Material level detector circuit

摘要: Disclosed are apparatus and methods for detecting the presence, or absence, of material at a predetermined location. An oscillator generates constant-frequency, constant-amplitude signal which is fed through load resistor to an antenna probe positioned sensing The amplitude varies as impedance affected by in its environment, lack thereof. converted into d-c voltage level, transmitted switching circuit provides output depending on comparison between level reference level. sensitivity adjustable accommodate degree particular material, whose presence absence be detected, affects probe. from may used operate one more devices indicative environment and/or affecting adding removing therefrom