An apparatus includes an electromagnetically conductive assembly including a first member having a first end and a second end and a second member disposed between the first end and the second end of the first member. The second member and the first end of the first member define a first gap. The second member and the second end of the first member define a second gap. A movable member moves with respect to the conductive member. A first magnet is coupled to the movable member and is disposed a distance from the first gap. A second magnet is coupled to the movable member and is disposed a distance from the second gap.