An all-electronic four-digit digital voltmeter

The paper describes a four-digit electronic digital voltmeter and deals with the mode of operation of this instrument and a number of problems that have been solved in engineering it. A feature of the instrument is the automatic range change circuit which operates the input attenuator and minimizes the errors arising from the reverse grid current flowing in this attenuator. The fundamental accuracy of the instrument depends on the method of voltage comparison and particular emphasis is placed upon drift correcting these comparators using the principle of time-sharing. The generation of linear ramps is desribed and results of laboratory measurements verifying theoretical predictions are given. The high speed decimal counter using the trochotron tube is described and shown to be ideally suitable for operating with neon-type number tubes. The paper closes with the discussion of all the errors.