Abstract: A circuit for supplying current to a load connected to a pair of output leaves of the circuit has at least one feed circuit, an electronic switch disposed between the feed circuit and the leaves having a transistor with a control electrode and a controlled path, and a control means for operating the electronic switch to disconnect the feed circuit from at least one of the leads when the feed circuit de-energized and to connect the feed circuit to at least one of the leads when the feed circuit is energized. The control means has a further transistor with a controlled path connected in series with the control electrode of the transistor in the electronic switch, and a control electrode connected to the controlled path of the transistor in the electronic switch. The control means further has a resistor connected between the control electrode of the further transistor and one of the load leads.

Abstract: A circuit arrangement comprises two feed circuits which are connectible to a load with mutually opposite polarity. The circuit arrangement avoids mechanical contacts in the load circuit, at least with respect to one feed circuit. This is achieved in that switches, provided for the activation at at least one of the feed circuits, are disposed outside of the output circuit and in that a transistor is disposed between such a feed circuit and the load, this transistor being conductive given an activated feed circuit and being inhibited given a deactivated feed circuit. The circuit arrangement can advantageously be employed in remote feed devices of communications transmission device for the purpose of optionally feeding a remote feed section with a remote feed current or with a fault locating voltage.

Abstract: A circuit for automatically closing a backup remote feed loop upon interruption of the remote feed loop of a remote feed device for supplying electrical users by means of DC series feed has a holding winding and a response winding disposed in a longitudinal arm of a switching relay, the contact of the switching relay being disposed in a cross-arm in series with a choke coil. The relay operates with a very low voltage drop at the holding winding and occupies a relatively small volume. The circuit can be utilized as an auxiliary relay controlled by means of a delay circuit for selectively cutting in and cutting out the response winding of the relay, particularly in remote feed repeaters or regenerators.

Abstract: A circuit closes a remote feed loop of a series-supplied repeater in a communications channel, in the event of an interruption in the transmission line, by means of a relay which senses an interruption in the feed current to close a shunt circuit. The shunt circuit includes a resistance which is initially high, to promote rapid restoration of the communications circuit, and afterwards is lowered to minimize losses and to promote personal safety.