| 摘要 |
An electronic pump switching system comprises a water sensor coupled to a comparator which generates an output signal when water is sensed. The comparator output is coupled to a timer, which is initiated for a predetermined period by the comparator output signal. The timer is coupled to a switch which activates a coupled device, such as a pump, for the predetermined period. The continued presence of water at the sensor at the end of a predetermined period causes the timer to time a new predetermined period, whereby the coupled device remains activated. The sensor may be formed from a pair of electrodes arrayed as a voltage divider. The voltage divider action may additionally serve as a discriminator, allowing timer operation to be tied to the detection of water, as opposed to petroleum products, such as fuel.
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