| 摘要 |
Two electrodes immersed in an electrolyte solution shunt the gate of a "Triac" solid state switching device connected in parallel with a current-limiting resistor which is connected via an alarm device across a power source. When the electrodes are immersed below the surface of the electrolyte, they serve as a closed switch drawing minimum current through the current limiting resistor, thus biasing the "Triac" in its non-conductive mode and trickling through the alarm device at amperage levels so low that the alarm device does not respond. When the electrolyte level falls, leaving the electrodes above the electrolyte solution, they become an open circuit. This reduces the trickle current to zero and applies full power source voltage to the gate of the "Triac," triggering the "Triac" from a current blocking mode to a conductive mode. This permits an alarm current to pass through the "Triac," thereby drawing this higher amperage current through the alarm device, producing an alarm signal indicating the level of the electrolyte.
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