Patent GB-190208172-A (GB)
Title: Improvements in and relating to Apparatus for the Production of Electrical Oscillations of Requisite Amplitude and Frequency.
Inventor: MANDERS HORACE
Filed: 1902-04-08
Granted: 1903-06-08
Abstract: 8172. Manders, H., and Sharman, A. W. April 8. Condensers; induction coils; spark-gap apparatus; switches.-Relates to the production of electric oscillations of variable frequency and amplitude. The apparatus includes condensers of variable capacity, variable inductances or impedances, resonators, and special spark gaps. The condensers are preferably formed of thin metallic plates separated by thin plates of insulating-material, such as mica, and may be immersed in insulating-oil. In the construction shown in Fig. 1, the capacity is varied by constructing the condenser C, C<1> in sections connected to the contacts D, D<1> of a switch, the movable arm F, F<1> of which is adapted to connect up one or more of the sections with the induction coil or other highpotential source I. Fig. 3 shows another construction of the condenser, in which a hemi-cylinder B<1> forms one electrode and the curved plate B the other. Or a cylinder is arranged to slide within an outer concentric cylinder. Fig. 4 shows another form, one of the electrodes A consisting of metal foil or the like adapted to be rolled on a spindle B, D being the fixed electrode. According to the Provisional Specification, to avoid danger from the wire for tapping-off oscillations from a condenser plate being by that means connected to a source of high potential, a second condenser is used, one plate of which is connected to either plate of the principal condenser, and from the other plate of which the oscillations are derived ; or two extra plates are placed in proximity to the plates of the condenser, and the impedances described below placed in the circuit joining the extra plates instead of that of the condenser. Instead of varying the capacity, the impedance of the discharge circuit may be varied. The movable impedance may consist of one or more solenoids, the convolutions of which can be brought closer together or wider apart to vary the self-induction Or, as shown in Fig. 10, it may consist of a coil S having two smaller coils B, B<1> in series. The bobbins for the smaller coils are mounted on a rod A, and may be slid within the coil S. In another arrangement, a flat helix may be employed, and the inductance varied by winding up or relaxing the coil ; or contact may be made at different points of the helix. Fig. 11 shows another arrangement. The inner coil S' is arranged to rotate so as to lie more or less inclined to the plane of the coil S. In order to obtain oscillations of a greater amplitude, a step-up transformer is provided, the secondary winding being formed, as shown in Fig. 13, in two coils, one within and the other without the primary. The windings may be interconnected, or so connected to earth as to give either two potential maxima or a single maximum at one end. The amplitude of the oscillation may also be increased by connecting the secondary to a correctly-tuned circuit or resonating-conductor. The resonating-conductor may consist of a helix of wire &c. wound as shown in Fig. 17, with increasing insulating-space between the turns. The secondary may be connected to one end of the helix, in the case of an uniformly-wound helix, or to the middle point. Similar resonators may be connected to each condenser plate through a solenoid tuned by cutting in or out some of the turns by means of contact-arms arranged like a pair of scissors. The spark gap, Fig. 6, is formed of a combination of points and plates and enclosed in a vessel or vessels,in which the air may be compressed and which may be provided with soda-lime or the like to absorb nitrogen compounds produced by the discharge. The spark gaps may have the compound terminals as shown in Fig. 9, in which a point on one faces a plate on the other. The Provisional Specification states that the apparatus is fitted in a cabinet having one compartment for the accumulators, a second for the coil, and the third for the condensers, resonators, &c. and a controlling- switchboard.