| 摘要 |
An electronic circuit that controls the operation of a motor whose output shaft drives an impeller for pumping a liquid includes a common grounded electrode positioned for immersion in the liquid, and a stopping electrode positioned above the common electrode. A first, latching transistor is connected to the stopping electrode which is connected to ground through the liquid when the level thereof reaches or exceeds the level of the stopping electrode. A second, power transistor operates the motor when the second transistor conducts in response to its grounding, the second transistor being connected to the starting electrode so as to be grounded when the level of liquid reaches the starting electrode. Finally, an interconnection is provided connecting the second transistor to the first transistor such that initial conduction of the second transistor effects conduction of the first transistor which maintains the second transistor in its conducting state after the liquid level drops below the level of the starting electrode.
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