GB518941A - Improvements in or relating to electric selective control systems - Google Patents

Abstract

518,941. Electric control systems. PHILCO RADIO & TELEVISION CORPORATION. Sept. 9, 1938, No. 26365. Convention date, Sept. 9, 1937. [Class 40 (i)] In a system for selectively positioning a member, e.g., the tuning member of a radio receiver, the member 1 is driven by a motor 8 under the control of coarse and fine selectors 2, 3 which are associated. with manual push buttons 42 through an automatically operated change-overswitch 34. The coarse selector is mounted on the shaft 4 of the member 1 and the fine selector is geared to the member by gearing 6, 7 and is driven by the motor 8. The coarse selector comprises arcuate contacts 10, 11 and an intermediate diametral contact 12 co-operating with adjustable preset contacts 20 connected to the buttons. The fine selector 3 consists of arcuate contacts 23, 24 separated by an insulating strip 25 and co-operating with preset contacts 32 also connected to the buttons. When a key is operated a magnet 41 of the switch 34 is energized and the switch operated to associate the buttons with the coarse selector 2. A circuit for the motor 8 is also completed over the selected contact 20 and the motor is driven in one or other direction until the circuit is opened. In this position the contact 12 engages the selected contact 20 and a circuit for the electromagnet 40 is completed to operate the switch 34 and connect the keys to the fine selector 3. The motor is then further operated to adjust the member 1 until the circuit of the selected contact 32 is opened by the insulating strip 25. The push buttons are associated with locking pawls which are arranged to retain the operated button in its operated position and to release the previously operated buttons. A lamp 5,1 may be switched into circuit with the motor to prevent operation of the motor during presetting.