Send current protection circuit with thermistors

Published:2011/8/26 3:01:00 Author:Jessie | Keyword: Send current protection, thermistors | From:SeekIC

The circuit can be usedto prevent the liquid in containeroverflow. T1 is constant current source, R2 is thermistor and sensor which is used to heat. The media types and temperature regulation ofthe place of sensor could make current flowthrough sensor and produce heat whichis equal to the heat from surrounding media emissions. Now assuming R2 is in air, so emissionsheat is small, R2 temperature will increase to the highest, R2 resistance is low. As a result, A's potentialis high, T2 and T5 are connected, so is the relay. If R2 dip in fluid-filled containers, then R2's temperature drop, its resistance increases, A's potentialis low, T2 and T5 are disconnected,neither is the relay. Thus, it can be used to detect liquid face whether has overflow.



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