Patent ID: 8857277

Claim:
A pressure gauge for measuring a pressure of a source, comprising: a case having a bore connecting the source; a coil, which is made of a conductor, provided in the case; a magnetic device movably received in the case; and a pressure detecting circuit electrically connected to the coil; wherein the magnetic device is moved by the pressure of the source that the coil generates an induced electromotive force, and the pressure detecting circuit receives the induced electromotive force to generate a voltage signal directly proportional to the induced electromotive force; a flexible film provided on an inner side of the case to cover the bore that the pressure of the source expands the flexible film, and the flexible film moves the magnetic device; a spring with opposite ends urging the case and the magnetic device, wherein the spring is compressed when the flexible film moves the magnetic device; wherein the case includes a base and a lid engaging the base, and the base has the bore, and the lid has a chamber therein to receive the magnetic device and the spring therein; wherein the lid has a main member with the chamber therein and a threaded hole communicated with the chamber, and a knob engaging the threaded hole to contact the spring that the magnetic device is adjustable by turning the knob; and wherein a spring force of the spring for urging the magnetic device is adjustable by turning the knob.