GB220381A - Improvements in or relating to intervalve transformer systems for use with thermionic valves - Google Patents

Abstract

220,381. Graham, E. A., and Rickets, W. J. May 16, 1923. Thermionic amplifiers. - Intervalve transformers have a condenser inserted between the plate end of the primary coil and the filament end of the secondary coil, the windings being so wound that the electromotive forces due to the electromagnetic and electrostatic couplings respectively produce an additive effect in the secondary circuit. The plate end a<1> of the primary coil a is connected by a ccndenser f to a point b<1> in the secondary circuit situated between the secondary coil b and a leak resistance or choke coil h, the other end b<2> of the coil b being connected to the grid g<1>. The coil a may be wound on a core with its inner end connected to a terminal a<2> and its outer end connected to one plate of the condenser. This may be formed by wrapping over the coil a insulated metal foil in two layers, separated by thin mica or paper. The 'outer plate is connected to the inner end b<1> of the superposed secondary winding b, wound in the same direction as the primary coil a, and the outer end of the winding b is taken to the terminal b<2> connected to the grid g<1>. A biassing- battery may be connected in series with the leak or choke h, and a condenser may be shunted between the terminal a<2> and the filament e<1> of the valve. A loud speaker or telephone mav be connected directly in the plate circuit of the valve, or in series with a condenser t across a coil r, as shown.