GB510713A - Control devices for radio receivers - Google Patents

Abstract

510,713. Time switches; electromagnetic switches. KOLSTER-BRANDES, Ltd., and SMYTH, C. N. Feb. 4, 1938, No. 3577. [Class 38 (v)] [Also in Group XL] In an arrangement for the automatic control of a wireless receiver comprising a plurality of timeoperated switches each adapted to control the energising circuit of a relay which effects a predetermined change in the receiver controls (e.g., tuning, volume &c.), each relay is provided with "on" and " off windings the circuit connections being such that when an "on" winding of one relay is energised, the " off windings of all the other relays are energised so that only one tuning control can be operated at any one time. In Fig. 2 each toggle relay has an " on " winding Ln and an "off " winding Lnn energisation of which causes the armature 5 to operate " on " and " off " switches respectively mounted on the insulation members 3 and 4. In Fig. 1 the " on " and " off " windings L1 .. Ln and L11 .. Lnn of each of the relays R1 .. Rn are connected in series with their respective time switches S1 .. Sn across the current supply E, and the common terminals R1 .. Rn of all the pairs of windings are connected together so that on closing the switch Sn the " on " and "off" windings of relay Rn and the "off" windings of all the other relays are energised. The " on " windings are more powerful than the " off " so that when both are energised the relay is operative in the " on " position. In an alternative circuit in Fig. 4 each time switch comprises two contacts and the " on " winding only is energised through contacts XI .. Xn for the " on " position and the other winding is energised through contacts S1 .. Sn for the "off" position. The " on windings L1. Ln are connected to the current supply E through normally open contacts X1 .. Xn and through the normally open common contact So. The "off" windings L11 .. Lnn are connected to the supply E through the normally closed contacts SI .. Sn and the contact So of the relay Ro which is in the anode circuit of the valve V. The " off " windings are also in parallel with the resistance R2 included in the grid circuit of the valve V which is biassed to cut-off. Current is supplied to the resistance R2 from the high tension supply through the resistance R1. Operation of a time switch Sn-Xn momentarily opens Sn and closes Xn, thus removing a parallel circuit from the resistance R2 resulting in increased voltage across the resistance which causes the valve to pass current and so operate the relay Ro. Thus the " on " windings of the relay Rn and the "off windings of all the other relays are energised. The time switch contacts may be circumferentially adjustable round a dial, Fig. 3 (not shown), and operated by a cam rotating with the hour hand of a clock, or they may be horizontally adjustable, Fig. 5, and operated by a transverse contact strip 17 on an endless belt 13 in which case the circuit may be completed through the contact 201, 202 ... contact strip 17, belt 13 and contact brush 19. Alternatively, the contact strip may act purely as a cam.