Electromechanical torsional oscillator with resonant frequency and amplitude control

Claim 1

An electromagnetic actuator comprising: first and second "C" shaped core members of soft magnetic material each having a pair of opposing pole faces defining an air gap, first and second permanent magnet means connecting said "C" shaped core members to create similar magnetic poles at the opposing pole faces of said "C" shaped core members, an armature of soft magnetic material, torsion bar means for supporting said armature for movement about the center of mass of said armature with the ends of said armature positioned largely within the air gaps of said "C" shaped core members, a drive winding on said first "C" shaped core member, adapted to be energized with an alternating current drive signal to create a differential flux density between said armature and opposing pole faces of said first "C" shaped core member causing said armature to move initially in the direction of the pole face having the air gap with the higher flux density and thereafter, to oscillate at the frequency of said alternating current drive signal, and variable impedance means connected in series with said drive winding for selectively adjusting the Q of said actuator.