3 dB down and coil Q VS bandwidth

[dbanner]

I would use the same coil paramters and just pick an arbitrary number for the Rx freq. let us say 6kHz, then I would de-tune the tX until I get the 20 phase offset. See what that Tx frequency would be, and test out the detector. I would not be surprised if it ended up being some fifth or seventh harmonic related to some scale. It would seem that phases and scales are also related.
The tone might have to be modified by use of a stand alone audio chopper, but all this is do-able.

[Nandor]

That was the thing I was thinking about, the 5th harmonic could not get the proper 20 degree.
I did the audio mod once with 555 and with TL071 but they were weaker than the original.

[dbanner]

All this musical note stuff was an attempt to see some clarity on sympathatic resonant frequencies, and how it might relate, if at all, to Tx and Rx resonances.
But it may not matter at all.
What is murky area for me is the Q and bandwidth of the Rx coil, and where the Tx off resonance point is set in relation to f1 and f2 (3dB down points below and above the center frequency).
This obviously reduces the overall sensitivity of the Rx coil, but perhaps our goal here is to be "shifted" away from balance by the presence of a metal. Then appears the signal of the Tx in the Rx loop.(Due to the inductive coupling of the Tx and Rx)
I need to read some of the threads dealing with this subject matter, I need some more information. I have a feeling that this topic can take exhaustive research and actual experiments to compile reliable data on the science of search loops.
The name Rx coil is a bit misleading as the reciever coil is nothing more than an inductively coupled coil in balance. So by disturbing its balance, energy from the primary coil (TX) is coupled to the Rx coil. So the Rx bandwidth might be entirely irrelevant here. What matters here is strong coupling. And perhaps the Q of the Tx.
I leave matters here for now.

[bbsailor]

All this musical note stuff was an attempt to see some clarity on sympathatic resonant frequencies, and how it might relate, if at all, to Tx and Rx resonances.
But it may not matter at all.
What is murky area for me is the Q and bandwidth of the Rx coil, and where the Tx off resonance point is set in relation to f1 and f2 (3dB down points below and above the center frequency).
This obviously reduces the overall sensitivity of the Rx coil, but perhaps our goal here is to be "shifted" away from balance by the presence of a metal. Then appears the signal of the Tx in the Rx loop.(Due to the inductive coupling of the Tx and Rx)
I need to read some of the threads dealing with this subject matter, I need some more information. I have a feeling that this topic can take exhaustive research and actual experiments to compile reliable data on the science of search loops.
The name Rx coil is a bit misleading as the reciever coil is nothing more than an inductively coupled coil in balance. So by disturbing its balance, energy from the primary coil (TX) is coupled to the Rx coil. So the Rx bandwidth might be entirely irrelevant here. What matters here is strong coupling. And perhaps the Q of the Tx.
I leave matters here for now.

My previous post was to only differentiate what the ear finds pleasant but in inductivity coupled coils the efficiency of the coupling at the desired frequency is what matters most. When efficiently damping the TX coil and the RX coil you may find that the coil wire is retaining some energy or noise that prevents you from detecting those small targets at the optimal distance. Here is where coil design techniques, coil wire size and type, and balancing techniques between coils can make a difference. External noise in populated areas is different from noise in remote areas, so consider your objectives.

In my previous post I was only trying share my understand of musical intervals relative to human hearing with intervals that might relate to metal detecting being one half or twice the frequency of detecting versus the outside noise frequency.

Joseph J. Rogowski