a built-in light-emitting diode illuminates and indicates the defect. In the event of a power failure, the operation of the apparatus continues to be guaranteed for a short time by the built-in accumulator or the battery. If an accumulator is used, this is charged during normal mains operation. In order that the accumulator or the battery does not discharge itself after the apparatus has been removed from the mains, a switching device is operated when the apparatus is pulled out of the mains socket, which switching device isolates the electrical connection to the accumulator or to the battery. In this way, relatively long storage of the apparatus is also possible without the accumulator or battery discharging. |
