[Scott Harden] has been working through a design for a variable inductor to use as a PTO, or permeability tuned oscillator. What you see above is the most recent fruit of these efforts. The variable ...

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 size of the ...

VARIABLE condensers are now so commonly employed in radio receivers to tune circuits including a constant inductance that the use, some years ago, of variable inductances or variometers with fixed ...

Varactor (or “varicap”) diodes are used primarily in radio-frequency (RF) circuits to provide a capacitance that can be varied by changing the applied voltage. These types of diodes often are used for ...

While LCR meters are readily available at reasonable cost, they do not measure the Q of an inductor. This circuit enables you to measure the Q of inductors with the aid of an RF signal generator. A ...

Superheterodyne receivers have been mass-produced since around 1924, but for reasons of cost did not become successful until the 1930s. Before the second world war other, simpler receiver technologies ...

Noel Maginnity is a consultant in Carterton, New Zealand. An alternative audio program input is often required at a medium-wave transmission site. During STL maintenance or if the STL fails, it is ...