A circuit for protecting electronic devices which are fed from a source of dc voltage and to which a subscriber's line (ASL) is connected. In order to limit the current in the event of an overload on the subscriber's line (ASL), a MOSFET (T1) is provided as current-limiting component. The MOSFET (T1) is disconnected and re-connected periodically by means of a relaxation generator (K) when the MOSFET is in its current-limiting condition. Upon the normal operation of the circuit, the relaxation generator (K) does not operate. By proper dimensioning thereof, the time for which the MOSFET (T1) is blocked can be roughly adjusted as compared with the time in which it acts as current limiter. In this way, too great a heating of the MOSFET (T1) is avoided. |