GB220283A - Improvements relating to devices for locating conducting bodies or bodies capable ofbeing magnetised - Google Patents

Abstract

220,283. Geffcken, R. H. H., Richter, R. H., Wetzel, M. H., and Wetzel, M. K. Aug. 6, 1923, [Convention date]. Locating conductors.-In method of locating conductors or magnetizable bodies by the change of frequency produced in an oscillating circuit, two or more oscillating systems are coupled together and adjusted so that by the variation of the natural frequency of one of the oscillating systems, considerable variations occur in the coupling frequency or the frequency of one of the oscillations present. Fig. 3 shows an arrangement in which an oscillating system containing an inductance 8 and a condenser 9 is excited by a thermionic valve 10 and is coupled through a variable coupling 13 to a second oscillating circuit containing an inductance 6 and condenser 7. The curve 14 Fig. 2, shows the relation between the wave length and the inductance in the circuit 8, 9, the curve 15 showing the same relation for the circuit 6, 7. The opposed portions of the curves 14, 15 may be utilized by arranging the inductances 6, 8 in the form of a cross and allowing them to rotate about the axis of intersection. On the approach of a conductor an increase in frequency alternates with a decrease. Alternatively two arrangements as shown in Fig. 3, together forming an interference tone, are employed. in one of which the inductance 8, and m the other the inductance 6, are exposed to the action of a conductor. The frequency of one generator is increased and of the other decreased on approach of a conductor, causing a charge in the interference tone. The exposed coils may form a cross. In a modification two excited systems may be coupled together. The coupling may be inductive, conductive, capacitive, resistance, or a combination of these. Specification 147,440 is referred to.