Patent GB-892739-A (GB)
Title: Improvements in and relating to tuner devices for radio receivers
IPC: H03J7/30
Filed: 1960-09-16
Abstract: 892,739. Automatic tuning arrangements. GENERAL MOTORS CORPORATION. Sept. 16, 1960 [Sept. 30, 1959], No. 31938/60. Class 40(5). In a signal seeking tuner, for a radio receiver, of the type in which the tuning elements are driven by a spring through a clutch, a single solenoid reloads the spring and resets the carriage when the carriage reaches its tuning limit and also reloads the spring when it reaches a discharged state. The Specification describes an embodiment in which tuning may be effected manually or by push buttons as well as under signal seaking control. The tuning of the dust cored coils 4, 6, 8 is effected by a bar 12 attached to the cores and controlled by a treadle bar assembly 18, 20, 22, the right hand side member 22 being directly connected to the main shaft 24, Fig. 7. The position of the tuning carriage is indicated by pointer 14, Fig. 1. Manual tuning. Continuous manual tuning is provided by rotation of knob 42 on shaft 54. The shaft 54 carries a worm 52 which engages the worm wheel 46. The wheel 46 is mounted on sleeve 70, Fig. 7, and a clutch 47, 48 is normally engaged so that rotation of knob 42 will cause shaft 24 to rotate and thus alter the tuning. Push button tuning. When any of the push buttons is depressed its initial movement strikes a tong on the clutch actuator bar 56 causing it to rotate about its longitudinal axis and disengage the clutch. This rotation brings an offset angled actuator arm 60, Fig. 7, integral with bar 56, against a roller 62 on the end of lever 64 which is pivoted at its inner end 66. The lever 64 has a central opening 68 through which a sleeve 70 surrounding shaft 24 passes. A collar 72 is secured to the sleeve 70, thus when lever 64 moves to the left, the sleeve 70 is moved along shaft 24 and in so doing it disengages a clutch member 47 on a worm wheel 46 from a fixed clutch member 48. The remaining motion of the push button causes a cam assembly to move inwards and engage rods 18, 20. This causes the treadle bar assembly to rotate to a predetermined angular position and so set the tuner to the desired station. Stop-on-signal tuning. Assuming that the tuner control bar 12, Fig.. 7, is in the rear position, i.e. the low frequency position and spring 104 is fully loaded, operation of the signal seeking switch 21 causes relay 44, Fig. 1, to lift a detent from the toothed flywheel. The spring 104 acting on the slide bar 98 and transverse rod 186 slides the worm rack 52, 174, forward along the shaft 54. This motion drives the tuner towards the high frequency position, the motion being damped by the reduction gearing 178 driving the flywheel. When a signal is tuned in, relay 44 is de-energized and drops the detent so that it engages the flywheel and stops the tuner. When the drive spring has expended its power the projection 106 on slide bar 98 strikes tong 138 and causes solenoid 76 to be energized. The solenoid pulls in armature 78 and the arm 80, the arm 80 pulls member 86 clockwise about its pivots. This causes slide bar 98 to move to the right until toe 92 engages tong 138 and causes the solenoid to be de-energized: Similarly, when the tuner reaches its high frequency limit position the toe 190 of end plate 22 causes the solenoid to be energized, the spring 104 and the tuner being returned to their initial state.