GB903444A - - Google Patents

Abstract

903,444. Electric analogue calculating; power measurements. LANDIS & GYR A.G. May 11, 1960 [May 13, 1959], No. 16643/60. Class 37. In a circuit wherein a semi-conductor of, e.g. germanium, silicon, or indium arsenide is subjected to a magnetic field to develop a resistance proportional thereto which is traversed by a current developing a voltage drop proportional to the product of the field and the current magnitudes, it is shown that the resistance R Bt for field B at temperature t is given by where R oo is resistance for B=0, t = 0; a is a constant; and that if the current it is given by where i o is the current for t=0, the developed voltage drop representing the product remains constant with temperature change (Fig. 1, not shown), so that connection in series with the semi-conductor of a resistance of comparatively high valve and similar temperature coefficient compensates for the temperature variation of the semi-conductor. In Fig. 2 a semi-conductive disc R B is energized with a voltage e from transformer 6 energized across mains 8 in series with a resistance W of value greatly exceeding that of R B under operating conditions; and the disc is subjected to a magnetic field B from coil 9 energized in series with mains 8. Resistance W has a temperature characteristic similar to that of R B , given by where W t , W o are resistance values at temperatures t and 0 so that the current i is given approximately by and the voltage drop across R b measured by instrument 10 is proportional to the alternating current power in mains 8. Resistance W may be of the same material as resistance R b or may be composed of a suitable network of positive and negative temperature coefficient resistors.