| 摘要 |
<p>A circuit (10) for detecting the presence of an electrolyte, e.g. detergent, bleach or rinsing agent, in the feedtube (21) of a dishwasher comprises a non contacting capacitance sensor (20), an oscillator (12), pulse shaper (14) to generate rectangular pulses, a potentiometer (16) for setting the sensitivity, a comporator (22) for detecting changes in the duty cycle of the oscillator arising from changes in capacitance, and a rectifier circuit (24) for producing a DC output.</p> |
