A gimmick capacitor is a

capacitor A capacitor is a device that stores electrical energy in an electric field by virtue of accumulating electric charges on two close surfaces insulated from each other. It is a passive electronic component with two terminals. The effect of ...

made by twisting two pieces of insulated wire together. The capacitance may be varied by loosening or tightening the winding. The capacitance can also be reduced by shortening the twisted pair by cutting. The available capacitance is on the order of 1pF/inch (0.4 pF/cm). "... twisted-pair wire makes an excellent variable capacitor, sometimes called a ''gimmick''"

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Capacitors {{Electronics-stub