LOOKING FOR GOLDSCAN 4 Schematic.

[Orbit]

Those resistors are used for clock control, with them the detector becomes mobile and no longer static, but loses some of its sensitivity.

[Xtrem]

Hello Ivconic ,could you do a test using a magnet ?

[ivconic]

Hello Ivconic ,could you do a test using a magnet ?

Weird request... but ok!
I have a couple of small neodymium magnets (from a hard drive) in the workshop.
It detects them normally like any metal.

[ivconic]

I noticed an interesting thing.
There is a so-called "sweet spot" on the GEB potentiometer, when in All Metal mode it sees iron very poorly and sees all the previously mentioned "targets" (Antoninianus, Sestercius and bronze buckle) very well.
That's already something! Usable!
...
Ok, I've had a Minelab FT16000, a Minelab GP3000 over the years, worked a few hours with a GPX5000...
FT16000 is not PI but has very similar "discrimination" behavior to GP and GPX.
Probably those detectors make a big difference on Australian soil in the search for native gold and nuggets.
And they probably make a big difference in other geographic locations on the planet as well; where the soils are similar in composition and the same desired targets are.
But with me on my soils where I am exclusively looking for ancient Roman & Byzantine finds... those detectors showed decent depths but very unreliable and weak discriminations.
Often very unreliable, weak and often counterproductive because in some cases a lot of garbage is dug with them.
With this comment, I do not in the least want to reduce the quality and usefulness of those detectors, on the contrary.
But with all that in mind, now as I experiment with this diy GS4; I seem to have gotten the exact same thing.
Ok, as for the depths, I can't say anything definitive about that. Until I make a bigger coil.
And probably a better coil.
The GS4 will obviously work with different coil inductances.
As for the resistance; it is certainly better to have a slightly higher coil resistance due to less heating of the mosfet and damper resistor.
Currently it is about 18cm coil, 0.43mH / 2.9 ohms.
The consumption of the detector is about 200mA without audio response and about 220mA with the strongest audio response.
"Depths" on the mentioned targets in the air are not satisfactory.
It is obvious that a larger coil is needed.
And if the "depths" were twice as are now; I would say that is very good. I'd call all of this a success.
But with these "depths" this is still not a success. And I would not take such a detector with me to the field in search.
What is still very satisfying right now is the sensitivity to very small targets. A very big improvement compared to the other PI detectors I've made so far.
So what to say? The story is not over yet. I need to make a bigger and better coil and see what the best I can achieve.

[ivconic]

There are many (too many) topics about the GS4 on the forum!
It's hard to find it all, read it...
Does anyone remember what Eric Foster personally advised about coil making?
And did he ever mention the depths reached?
I would be grateful if someone knows and writes about it or points to a topic and a post about it.

[pito]

https://docshare.tips/fast-coil_5750...61d8b4aa7.html
UgjfpPkxgNVAh3gCoAEC = pay attention @ 1:12 you can see what kind wire they are using

[ivconic]

I know Joseph, I have that article for quite some time.

[Carl-NC]

I noticed an interesting thing.
There is a so-called "sweet spot" on the GEB potentiometer, when in All Metal mode it sees iron very poorly and sees all the previously mentioned "targets" (Antoninianus, Sestercius and bronze buckle) very well.
That's already something! Usable!

GEB should not do anything in AM mode. But in GEB mode, you can skew the GEB setting to where it just knocks out nails and usually it will see more good high conductors because the target hole is moved higher. However, it is no longer ground balanced so you may have a strong ground response.

The way ML does discrimination is to look at the turn-on response, and this only works when using DD (IB) coils. And it is only effective for shallower iron, deep iron will fool it, as it does many detectors. This requires adding at least one more channel.

200mA seems a bit weak to me, the TDI (and I assume the GS5) runs at about 500mA. Either your pulse width is low, pulse period too high, or coil inductance too high, or a combination. But even doubling the power consumption won't double your depth. And unless you are using a really small coil, a bigger coil won't double it, either. Might help to post all your timing numbers.

[pito]

Reduced range is because of the mixing two channels.= increase gain of U13 A ?
Add in parallel to R55 a 10k resistor.

[Orbit]

TDI sl frequency 2.7khz to 3khz gs 4, 400hz or something more I forgot a little but mostly it has an effect on consumption also gs 5 has similar consumption as TDI..The interval between TX samples and the pause is much longer with gs 4.

[Orbit]

Hi Karl. I'm a bit confused.. About penetrating through the ground. What do you think is the best method Unipolar like tdi bipolar like Gpz 7000 THS method or more burst pluses in delivery? Or does it not make much difference?

[pito]

The consumption of the detector is about 200mA without audio response = and with coil and no coil ?
pulse width and frequency ?

[ivconic]

GEB should not do anything in AM mode. But in GEB mode, you can skew the GEB setting to where it just knocks out nails and usually it will see more good high conductors because the target hole is moved higher. However, it is no longer ground balanced so you may have a strong ground response.

The way ML does discrimination is to look at the turn-on response, and this only works when using DD (IB) coils. And it is only effective for shallower iron, deep iron will fool it, as it does many detectors. This requires adding at least one more channel.

200mA seems a bit weak to me, the TDI (and I assume the GS5) runs at about 500mA. Either your pulse width is low, pulse period too high, or coil inductance too high, or a combination. But even doubling the power consumption won't double your depth. And unless you are using a really small coil, a bigger coil won't double it, either. Might help to post all your timing numbers.

Yes, the way the toggle is defined is a bit illogical.
"Off" is "All Metal mode" and "All Metal mode" is actually GEB mode.
I talk about "GEB" mode all the time but I respect how it is defined on the schematic.



"...Might help to post all your timing numbers...."

Would like to, but don't know how to do that with 2-channel analog oscilloscope.
TX pulse width seem to me too short, I "hunted" it on the oscilloscope last night and tried to adjust a bit wider on display, tough.

[Orbit]

Пошто ми је минелаб метода дискриминације позната... Микрона паметни пулсни хибридни детектор који се овде рекламира наводи на закључак да само његов пулсни предајник и ВЛФ обрада наводно имају дискриминацију до максималне дубине?The rx coil has a large inductance like the vlf tx coil has a capacitor in it and the inductance could not be measured, what is your opinion?

[ivconic]

The consumption of the detector is about 200mA without audio response = and with coil and no coil ?
pulse width and frequency ?

Of course with coil. PW can't tell by now, 550pps (Hz).