Radio experimenters often need a variable capacitor to tune their circuits, as the saying goes, for maximum smoke. In decades past these were readily available from almost any scrap radio, but the ...

How do you implement a variable capacitor these days? Mechanical caps are out. That leaves varactors, which work fine but require higher voltages that often are not available, and their response is ...

[Scott Harden] has been working through a design for a variable inductor to use as a PTO, or permeability tuned oscillator. What you see above is the most recent fruit of these efforts. The variable ...

Marked: "Dayton Fan & Motor Co. / Dayton, Ohio, U.S.A. / Day-Fan". A Variable capacitor with six fixed plates and six movable plates. Arrangement of plates permits interleaving of sets of three each, ...