The wire descending from the antenna goes to the parallel LC resonant circuit consisting of a coil and a variable capacitor, CV. Together they tune in to the desired frequency.

It’s also a parallel LC tuned circuit. That’s where the original ac signal that’s exciting the eddy currents in the “secondary” piece of metal is coming from.

[Thomas] picked up a Marconi TF1245 with dents and dings. We have to admit that we had not heard of a “ circuit magnification meter,” but apparently, this was a thing in the late 1960s and ...

This is a common emitter Colpitts oscillator. R1 and R2 form a voltage divider to provide base bias. the emitter resistor R3 also provides some bias. R4 is the collector resisotr across which the any ...

This Design Idea applies a noveltopology to an oscillator. It usesa series-connected LC (inductive-capacitive)tank circuit to give the circuita higher tuning range than circuitsthat use a parallel-LC ...