AN ELEMENTARY GENERATOR consists of a single coil rotated in a magnetic field. It
produces an ac voltage.
A BASIC DC GENERATOR results when you replace the slip rings of an elementary generator
with a two-piece commutator, changing the output voltage to pulsating dc.
A MULTIPLE COIL ARMATURE (adding coils to the armature) decreases the ripple voltage in
the output of a dc generator, and increases the output voltage.