文档介绍：毕业设计(论文)外文翻译
原文题目: DIGITAL VOLTMETER
DIGITAL VOLTMETER
BACKGROUND OF THE INVENTION
This invention generally relates to voltage measurement devices, and more particularly to digital voltmeters capable of measuring AC and DC voltages with automatic selection of the proper measurement function so as to provide a safe measuring instrument. The digital voltmeter of the invention may also provide a measuring instrument which is substantially insensitive to the
effects of distributed capacitance, for accurate and reliable voltage measurement.
Many situations, from checking and testing of electrical service installations to checking the integrity of residential wiring, require the use of voltage measuring equipment capable of measuring the magnitude of an AC line voltage, DC voltage bination thereof. It should be evident that in the verification of electrical service voltage, very high voltages may be encountered, making routine power measurement a possibly dangerous activity. For providing such measurement capabilities, there have been developed a number of AC/DC voltage reading voltmeters or mufti-function meters adapted to measure voltage in conjunction with other electrical parameters.
In this respect, various AC and DC analog voltmeters have been developed which operate with a galvanometer type meters to indicate the magnitude of the voltage being measured. Many of these analog type instruments are deficient in that they have low input impedance and therefore require a substantial amount of electrical current to deflect the meter, which will distort the voltage measurement in many cases. Digital voltmeters have also been developed which may avoid the uracy of some analog meters, but in turn have other recognized deficiencies.
Both analog and digital voltmeters are subject to uracy, are bulky, fragile and the user thereof is possibly dangerous. Many such meters include range and function selection switches which are manipulated by the user. The voltmeter m