Patent GB-232218-A (GB)
Title: System for supplying current to vacuum tubes
IPC: H02M1/14
Filed: 1925-04-06
Abstract: 232,218. Gage, E. G. April 8, 1924, [Convention date]. Thermionic amplifiers and detectors.-A steady direct current for the filament of the valve 14, 15 is derived from the alternating-current supply by a system employing two miniature storage batteries, two rectifiers, and a transformer. Current from the a.c. mains 1 through a transformer 2 is fed to the mid-point of a four-cell battery in two sections 5, 6 which are alternately charged by the use of rectifiers 3, 4 of any suitable type connected as shown. The output of this battery charges a two-cell battery 7 and an impedance 8 in the circuit smooths out the ripples. Two adjustable resistances 9, 10 are connected to a coil 11 variably coupled to a coil in the output circuit so that ripples due to local causes may be neutralized. The input and output connections to the batteries 6 - - 7 are made at different points on the end electrodes, as shown in Fig. 2, to separate the current paths as far as possible, or these electrodes may be divided and connected by an impedance, Fig. 3, which may assist in smoothing- out the pulsations. The Specification as open to inspection under Sect. 91 (3) (a) comprised the following :-An alternating-current supply energizes the filament and plate circuits. The filament and plate circuits mav be fed from a motor generator composed of three similar machines on a common shaft all characterized by a sub-audible commutator ripple. Each machine has a two-pole permanent magnet 25 and an armature wound with two coils upon laminated poles 28, 29 and 30, 31 respectively arranged at right angles. Each coil is connected diametrically to its own commutator, which is a continuous ring of high-resistance material such as German silver or high-resistance graphite supported on a disc, preferably of bakelite. The cross-section of the commutator rings mav be varied to modify the wave form of the pulsating current produced. The coils may be connected through the commutator brushes in parallel or series. The generators 21, 22, Fig. 1, furnish a unidirectional current of slightly waved character which may be smoothed out by external impedance if desired. The motor 23 has a laminated armature and field poles which may have a series winding, for use with alternating current. It is stated to operate sparklessly and to be capable, with a transformer, of starting alternating-current motors. The motor generator, consisting of a motor fed with alternating current from a transformer and two generators, is run at a speed of about 112 R.P.M., which yields pulses at the rate of 15 per second. The generator 22 may supply the filament current for a valve 17 and the generator 22 the plate circuits of valves 14, 17. In order that independent connections may be made to the electrodes of the valves an adapter, Fig. 4 (Cancelled) is used having external terminals connected to the usual terminal elements. A rubber cap, Fig. 5 (Cancelled) supplied with the adapter may, for example, be placed upon the grid terminal 18 of the valve 17 so that a sensitive pick-up microphone 19 may be connected to the grid circuit and the set used as an aid to hearing by the deaf. This subject-matter'does not appear in the Specification as accepted.