Variable capacitors may be useful, but the air gap that provides their capacitance is their greatest weakness. Rather than deal with the poor dielectric properties of air, some high-end variable ...

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 ...