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 ...

[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 ...

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 ...