Variable scale differential transformer

Claim 1

A differential transformer comprising: a yoke of magnetic material, said yoke including an elongated base member, a first end flange extending generally transverse to said base member, a second end flange extending transverse to said base member and a third flange extending transverse to said base member interposed between said first and second end flanges, said first and third flange defining a first cavity therebetween and said second and third flanges defining a second cavity therebetween; first and second bobbins of nonmagnetic, nonconductive material seated in axial alignment in said first and second cavities respectively; first and second secondary windings of electrically conductive wire wound about said first and second bobbins respectively; first and second primary windings of electrically conductive wire wound about said first and second bobbins respectively coaxial with the respective secondary windings and electrically insulated therefrom; said primary windings being connected to one another in series opposition and said secondary windings being connected to one another in series aiding relationship; a bore extending through said third flange and said bobbins coaxial with said bobbins; an elongated core of magnetic material positioned for longitudinal movement within said bore, said core having a length greater than the width of said third flange whereby end portions of said core can simultaneously extend into said first and second cavities; and means for adjusting the position of said core.