Device for the remote adjustment of an inaccessible element

A device for the remote adjustment of a switchable network equipping an unattended station on a transmission line, from a terminal station on this line, comprising at the unattended station:

• a switch having several contact elements, connected to said switchable network for operating the same;
• a direct current motor having two possible rotating directions, for actuating said switch,
• a circuit having a first input for a first remote control frequency and a second input for a second remote control frequency, said frequencies being emitted from the terminal station, said circuit having two outputs connected respectively to a first and a second terminal of said motor, said circuit operating said motor according to the presence or absence of said remote control frequencies at said inputs,
• an oscillator permanently emitting a third frequency, and
• means for sending back to the terminal station said third frequency, said means including an attenuation network having two attenuation coefficients and means controlling said attenuation network and connected to said switch for enabling said attenuation network to present a first attenuation coefficient when said switch is on a contact element and a second attenuation coefficient when said switch is between two contact elements.