A television signal transmission system is improved to be able to transmit a video signal having a frequency band wider than existing transmission frequency bands while maintaining compatibility with existing television systems. On the sending side, a wide-band luminance signal is frequency-shifted and inserted into a vacant frequency spectrum of a television signal in the existing television systems before transmission.

A speed control circuit for a series field direct current motor. The circuit includes a reed relay that has a movable contact responsive to the current flow through the field and a resistance in a shunt circuit with the field. The reed relay through a transistor and a contactor causes the shunt circuit to be interrupted when the current flow through the motor increases above the predetermined value. The reed relay has a pair of coil windings arranged so that one of the windings generates a magne...

An improved visual field testing device is disclosed. The device is a modification of an automatic Goldmann-type perimeter device which permits operation by the physician or technician.

A dilator for application in the medical field, comprises a hollow body made of an elastically deformable material and defining a cavity. Ducts hydropneumatically connect the cavity of the body to a source of pressurized fluid, valves controlling the hydropneumatical communication between the cavity and the source of pressure fluid and the outside. The body expands when positioned in situ and when in hydropneumatic communication with the source of pressurized fluid and being thereby effective to...

A vertical field effect transistor (10) includes a relatively wide bandgap, lowly doped active layer (18) epitaxially grown on, and substantially lattice matched to, an underlying semiconductor body portion (13). A mesa (20) of lower bandgap material is epitaxially grown on and substantially lattice matched to the active layer. A source electrode (22) is formed on a bottom major surface (34) of the semiconductor body portion, a drain electrode (24) is formed on the top of the mesa, and a pair of...

Monitoring system particularly for detecting the presence of moving persons in a monitored area. This system comprises two detection stages 2 and 22, two processing stages 3 and 23 and a selective switching-on stage 4 which the two groups of stages 2, 22 and 3, 23 have in common. Each one of the detection stages 2 and 22, which comprise cameras 7 and 27, respectively, send field signals to the associated processing stages, these signals corresponding with the observed images. Each processing sta...

A magnet assembly for a permanent magnet direct current electric motor has two arcuate members positioned in a cylindrical frame by a pair of spring clips which maintain the position of the arcuate member within the frame prior to magnetization of the arcuate members. Each spring clip has circumferentially extending primary spring arms, radially extending secondary spring arms and an arcuate base portion to which the secondary spring arms are integral with. The primary spring arms bear against r...

A sensing element for measuring atmospheric electrical field comprising a fixed detection electrode and a rotating modulator. Between the detection electrode and the rotating modulator there is interposed a fixed apertured screen, conductive of electricity and connected to the sensing element mass. The screen has a peripheral portion protruding relative to the modulator. The sensing element measures both slow field variations and abrupt field variations.

A steric field-flow fractionation system including a flow channel adapted for use with a carrier stream of fluid having particles suspended therein and a force field disposed across the flow channel to cause migration of the particles to a restraining wall, thereby forming layers of particles at the restraining wall. The strength of the force field is adjusted sufficiently high to maintain the particles of a given class at the restraining wall such that particle distance from the wall is a funct...

In magneto-telluric geophysical exploration, the earth's electric telluric field in two orthogonal directions is determined. Electrodes are positioned on the earth's surface so that measured potentials between adjacent electrodes measures the earth's telluric field in known directions. These measurements are converted to signals representing the earth's telluric field in two specified orthogonal directions. The measurements are made between electrodes spaced along a cable which is laid on the oc...