vacuum-tube electrometer

electronics

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July 14, 2026

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A vacuum-tube electrometer is a highly sensitive instrument used to measure very small voltages and currents. It functions as a direct-current amplifier, capable of detecting currents as low as 10^-15 amperes. This sensitivity makes it useful for applications where drawing even minimal current could alter the measurement, such as in vacuum-tube circuits. While effective, these devices can experience drift, and newer versions may use field-effect transistors or operate at extremely low temperatures for stability. Electrometers, in general, are used in fields like studying cosmic rays and in chemical analysis.1

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electrometer
…more sensitive device is the vacuum-tube electrometer, a direct-current amplifier capable of measuring currents as minute as 10^-15 amperes (about 10,000 electrons per second). This instrument, however, is subject to drift. A newer version of this type of electrometer replaces the electron tube with a matched pair of junction field-effect…
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…more sensitive device is the vacuum-tube electrometer, a direct-current amplifier capable of measuring currents as minute as 10^-15 amperes (about 10,000 electrons per second). This instrument, however, is subject to drift. A newer version of this type of electrometer replaces the electron tube with a matched pair of junction field-effect…
Read More