An electrostatic voltmeter possessing several unique features is described. The size is a minimum for such instruments, since the potential difference is applied to two electrodes, the geometrical arrangement of which is analogous to concentric spheres. The inner electrode is supported on the end of an insulating bushing introduced through the outer electrode, which is a metal can. The inner el...

Modern instruments use sensors, analogue and digital electronics, processing to measure almost any kind of physical quantities. Arduino is a very useful widely used platform build such systems in school environment. Since it has voltage inputs, can be as voltmeter or even chart recorder. However, the ways ensuring required level accuracy just right estimation are often unknown misunderstood. In...

We describe the development of a multi-frequency electrical impedance tomography (EIT) system (KHU Mark1) with a single balanced current source and multiple voltmeters. It was primarily designed for imaging brain function with a flexible strategy for addressing electrodes and a frequency range from 10 Hz-500 kHz. The maximal number of voltmeters is 64, and all of them can simultaneously acquire...

This article proposes a method for reducing the loading effects when DC voltage or current is measured in linear circuit with digital multimeter (DMM). In proposed method, voltmeter placed series to estimate current, and ammeter parallel voltage, which opposite of conventional approach. Its application particularly interest equivalent resistance between nodes (current) under measurement high (l...

Timebase distortion causes nonlinear distortion of waveforms measured by sampling instruments. When such instruments are used to measure the rms amplitude of the sampled waveforms, such distortions result in errors in the measured root-mean squared (rms) values. This paper looks at the nature of the errors that result from nonrandom quantization errors in an instrument’s timebase circuit. Simul...

This research embodies the design, construction and simulation of a feeder pillar (415VAC) with over-current, overload and earth-fault protection with the aid of a phase sequence relay, contactor, earth-leakage circuit breaker and three-phase overload relay. The analog voltmeters in the various bus-bars (red, yellow and blue phases) in a conventional feeder pillar is replaced with a digital pan...