White 3900D

[kt315]

Koliaj deleted a cap on RX and got same result. you have to learn russian and russians forum.
i had gave a link. find me out phase shift mentioned in the patent.

https://www.youtube.com/watch?v=8Hs78GXUkFE

what type coils you see in this video? STANDART 6.59Khz. NOT 6B COIL. so your point is a fantazy.

[kt315]

15 maxima blue coil. on RX part we see 33nF cap.

[dbanner]

Koliaj deleted a cap on RX and got same result. you have to learn russian and russians forum.
i had gave a link. find me out phase shift mentioned in the patent.

https://www.youtube.com/watch?v=8Hs78GXUkFE

what type coils you see in this video? STANDART 6.59Khz. NOT 6B COIL. so your point is a fantazy.

A few points here.

Firstly, the patent US4293816 describes the physical construction of the concentric coplanar coil design, along with the theory of balancing, due to the buck(feedback) coil arrangement. It does not mention signal phase because that was not the intention of the patent. It's intention was to demonstrate the balancing of a coil so constructed, with minimum residual voltage, by means of a feedback coil.

Secondly, it is mentioned in the patent that the operating frequency of the oscillator is 5.125kHz, and thus the Tx coil is tuned by means of a parallel capacitor for resonance of 5.125kHz of the oscillating Tx circuit.

Thirdly, the Rx coil in the patent, based on Qiaozhi's coil calculator (Brooke's equation), has an inductance of around 11.8mH.
If you tune this Rx coil with the 27nF cap stipulated in the patent, you get a Rx coil resonance of 8.9Khz. Right away you see there is "off resonance between the Tx and Rx coils " when coils are balanced. THIS WILL RESULT IN A PHASE SHIFT of the Rx voltage with respect to the Tx. So a phase shift, although not expressly stated, is implied.

Lastly, I believe there are only two conditions which result in zero phase shift, these are 1: when Rx is non-resonant, and 2: when Rx and Tx are at equal or "full" resonance.

[kt315]

OKey. MAIN ISSUE THERE IS NOT THE PHASE SHIFT MENTIONED IN THE PATENT.
GREAT DISCOVERY AMIGO.

second issue. can you give me a patent of whites WITH/ON coil phase shift?

[dbanner]

OKey. MAIN ISSUE THERE IS NOT THE PHASE SHIFT MENTIONED IN THE PATENT.
GREAT DISCOVERY AMIGO.

second issue. can you give me a patent of whites WITH/ON coil phase shift?

Simple amigo, just measure on oscilloscope the Rx/Tx waveforms of a Whites bluemax coil with your famous coil tester. Tell us if you see a residual phase shift.

[kt315]

thats good. i did videos with 9.5 xlt coil, but youtube deleted my channel with all videos.
i sure showed HOW phase shift changing just on very small moving, 5mm...1cm..., of the balance loop. you have to see that!
very big range of the phase. i still have a coil that seems unbalanced but it is working great -!
so deal is not in phase shift, but IN RIGHT PHASE SHIFT'S AND AMPLITUDE REACTION ON A METALL, that i had told many times.

[dbanner]

One thing I noted, the so called "balanced" coils" in the patent states coils are balanced to the nearest zero condition. But this might not be so if one has a residual phase shift in mind, it could be slightly to the left or right of this minimum.

But what the hell do I know. All this is from reading the stuff, and my reasoning could be flawed.

Experts can say more to elucidate the topic.

[kt315]

look on 3:09 https://www.youtube.com/watch?v=LPth6lBBGUE
she does not balance the coil. she just checks THE RIGHT REACTION ON THE METALL - moving of RX phase and encreasing of RX signal amplitude.

again - REACTION. look attentionally the video.

[dbanner]

Another way of looking at the residual phase offset at so called "Null", is to think of a metal target taking the balance of the Rx further away from its "null", resulting in a phase shift, the degree to which depends on the type of metal target.
If you move that tiny fine null loop around, you also see a shifting of the phase. The more "off resonance", the greater degree of shifting.????? I don't know.

The balanced coil with an initial phase offset is meant set up the calibration points from which the detector circuitry takes its gb and discrimination. But it still does not answer the question of why having "off resonance" coil.

I noticed there is matter of temperature effects on the sensitivity and stability of the loop.
Maybe I try hobby of brass rubbing. Seems much easier.

[Nandor]

thats good. i did videos with 9.5 xlt coil, but youtube deleted my channel with all videos.
i sure showed HOW phase shift changing just on very small moving, 5mm...1cm..., of the balance loop. you have to see that!
very big range of the phase. i still have a coil that seems unbalanced but it is working great -!
so deal is not in phase shift, but IN RIGHT PHASE SHIFT'S AND AMPLITUDE REACTION ON A METALL, that i had told many times.

Thanks for sharing it, I've seen it on youtube. So bad that they deleted it Sinclairuser. It was a nice demonstration!

[kt315]

thank you Nandor. who wanted had see the videos.

now another coil. 8inch blue max. on RX part we see 56nF cap.

[dbanner]

She does not balance the coil.....


The coils are very close to balance simply by knowing number of turns, wire size feedback turns etc,etc, in the manufacturing process.
They make their coils to very precise quality control standards, so that in the end, the inductive balance is there merely through controlling the coil making process. The trimmers take care of the rest. That's my assumption.

[waltr]

The best paper I have seen on VLF Coil resonance and has been posted here on Geotech is:
VLF coils Kostin.pdf

Very good read.

[kt315]

Kostin reseached that
- a reaction on unferrous at first moment is just phase shift, then after at secondary is phase shift and amplitude
- a reaction on ferrous at first and later is phase shift and amplitude, together.
from that you see why VLF two-channel classic two-comparator schematic has low sensitivity on unferrous and big sensitivity
on ferrous. because at first stage when un-ferrous channel already turns up, second all-metal channel is still in turn off state.
NO signal, no reaction.

(i do not use 'X reactive' and 'conductive R' conceptions here)

[dbanner]

Kostin document is a very interesting read, I appreciate how he tried to lay an empirical basis for "off resonance" coils. The very interesting conclusions come at the end of the document, especially the temp. data.

Not sure I understand everything, but like I said before, IB coils are not necessarily balanced for minumum residual voltage on Rx, but rather close to such, and is the case with "off resonance", there appears to be an inherent phase angle which coincides with the rest of the circuitry parameters, otherwise the min/max discrim settings don't work correctly. Beyond that, things become a little fuzzy for me.