GB495339A - Improvements in or relating to electrical frequency sensitive devices of the type suitable for automatic tuning devices for radio receivers - Google Patents

Abstract

495,339. Automatic tuning correction. GENERAL ELECTRIC CO., Ltd., and WELLS, G. M. May 13, 1937, No. 13554. [Class 40 (v)] The frequency discriminator network of an automatic tuning system comprises means for generating two voltages v1, v2 of equal frequency f2 but, whose phase relation alpha varies with departure of f2 from a frequency f1, the output of the discriminator being A + k #v1 v2 where A and k are contacts and #v1 v2 is the average of the product v1 v2 over one complete cycle. In Fig. 2 the coupled circuits 6, 7 ; 10, 9, are tuned to the same frequency (f2), their outputs being applied to a hexode 20 whose anode circuit comprises a resistance 23 across which a control voltage of the desired form A+k #v1 v2 is developed and applied to control frequency f1 to bring f1 and f2 into virtual equality. Frequency f1 is applied across the input 1, 2, and voltages v1 v2 are developed across points A, B and earth respectively. The hexode 20 is so chosen that its average anode current is of the form I=I0+k V1 V2 cos alpha, where V1, V2 are the peak values of v1 and v2. The control voltage may be applied either to vary the bias of a control valve or to a mechanical device such as an electrodynamometer; in the latter case the voltages v1 v2 are applied to a pair of valves in each anode circuit of which is arranged a dynamometer coil. The mechanical resultant is then, according to the Specification, of a form corresponding to A + k #v1 v2. Specifications 332,834, [Class 40 (v)], and 392,567 are referred to.