Confusion regarding LC tank circuit

[medical-nerd]

Hiya

I've been looking at LC tank circuits and have become confused.

As I understand it when the reactance of the inductor and capacitor are the same it behaves as an open circuit for AC signals.
Is this the same as when it is in resonance, if so how can it act as a tuner for rf signals?

Also can a DIP meter be used to find the resonant frequency if the inductor is using a toroid core, I thought the magnetic field was confined in these.
If a DIP meter can be used, what orientation should its coil be in relation to the toroid?

Cheers

[w2aew]

The impedance of an parallel LC circuit at resonance looks like a high impedance (open), but the impedance of a series LC circuit looks like a short at resonance.  Here are a few videos I did on LC circuits and resonance:








And here's a video I did on the DIP meter.  For toroidal inductors, try orienting the dip meter coil so that it's turns are parallel to turns on the toroid along the outer perimeter, you should be able to couple sufficient energy for it to work:

[medical-nerd]

Many thanks w2aew for your informative videos, you have made resonance of a parallel LC tank circuit much clearer to me.

So as I understand it, when there is an rf signal with a frequency that matches the resonant frequency of the parallel LC  tank circuit, the circuit is open to ac signals so maximum signal is passed, rather than be shorted to earth.

Using a variable capacitor changes the resonant frequency, so allowing different input frequencies to be selected.

Is this correct?

Does a regenerative receiver feedback the output of/to the parallel LC tank circuit so making it oscillate?

What coil have you attached to your frequency counter to check the frequency of the DIP meter? Do you use an amplifier for picking up the signal?

Cheers