Electronic pressure sensor based on HF oscillator - varies capacitance of parallel resonant circuit according to pressure

摘要

The sensor housing (1) is a tube with an extended base (2) at one end and a connection tube (3) at the other. The connection tube is sealed by a conductive membrane (5) to which the gas or liq. pressure is applied. In the housing inner space (4) is a coaxial bar (6), the free end (7) of which is one plate of the capacitor; the membrane (5) being the other. The inductance is formed by the housing and half the bar. The electrodes of the resonant circuit are linked into a single transistor oscillator, the output frequency of which is divided before comparison with a reference frequency. The output of the comparator is filtered and further divided to produce a pressure-relative output.