Abstract: On the moving body, the apparatus comprises an active transponder, and on the track it comprises a passive responder. The transponder has an LF transmitter and an MF transmitter which, during displacement of the moving body, transmit to a zone through which the responder passes during said displacement. The responder has an LF receiver circuit and an MF receiver circuit having tuned radiating circuits that are associated so that an LF signal induced in the LF circuit causes the MF radiating circuit of the responder to be closed at the LF rate. The transponder responds to disturbances in the MF transmitter caused by the MF circuit of the responder being closed. The MF circuit of the responder includes two units having respective tuned radiating circuits that are strongly coupled together. Each is connected to a respective logic unit which, when excited, delivers a digital message causing the MF radiating circuit to be closed only for bits of a determined value in the digital message.

Abstract: The safety control device with digital input and analog output, is intended to deliver a mean output power above a specified threshold when two binary input sequences which are complementary or in phase opposition are applied to the input and an output power appreciably below the threshold in all other cases. It comprises a primary voltage source (18) supplying a cascade of several modules (16.sub.1 , . . . , 16.sub.k) each having an AC converter bridge and a rectifier, each branch of the AC converter bridge being controlled by one of the sequences.

Abstract: (a) A cooling installation working through a change in Phase.(b) An installation wherein the chamber is connected to an expansion vessel through a valve calibrated at a determined opening pressure depending on the nature of the heat-carrier fluid and on the maximal temperature desired within the chamber and/or on the element to be cooled, said expansion vessel carrying a means for draining off the contents of the expansion vessel.

Abstract: A control for a variable reluctance motor, comprising a d.c. source, a power control circuit, and a command circuit, in which the power control circuit comprises main control switches in series with the windings of the motor to form terminal branches, the terminal branches being connected in groups of two in series between the two poles of the source in such a way that two complementary windings are never in series, as well as free-wheel branches to close the circuit of each winding when at most one main control switch in a branch is conducting, and a turn-off circuit for the main control switches, and including at least one current detector to register the current in the windings; each free-wheel branch includes a coil and a diode, the diode polarized to oppose normal current flow through its associated main control switch.

Abstract: This invention is relative at a position coder used with a variable reluctance machine to control the commutations of the stator windings on this machine, said coder being characterized by having magnetic circuits for its rotor and its stator which are identical to those on the variable reluctance machine and which are set in an identical manner.