| 摘要 |
<p>A control circuit for a coulometric titrator having a recording voltmeter connected therein. The circuit utilizes two transistors of opposite conductivity types between which a low pass filter is connected. An emitter bias resistor is employed with one transistor. A zener diode and a resistor provides quiescent bias for the other transistor. The one transistor is provided with a base bias that is adjusted through the use of a potentiometer to cause both transistors to operate slightly above cut-off when the monitored fluid concentration is zero. The zener, the filter and the one transistor emitter resistor all improve the signal-to-noise ratio at the voltmeter without reducing the voltmeter dynamic response or accuracy of indication. The extraordinary range of the instrument is, for this reason, down to two parts per billion.</p> |
