Air flow detection circuit diagram

Published:2014/4/23 20:07:00 Author:lynne | Keyword: Air flow detection circuit diagram | From:SeekIC

Figure LM335 work is the use of self-heating effects to detect the flow of gas. ST1 placed in still air, lower operating current of approximately 1mA. ST2 placed in the external environment, the operating current is large, about 10mA. ST3 operating current is large, and in the air does not flow from the heat generated during its rise above STl temperature rise, so LM301 comparator inverting input voltage is higher than the non-inverting input voltage. Output is low. When the external ambient air flow, the heat generated ST2 continuously taken away to the surrounding air, so the temperature rise caused by thermal effects from reduced. And then STl in still air, heat transfer is very slow, so the self-heating effects caused by the rise in temperature is greater than ST2, the LM301 comparator output goes high, driven LED lights alarm. By Rp alarm point can be set air flow rate.



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