Abstract:
A multi-channel rotary joint, designed to couple a stationary and a rotary component of a radar system to each other, comprises a main channel centered on the axis of rotation and a plurality of axially spaced ancillary channels coaxially surrounding the main channel. Each ancillary channel is formed by two capacitively coupled coplanar rings respectively carried on a stationary and on a rotatable dielectric sleeve centered on the axis, each ring comprising two concentric annular conductor strips on the inner and the outer sleeve surface. The inner and outer conductor strips of each ring are interrupted by small equispaced gaps which are relatively offset to form overlapping segments of two concentric transmission lines which are electrically continuous except at one point at which the line is coupled to a respective balun also formed by arcuate conductor strips.
Abstract:
The present invention relates to a device for starting and supplying a fluorescent tube, including a resonant system connected to the tube and to a rectified supply circuit with a switch in series. A first detector controls the switch to turn off when the current provided by the supply exceeds a determined threshold; and a second detector controls the switch to turn on for each transition through zero of the voltage on a node of the resonant system and for each transition through a minimum of this voltage.
Abstract:
An error amplifier providing an analog error signal, including an operational amplifier, an output terminal of which controls an active load of discharge of a resistive and capacitive network supplied by a reference current source, and circuitry for copying the reference current in an input resistor, a terminal of which receives a measurement signal and the other terminal of which is connected to a non-inverting input of the operational amplifier, the error signal being available across the resistive and capacitive network.
Abstract:
A voltage converter including a circuit for controlling a switch for providing current to a primary winding of a transformer with inverted phase points, a secondary winding of which is associated with a capacitor for providing a regulated D.C. output voltage and an auxiliary winding of which provides a supply voltage of the control circuit. The average value of the voltage across the auxiliary winding close to the end of its demagnetization periods.
Abstract:
A device for providing a high d.c. voltage supply and a low d.c. voltage supply. The device includes, in parallel, a first diode connected in series with a capacitor, a rectifier having a polarity opposite to that of the first diode, and a breakover voltage limiter. The terminals of the low d.c. voltage source correspond to the terminals of the capacitor.
Abstract:
The invention concerns a circuit for detecting an overload in a load supplied by a switched-mode power supply, comprising: a first comparator of a first voltage based on the supply voltage of the load relative to a first threshold, supplying a regulating signal to a pulse generator controlling the switched-mode power supply; a second comparator of a second voltage relative to a second threshold, supplying a signal indicating the presence of an overload; and means for automatically controlling said second voltage by a third threshold lower than the second and higher than the first, and for deactivating the second comparator as long as said automatic control is maintained.
Abstract:
The invention concerns a control circuit (20) of a switch (6) chopping a voltage supply of a primary winding of a power converter transformer, comprising means (45) for detecting the current in the switch in closed state after a predetermined time following each closure of said switch, and a comparator (40) of said current relative to a threshold (Ilim), the result of said comparator being taken into account for a predetermined time interval close to the beginning of a closing cycle of said chopping switch.
Abstract:
A lead with an increased impedance for an active implantable medical device, in particular for a pacemaker. The lead comprises a cylindrical body (14) presenting at its distal end a contact surface (30) for making contact with the endocardium, which is electrically insulated, and a stimulation electrode (16), which is electrically conducting and which is connected to a conductor of the lead. The electrode (16) has at least one active element (22), for example, a plurality of protuberances (22), each one presenting at least an exposed extremity tip (26) having a hemispherical area, making a ledge compared to the contact surface (i.e., protruding) therefrom. The active element presents on at least a part of its exposed extremity to be placed in contact with the endocardium a radius of curvature less than 0.5 mm, more preferably less than or equal to 0.3 mm. With a microporous vitreous carbon as the material of the protuberances, one can at least increase the contact impedance of the lead at the heart/electrode interface to 800 Ohm, preferably up to approximately 1000 Ohm. An annular flat form or disc-shaped active element also can be used as an alternative to the protuberance(s).
Abstract:
A circuit and method for controlling the speed of a universal motor driven by an AC source is disclosed. The method includes the steps of measuring a value of a temporal property of a current through the motor and determining a speed of rotation of the universal motor using the temporal property. The method for controlling the speed of the universal motor further includes comparing the determined speed of rotation with a desired speed of rotation and adjusting the current through the motor so that the speed of the motor approaches the desired speed of rotation.
Abstract:
The equipment consists, on the one hand, of a metallic adaptor (2) having an upstream end (10) which can be connected to the syringe and a downstream end (9) which can be connected to a disposable cannula (1), the said cannula (1) defining at least two channels (5, 6) for distribution of fluid, and the said adaptor (2) comprising a corresponding number of supply channels (18, 19) which can be brought into correspon-dence, for communication of fluid, with the said distri-bution channels (5, 6).According to the invention, the cannula (1) is made of moulded plastic material, the distribution channels (5, 6) are of constant cross-section at least over almost the whole of their length, and tubular sleeves (25, 26), connected to the said supply channels (18, 19), project from the downstream end face (37) of the said adaptor (2), the relative position and the dimensions of the said tubular sleeves (25, 26) being such that they are designed to be received, each one, in the upstream end of a distribution channel (5, 6).