| 摘要 |
865,941. Moving-iron voltmeters. HEL. LIGE & CO. G.m.b.H., FRITZ. May 26, 1959 [May 27, 1958], No. 17818/59. Class 37. In a valve voltmeter incorporating a moving- iron meter excited by a pair of windings 7a, 7b, Fig. 1, the windings are commoned at 7c and connected in the respective anode leads of a pair of screen grid valves 2, 3 arranged in pushpull, the screen grids 2b, 3b being supplied from point 11a between damping impedances 9, 10 connected across the windings. The meter operating current, i.e. anode current + screen current may be supplemented by a further current such as that fed to a load 24. In a modification, described with reference to Fig. 2 (not shown) the screen feeds are tapped from separate points on the damping impedance to provide positive or negative feed-back, and an interconnected cathode resistor arrangement provides current feed-back. The meter may comprise permanent magnet armature, or a soft iron armature 8, Fig. 4, moving in a magnetic frame 28 carrying windings 7a, 7b, the indicator or recorder being carried by the armature which is returned to a defined inoperative position by a helical spring when the meter is de-energized.
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