Patent GB-558351-A (GB)
Title: Improvements in or relating to electrical relays or converters
IPC: H01C10/10
Filed: 1942-03-12
Abstract: 558,351. Converting. SCHMIDT, K. H. March 12, 1942, No. 3283. [Class 38 (ii)] [Also in Groups XXXVI and XXXIX] Apparatus for controlling the flow of current in an electric relay, a D.C./A.C. converter, or a D.C./D.C. transverter includes a pack consisting of a combination of conducting and semi-conducting materials in powder form adapted to be interposed in a circuit containing a source of supply and means for applying pressure to the pack. Suitable semi-conductors are CdS, PbS, ZnO, MgO, MoS 2 , FeO, CuI, Cu 2 O, UO 2 , NiO, Al 2 O 3 , WO 2 , CuS. Fig. 1 shows a relay including a pair of spaced diaphragms 8, 9 enclosing a layer 10 of a mixture of iron filings and copper sulphide, the diaphragms being supported and spaced by insulating members 11. The diaphragms are in a circuit containing a battery 6 and ammeter 7. The lower diaphragm 9 carries a coil 13 which is free to move axially in a gap between polepieces 14, 16 of a ring type permanent magnet 15. The coil 13 is in series with a battery 18 and a variable resistance 19; variation of which causes movement of the coil 13 and consequent change of pressure on the layer 10. Fig. 2 shows a D.C.-A.C. converter including a ring-shaped permanent magnet 20 concentric with a mild steel cylinder 21 leaving a gap in which is an axially movable coil 22 rigidly fixed at its ends to diaphragms 23, 24. Two further diaphragms 25, 26 are spaced from these diaphragms to form intervening spaces which are packed with a mixture of conducting and semi-conducting material. Axial movement of the coil increases the compression on one pair of diaphragms and decreases that on the other. The low-tension winding 33 of a transformer 32, Fig. 6, has a central tapping connected to a battery 34, the other terminal of which is connected to the diaphragms 25, 26. The movable coil 22 is connected to the diaphragms 23, 24 and to the low-tension winding 33 of the transformer, the high tension winding 35 of which is connected to output terminals. Oscillation of the movable coil causes an increase in current in one half of the winding 33 and a decrease in the other half, which induces an A.C. impulse in the transformer. This is fed back into the moving coil and keeps the system oscillating thus producing an uninterrupted and smooth flow of alternative current. By inserting another pair of powder packs synchronous rectification can be effected. Fig. 4 shows a D.C.-DC. transverter, in which a second powder pack is interposed at each end between the diaphragms 25. 26 and their adiacent end plates 29. The coil 22 is connected to the diaphragms 23, 24 by corrugations 36. The connections are shown in Fig. 7. The diaphragms 25. 26 are connected together and earthed, one side of the battery 34 also being earthed. The end plates 29 are insulated and connected to opposite ends of the high tension secondary winding 35, which has a central tapping connected through an iron-cored choke 37 with the positive terminal of the D.C. output. The negative output terminal is earthed, smoothing condensers 38 being connected across the output terminals. from which a direct current is obtained of either a higher or lower voltage than that of the battery. An electromagnet mav be emnloyed instead of a permanent magnet for applying pressure to the nack, the contact materials being placed between the core and armature of an electromagnet the windines of which are energized by the controlling current. Alternatively electrostatic means may be employed.