Terminal block for telecommunications and data systems engineering

摘要

Remote disconnecting devices are needed for being able to determine at the point of interconnection of the telephone network of one operator with the network of another operator in which part of the coupled networks a fault has occurred, that is to say to separate the networks from one another with respect to direct voltage for measuring purposes.
Remote disconnecting devices based on TRIACS and MOS-FETS are known, where a uniform switching threshold is used. If controlled silicon rectifiers are used as electronic switches, the switches are connected to one another by a switching element in order to be able to transmit dialling pulses from the telephone to the exchange and to use switches with insensitive control terminals.
According to the invention, the use of self-inhibiting MOS-FETs of the enrichment type provides for a high turn-on threshold and a low turn-off threshold so that the usual measuring method of dropping the voltage can be used. It is also possible to make the turn-on threshold dependent on the polarity of the voltage.