GB443640A - Improvements relating to radio receivers and to apparatus for use therein or for analogous purposes - Google Patents

Abstract

443,640. Wireless receiving-apparatus. COLE, Ltd., E. K., Priory Crescent, Southendon-Sea, and BRADFIELD, G., 161, Hainault Avenue, Westcliff-on-Sea. Aug. 31, 1934, No. 25058. [Class 40 (v)] In a radio-receiver of the kind having manual tuning con trol and automatic means for ensuring final accuracy of tun ing, a step by step movement is auto matically imparte( to the tuning element which movement is arrested when the receiver is in tune with the signal. In the arrangement shown in Fig. 1, a spur wheel A carrying a spring-loaded paw B is rigidly mounted on the shaft M of the tuning element. A ratchet wheel N is rotatably mounted on shaft M and has a flange over which passes a cord L kept in tension by spring H, the cord being attached to the armature O of an electromagnet P. An escapement D, pivoted at E, carries a weight F, and a second electromagnet K has an armature G with two stops J preventing movement of the escapement D when the magnet is de-energized. When the receiver is within a predetermined degree off-tune, electromagnets P and K are energized by a manually operated switch ; the ratchet H is rotated anticlockwise by cord L. The energizing circuit of P is then broken and the ratchet N, spur wheel A and tuning element of the receiver are rotated in a clockwise direction by the action of spring H. Rotation of A is permitted by oscillation of escapement D and weight F until the holding current of electromagnet K ceases, which is when the receiver is in tune. The armature G then falls, thus preventing movement of weight F and also of spur wheel A. The circuit arrangement shown in Fig. 2, shows the output stage 4 of a receiver coupled to a reproducer 5 through transformer 12 in one position of a switch contact 11<1> and through an impulse rectifier 6 to one energizing coil 7 of magnet K, Fig. 1, in the other position. The energizing coil of magnet P, Fig. 1, is fed from the high tension supply through resistance R and switch contacts 1<1>, 21, and the second energizing coil 11 of magnet K is fed from the same source through resistances 8, 10 and contacts 31, 4<1> with a shunt condenser 9 as shown. All the contacts are arranged for operation by a single switch button 13, Fig. 3, so that in one position contacts 11, 2<1> ; 3<1>, 4<1>; 101, 11<1>; 15<1>, 16<1> are closed, energizing the two magnets as described previously. The automatic tuning then follows and the switch contacts are returned to their initial position. Contacts 31, 4<1> may be replaced by a spring device operated by knob 13 to throw arm G, Fig. 1, out of engagement with weight arm EF, Fig. 4 (not shown). Specification 443,363 is referred to.