GB380325A - Improvements relating to the control of high frequency tuning apparatus - Google Patents

Abstract

380,325. Adjusting wireless apparatus. BRITISH THOMSON-HOUSTON CO., Ltd., Crown House, Aldwych, London. -(Assignees of Stephenson, H. M. ; 1002, Northwood Boulevard, Fort Wayne, Indiana, U.S.A.) Dec. 31, 1931, No. 36098. Convention date, Dec. 31, 1930. [Class 37.] The tuning element and volume control of a radio receiver are controlled by a single shaft having means for controlling each separately or both simultaneously ; extreme movement of the volume control adjustment actuates an on-off switch. The tuning condenser 1 is controlled by rotary movement of the shaft 8 and knob 9 by a cord drive 15 and spirallygrooved drums 12, 13. The shaft 8 is grooved as at 20, set-screws 21, 22 in the drums engaging in the groove so as to permit lateral movement of the shaft. Conversely, the toothed rack 23 is secured to the shaft 8 by set-screws 24 engaging in transverse slots so that the rack is unaffected by rotary motion of the knob but is displaced by longitudinal motion, thereby operating the volume control 4. Displacement of the rack 23 to its extreme positions switches the receiver on and off through a toggle switch 25 by engagement of studs 29, 30 with the arm 28. In the modification shown in Fig. 4, the rack 23 is formed as a worm wheel, the thread pitch being so graded that as the tuning is varied the volume control is also varied to give a constant output thus compensating for variation in overall amplification over the tuning range ; longitudinal movement of the shaft 8 provides rapid volume control and switching as before. A circuit diagram showing the arrangement of the volume control 4, condenser 1, and switch 25 is shown in Fig. 2. Specification 291,728, [Class 37, Electricity, Measuring &c.], is referred to.