GB424423A - Improvements in hand-operated indicators for facilitating identification of wireless transmitting stations - Google Patents

Abstract

424,423. Calculating - apparatus. RICHARDSON, E., 17, Boscombe Road, Shepherd's Bush, London. Aug. 16, 1933, No. 22923. [Class 106 (i)] A hand-operated device for use in calculators relating to the tuning of wireless receivers comprises a base member having a series of scales b<1> divided into different numbers of parts, a disc a rotatable on the base member and provided with slots a<2> and " zones " a<1>, and a masking member rotatable above the disc and having a sector-shaped slot to expose any one zone. The tuning range of a wireless set is divided into a number of zones, the beginning and end of each zone being the wavelength of an easily-identified station. Each zone is divided again into " channels " spaced apart an equal number of wavelengths, the spacing being such that a different station could occupy each channel. The degrees of movement of the tuning dial in passing from one end of a zone to the other are determined and, assuming the same movement for each unit change of wavelength within the zone, the movement necessary to tune to any channel within the zone can be calculated by simple proportion. The device described for assisting this calculation comprises a disc a divided into zones I-VIII, each zone being marked with the numbers of the channels 5-103 and with the easily-identified stations. The disc is rotatable over a base plate having a series of scales b<1> divided into 10, 11, 12-39 equal parts. By rotating the disc, any scale can be brought beneath a slot a<2> in each zone, so that the zone can be divided into the number of equal parts corresponding to the tuning-dial movement in passing from one end of the zone to the other. The tuning-dial movement necessary to pass to any of the numbered channels within the zone is then indicated by the base-scale division adjacent the channel number. The disc a is covered by another disc having a sector-shaped opening so that all but the zone under consideration is obscured. A rotatable disc a may be provided on both sides of the base plate, scales being formed on each side one side being used for long wavelengths and the other for medium wavelengths.