VLF null and frequency

[profesor]

series resonance low ohms
parallel resonance high ohms.

[waltr]

Probably there is no good, technical, answer as to why the engineer chose a parallel verse a series tank circuit.
Both create a sinusoidal output.

[manhunt47]

If someone has information and can help me, please advise
No one has responded yet

[manhunt47]

Hello to all
I have some questions that I would like to thank for help


In general, there are two Rx coil coupling structures that are:


1) Parallel tank resonance circuit (TGSL and ELDORADO and RAPTOR devices)
2) series Tank resonance circuit (CIBOLA, TEGON and FORTUNE devices)
I've taken photos of these two different structures.


1) What is the difference between the two parallel and serial connection structures in the Rx VLF metal detector coil?
2) Why did TESORO's older machines use parallel tank structures, but used end-of-series tank resonance series?