Double gang air variable capacitor with reduction gear. Dielectric, often used in radio tuning circuits. Variable capacity of an old tube radio. Close up

Double gang air variable capacitor with reduction gear. Hand turns the rotor of a tube radio capacitor for station tuning.

Close up of double gang air variable capacitor with reduction gear. Male hand turning the rotor of a tube radio capacitor for station tuning. Dielectric, often used in radio tuning circuits

How to make your own variable tuning capacitor - EDN

D.I.Y. Variable Capacitor

Motor starting capacitor | Applications | Capacitor Guide

Capacitor Types, Parts & Examples