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 ...

If you’ve seen a big air-variable capacitor, you may have noticed that some of the plates may have slots cut into them. Why? [Mr Carlson] has the answer in the video below. The short answer: you can ...

The variable capacitor C1 and L1 will constitute the tank circuit which will produce the high frequency signal, the capacitor C1 is variable so that we can produce different frequency signal by ...