Cavity Filters, The Black Art You Have A Chance Of Pursuing

A tuned circuit formed by a capacitor and an inductor is a familiar enough circuit, and it’s understood that it will resonate at a particular frequency. As that frequency increases, so the si…

Siphoning Energy From Power Lines

The discovery and implementation of alternating current revolutionized the entire world little more than a century ago. Without it, we’d all have inefficient, small neighborhood power plants …

Permeability Tuned Oscillators Made Stable With A Glue Stick

For over a century now, radio amateurs have made tuned circuits using a coil of wire and a variable capacitor. In recent decades the supply of variable capacitors has dwindled, as SDR technology ha…

NFC Performance: It’s All In The Antenna

NFC tags are a frequent target for experimentation, whether simply by using an app on a mobile phone to interrogate or write to tags, by incorporating them in projects by means of an off-the-shelf …