Non-contact sensor alarm circuit

Published:2011/6/24 10:54:00 Author:Fiona | Keyword: Non-contact, sensor alarm | From:SeekIC

G is representative of sensors in the picture,there is a distributed capacitance Co existing between G and ground, capacitance three-point oscillator composed of Co and L, C1, V1,in the return circuit composed of Co, C1, L,in the view of alternating current path,C0 and C1 are connected in series. When no one is close to G,Co is small,when it connected in series with C1, both ends of the partial pressure of Co is greater than both ends of the partial pressure of C1,the both ends high frequency voltage of Co is fed to V1 base through C3,it's enough to keep three-point oscillator to produce oscillation.



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