Combined vacuum meter for laboratory use

Abstract

A combined vacuum meter for the measurement of pressures in the range 1–10−5 mm Hg is described. Pressure measurements between 1–10−3 mm Hg are carried out by thermoelectric method by means of a bridge circuit with provisions for the protection of the meter. The measurements in the pressure range 10−3–10−5 mm Hg are based on the principle of cold cathode ionisation. The voltage supply is stabilized against line voltage variations by a series resonance circuit containing a ferromagnetic core inductor. A qualitative description of the stabilization is also given.