| 摘要 |
A monitoring circuit for monitoring a plurality of signals developed by remote sensors which preferably are capacitance probe sensors. The circuit is intended for use with a motor vehicle maintenance system employing capacitance probes to detect low and safe levels of oils and coolants in a vehicle engine. The monitoring circuit includes a constant voltage source with a voltage divider in circuit therewith to develop a plurality of reference voltage signals of predetermined values which are applied to respective inputs of a plurality of voltage comparators that receive, at their other terminals, condition-responsive voltage signals generated by a condition sensing circuit. The condition sensing circuit comprises a liquid level capacitance probe which generates intermediate, high and low voltage signals indicative of safe and low, respectively, levels of sense liquid. Open or shorted leads in the sensing circuit generate zero and maximum voltages, respectively, which are also applied to comparator circuits, whose outputs activate visible indicators to register safe and unsafe liquid level, and shorted or open sensing circuits.
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