Variable capacitors consist of interwoven metallic plates, with one fixed and the other adjustable, allowing capacitance values between 10 to 500pF. The document describes tuning capacitors, which include a stator, rotor, and a mica capacitor, and explains how adjusting the rotor alters the capacitance. A ganged capacitor combines two capacitors for functionality with a single shaft controlling both.

7. Variable Capacitors
Variable capacitors in general consists of interwoven sets of metallic
plates in which one is fixed and the other is variable. These
capacitors provide the capacitance values so as to vary between 10
to 500pF.

8. The ganged capacitor shown here is a combination
of two capacitors connected together. A single shaft
is used to rotate the variable ends of these
capacitors which are combined as one.
The main types of variable capacitors are Tuning
capacitors and Trimmer capacitors.
Tuning Capacitors
Tuning capacitors are popular type of variable
capacitors. They contain a stator, a rotor, a frame to
support the stator and a mica capacitor.

9. The rotor plates when moved into the slots of stator, they come close
to form plates of a capacitor. When the rotor plates sit completely in
the slots of the stator then the capacitance value is maximum and
when they don’t, the capacitance value is minimum.