Patent GB-532860-A (GB)
Title: Improvements in the tuning mechanism of radio receivers
IPC: H03J5/18
Filed: 1939-09-23
Abstract: 532,860. Electric control systems. PHILIPS LAMPS, Ltd. Sept. 23, 1939, No. 26515. Convention date, Sept. 26, 1938. [Class 40 (i)] A station is selected on a remote key-board or selector disc. Keys in the receiver are actuated from a shaft driven by a motor which is energized simultaneously with a selective device to cause only the key corresponding to the selected station to become operative. In one form, the shaft has a number of cams by which each of the keys is pressed successively, on one revolution of the shaft. In another form, the shaft carries one cam which, as it rotates, presses the keys successively. According to the first example, and as shown in Figs. 1, 3, if a button, such as 5, in the control panel is depressed, a contact 48 is closed also, whereby a relay is energized by current from terminals 56, 57, to close contacts 45, 46, to motor 42, and at the same time to withdraw pinion 50 from wheel 52 to engage wheel 51 driving a shaft 43, bearing cams 21 .. 30, and contact arm 47. When this arm 47 on the selective device reaches contact 15, connected to the key 5, the relay 44 is short-circuited, and the motor 42 is then in circuit through contact 45 and a reversing contact 60, with the mains terminals 58, 59, the de-energizing of the relay allowing gear 50 to drive the condensers 53 ... 55 through gearwheel 52, to the desired tuning point, when a projection such as that shown at 110, Fig. 6, already under tension from its cam, falls into a slot 113 on the appropriate one of a number of discs 112 on the condenser spindle. In a modification, Fig. 2 (not shown), all the contacts of a selective device, such as that served by the arm 47, are at the same potential, except that connected to the one button 1 ... 10, that is selected and pressed, so that the motor is energized wherever the arm is, to cause the arm to rotate until the circuit is broken opposite the contact selected. The direction of rotation is governed by the two-way switch 60, which is in contact either with 61 or 62, connected to the two extremities of the winding of the motor 42. The discs 112 on the condenser spindle have half their periphery 109, 111, of different radius, as in Fig. 6, and the particular half upon which the projection 110 falls, determines with which of the contacts 61, 62, the arm 60 makes contact. In the second form of key-actuation, Fig. 5, depression of a button, 86 ... 89, on the remote control key-board, causes the motor 70 to rotate, driving the arm 75 until it makes contact with the corresponding stud 76 ... 79, in which position the two windings are short-circuited across a condenser 85. Simultaneously, the gearwheel 72, bearing a cam 73, has been rotating, depressing the pins 163, 164, successively, until, when the motor stops, the overlapping plates of the tuning condenser 160 are in a pre-determined position, governed by the longest pin 163 passed by the cam. A hand tuning of this form is described. The form of selective device shown in Fig. 6, has a series of cams 103, on a shaft rotated by a motor as before, but, in this instance, the actuation of the particular projection 110 on its spring 233 which would locate the tuning-condenser disc 112 corresponding to the button depressed, depends on the closing of a circuit through a magnet 126 by the button, so that a pawl 101 is drawn into the path of a tappet 104, to transmit the movement by key 35 and spring 240, at the same time starting the motor by closing contacts 236, 237, 60 and 61 or 62.