Local to central fire alarm coupling unit - allows special practice signal to be transmitted when coupler circuit door is open

摘要

An opt-electronic coupling unit is incorporated in a simple coupling equipment for use in coupling a local fire alarm transducer or system to a central system. This permits the transmission of a special practice signal when the coupler door is open and avoids a telephone call to the central system when a practice alarm is to be triggered. The coupling circuit consists of a.l.e.d. and photosensitive transistor, which link the incoming local line (HAL) to the outgoing central alarm line (HML) without electrical connection. A switch (TK) in the coupling unit door switches the outgoing line to another circuit which can be prompted, in a practice run, to send a signal of its won characteristic frequency to the central alarm. The real case circuit is reconstituted when the door is closed.