Force-balance Coil This photo shows the force-balance coil in the center. The windings are red in color and form a cylinder that extends into the magnet (the cylindrical thing partially hidden behind the suspension web). The coil and magnet arrangement is much like that of a loudspeaker. One pole of the magnet is a cylinder in the center and the other pole is a hollow cylinder surrounding the coil. The coil is attached to the boom with screws and the wires from the coil run along the boom to near the pivot.

To the right of the coil, the square box is the lead mass, and the stops are the square bars above and below it. The boom web is also visible soldered to the brass tubing that forms the boom.