Which component is not part of a coil machine?

• A. Tubes
• B. Coils
• C. Frame
• D. Armature

Answer: (A)

A coil machine is built around its frame, coils, and the moving armature bar driven by springs. The frame is the structural backbone that holds the coils, armature, and other parts in place. The coils create the magnetic field that pulls and releases the armature, producing the up-and-down motion that drives the needle. The armature is the moving piece that translates that magnetic force into needle movement.

The tube, however, sits outside this electromagnetic and mechanical core. It’s used to guide the needle and hold the cartridge, serving more as part of the needle assembly or handpiece rather than the coil machine’s internal mechanism. Since it doesn’t participate in generating magnetism or driving the armature, it isn’t considered part of the coil machine’s essential components. That’s why the tube is the correct answer.