[Jezan] decided to introduce his son to electronics by building a small crystal radio. These crystal sets have been around for a long time, and make for a great beginner electronics project, but some ...

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 ...

Like all capacitors, variable capacitors are made by placing two sets of metal plates parallel to each other (Fig. 3-1A) separated by a dielectric of air, mica, ceramic, or a vacuum. The difference ...