GB1364335A - Circuits for measuring positive and negative voltages - Google Patents

Abstract

1364335 Measuring voltage INTERNATIONAL BUSINESS MACHINES CORP 19 May 1972 [11 June 1971] 23563/72 Heading G1U A voltage measuring circuit incorporating a single reference cell of either positive or negative polarity, is characterized in that any deviation of any one of a plurality of both positive and negative potentials (for example supply potentials for an electronic circuit) from its nominal value can be indicated. In a first embodiment, Fig.1, using positive reference potential, any one of four positive potentials labelled + or of three negative potentials labelled - can be compared with its nominal value which is preset by resistors R4 and R6. With a switch S in the position shown in full lines, a negative potential is connected to the measuring circuit, and by choosing the various resistors appropriately it can be arranged that when the potential being measured has its nominal value a meter 2, which may be calibrated as in Fig.3, carries sufficient current so that its needle occupies a central position labelled zero. Deviations of the potential under test are then indicated as departures from the nominal current. In a second embodiment Fig.2 (not shown) a negative polarity reference potential is used, and in a further modification Fig.4 (not shown) two switches S are employed allowing more potentials to be monitored, and a Zener diode stabilized reference potential is used.