The History of Electric Measuring Instruments and Active Components Society of Historical Metrology , Japan
Precision electric meters are indispensable to the development of technology in this age. The first electric measuring instruments, however, were physically impossible to transport, and were functionally inadequate for use in a laboratory. The measuring instruments of today have evolved into sturdy, easy-to-use instruments with higher performance, adopting new active components which have appeared one after another. Expanding in functionality, measuring instruments that have adopted such new technology have enabled even more precise measurement. The users have also expanded from research organizations and educational facilities, to the manufacturers of electrical equipment and electronic parts. The measuring instrument manufacturers were able to supply more convenient measuring instruments to the user, and conversely, the user, the manufacturers of electrical equipment and electronic parts, needed more easy-to-use and highly precise measuring instruments in order to respond to a rapidly increasing demand. Consequently, cheap and high quality electronic parts were supplied to the market, and the measuring instrument manufacturers were also able to develop new measuring instruments using those parts. In fact, it can be said that they have been mutually complementary. It should not be forgotten that the demand for electronic components for consumer use has also driven the whole in the meantime.
Stabilized feed-back amplifiers
This paper describes and explains the theory of the feed-back principle and demonstrates how stability of amplification, reduction of modulation products, and certain other advantages follow when stabilized feed-back is applied to an amplifier. The underlying principle of design by means of which “singing” is avoided also is set forth. The paper concludes with some examples of results obtained on amplifiers which have been built employing this new principle.
Recalculation of Mass Defects
THE well-known mass defect curve of the old nuclear scheme calculated with regard to α-particles and protons presented a difficulty with its minimum of binding energy for tin and an increasing portion between tin and lead. On the other hand, the mass defect values against protons give a rather smoothly decreasing curve.1 As has already been pointed out,2 the number of α-particles must be considerably reduced from the point of view of the new scheme, which does not admit any electrons in nuclei, but only neutrons and protons (presumably joined as α-particles). The curve of mass defect against protons and neutrons (perhaps with a single ‘central’ α-particle) is very similar to the old curve against protons, but decreases less rapidly. Clearly the new mass defect values relatively to α-particles, neutrons and protons must lie somewhere between the old values computed relative to protons and α-particles respectively (because the number of α-particles is decreased). We may emphasise that this new mass defect curve shows no increasing portion between tin and lead. For illustration we give two typical values: Old: 50Sn124 = 31α + 12&#38;epsiv;; mass defect = 0.158 (in mass units); 82Pb208 = 52α + 22&#38;epsiv;; mass defect = 0.035. New: 50Sn124= 25α + 24ω (ω = neutron); mass defect = 0.304; 82Pb208 = 41α + 44ω; mass defect = 0.366.