Abstract: A multi-wavelength light emitting and receiving apparatus for monitoring connections by optical fibers comprising a case, an emission section, a reception section, a keyboard for selecting operating modes and measurement scales, a display arrangement, a processing unit including a microprocessor connected to the emission section, the reception section, the keyboard and the display arrangement, and a feed. The emission and reception sections are mounted in a drawer provided with a connector that can be inserted into a complementary connector provided in the case, this latter containing the keyboard, the display arrangement, the processing unit, and the feed.

Abstract: A Hall-effect current clamp, in which the constant-current generator (13) supplying the Hall-effect cell (8) comprises an operational amplifier (15) which has an internal-voltage reference (17) and which pilots a transistor (Q1) mounted in emitter follower in series with the cell (8), such that the current which traverses it is on the order of 1 mA. At the output of the measurement amplifier (14) of the clamp, a dividing bridge (P1,R5) whose intermediate lead is connected to the inverting (-) input of the amplifier (14) permits obtaining a supplementary amplification of the output signal of the clamp at the price of a low current consumption. Thus, the total current consumption of the clamp is maintained at a very low level, thereby providing a considerable increase in the life span of the batteries (9) used to supply the clamp.

Abstract: A magnetic flywheel for a manually-driven magneto megohmmeter with step variable voltage comprising a rotor formed by a ring of magnetic material carrying permanent magnets, and a stator, disposed inwardly of the rotor and formed by an assembly of magnetic circuits each having a C-shape with a coil wound around the central portion thereof and with two pole surfaces at the ends. In order to reduce the starting torque, the number of pairs of permanent magnets is one less than the number of magnetic circuits, and the angular distance between the pole surfaces of one magnetic circuit is equal to the angular distance between two adjacent permanent magnets. Also, the arc length of each pole surface of a magnetic circuit is substantially equal to half the angular distance between two adjacent permanent magnets.

Abstract: Device for transmitting an alternating analog signal from a sensor to a measurement room remote from the sensor, comprising a preamplifier situated in the vicinity of the sensor for preamplifying the output signal thereof, a line with two conductors, a measuring circuit receiving through the line the preamplified signal, a circuit for supplying power to the preamplifier, a circuit for checking the proper operation of the device and a circuit for modifying the gain of the preamplifier. The line transmits simultaneously the DC supply current, a checking signal in the form of an alternating voltage, a gain modification signal by modifying the level of the DC supply current and the measuring signal by a charge variation generated by an electric charge generator inserted between the preamplifier and the line. A DC current absorber is inserted between the output of the charge generator and the supply terminal of the preamplifier.

Abstract: Electromagnetic relay comprising resilient U-shaped tongues having each a pair of arms resiliently engaging fixed contact studs for electrically interconnecting them, and a movable control member adapted to move one of the arms of each tongue away from the corresponding contact stud, for breaking the electric connection. This relay further comprises a second control member movable in a direction opposite to that of the first control member and adapted to co-operate with the first control member for clamping the U-shaped tongue and move the two arms thereof away from the relevant contact studs.