Electrometer-DC-Amplifier-RVFM-614-006-Designed-for-ease-of-use-&-superior-performance-while-used-for-measurement-of-small-current-small-charge-or-time-constant-for-RC-experiments-Rotary-switch-of-extremely-high-insulation-resistance-500G-Omega-is-employed-to-select-resistors-or-capacitors-to-discharge-the-capacitor-or-leave-them-open-BR-BR-Typical-half-times-for-this-unit-for-the-built-in-1n F-100GO-or-100n F-1GO-RC-pairs-are-from-67-to-71-seconds-against-theoretical-values-of-