| 摘要 |
The invention relates to a circuit arrangement for a signal transmitting device (NRM) which is connected via a signal line (a, b) to a signal receiver (VSt, AI, AII). Once an alarm contact (nrk) has been actuated, it automatically transmits signals by closing or opening a signal circuit via the signal line (a, b). The signal transmitting device (NRM) is supplied via the signal line (a, b) with electric power, for which purpose the input side (wI, wII, Ts1, Ts2) of a DC voltage converter (Tr1, Ts1, Ts2, D9, D10, D11, St) is looped into the signal circuit. The opening and short-time closure of the signal circuit is effected through conducting or non-conducting control of the chopper switching means (Ts1, Ts2) of the DC voltage converter. The invention can be used advantageously as an emergency call detector (NRM) in an emergency call system, where, once the alarm contact (nrk) has been actuated, the emergency call detector (NRM) automatically dials the telephone number of an emergency service station. <IMAGE>
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