Abstract: A remote alarm system that includes short range personal portable transmitter devices, which can be manually actuated in order to transmit a predetermined warning signal, and a plurality of fixed receiver devices disposed at suitable locations on a site to be protected, the said receiver devices being suitable for receiving the warning signal transmitted by any one of the portable devices located within range and transmitting the warning thus detected to security personnel.This system is more especially intended for the users of public places and public transport such as, for example, the underground railway.

Abstract: The system includes a basic recorder module where a delay element is followed by a solid state buffer memory, digital interface circuits for transferring the recorded data, processing means, a printer and/or magnetic memory unit, a detachable programming terminal for the dialogue with the recorder and its programming, as well as a separate power supply for the working part, so that the latter is only supplied in the recording mode or during a connection of the programming terminal.

Abstract: A stationary device for sensing the rotational speed of electric motors, comprising an impedance bridge circuit, the motor being inserted into one branch of the bridge in series with a resistive element, and a voltage proportional to the rotational speed being derived across a diagonal of the bridge, the resistive element being a winding wound directly on to the motor, in order to make it isothermic, and insensitive to the magnetic field of said motor by a form of winding of the "two wires in hand" type.