GB1071968A - Circuit arrangement with at least one non-linear dielectric element operating in the state of thermal autostabilization - Google Patents

Abstract

1,071,968. D. C. voltage measurement. CESKOSLOVENSK‡ AKADEMIE VED. Nov. 4, 1964 [Nov. 6, 1963 (2)], No.44939/64. Heading G1U. [Also in Division H3] A D. C. amplifier, e.g. for use in a voltage measuring circuit, utilizes a tandel (a non-linear dielectric element operated in the state of autostabilization close to the Curie temperature) the bias on which is provided by the D. C. input signal to control the amplitude of even harmonics in an output circuit, and a selected harmonic being synchronously detected to provide a D. C. output. In the electrometer of Fig. 4 two tandels C N , C<SP>1</SP> N are connected in a bridge circuit with two linear impedances, e.g. capacitors Z, Z<SP>1</SP> and the D. C. input voltage is applied between V 1 and V 2 . A variable bias source B is provided for initially balancing the bridge. The bridge output diagonal includes a series resonant circuit L 1 , C 1 coupled to a parallel resonant circuit L 2 , C 2 tuned to twice the frequency of the supply from generator G, which serves both to energize the bridge and to heat the tandels. The second harmonic output is amplified and supplied to a synchronous detector S.R. which also receives a reference input derived from a frequency doubler N connected to source G. The D.C. output from S.R. is measured at M. It is stated that one of the elements C N , C<SP>1</SP> N may be a non-linear capacitor other than a tandel.