LOOKING FOR GOLDSCAN 4 Schematic.

[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?

[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.

[pito]

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

[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.

[ivconic]

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

[pito]

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

[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.

[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]

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.

[Xtrem]

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

[Orbit]

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

[ivconic]

In most cases, I tend to believe that, there is no bad intention.
But is more likely about the fact that we are all living human beings of flesh and blood, whoever works makes mistakes.
Only those who do nothing do not make mistakes.
In this case, I am even grateful for those mistakes, because that way I was forced to go deeper into the essence of the project and to understand things better.
If there were no errors, I would have simply replicated that detector and would not have been too keen on going into details.
Because by nature I am very lazy and inert. And I'm at an age when I'm increasingly losing motivation for further "endeavors"...

[ZOUjiarui]

People always like to release pcb without inspection

[ivconic]

Alex did a great job!
Obvious.
I went a step further and added a ground plane to his pcb design.
In order to improve the S/N ratio even more.
I tried to make sure there were no mistakes, but I can't guarantee that I didn't make at least one.
This should be checked though.
But I like this pcb design a lot more and I think it is a better choice for those who want to make it.
...
Alex's choice to put all resistances on the bottom layer is a particularly good move!
Makes a lot of sense!
Because resistances are certain noise generators, depending on where they are located and the role they play.
An additional good thing is because the SMD 1206 resistors are smaller in size, smaller "antennas" that emit noise...
but the 1206's are large enough to easily solder to the solder pads.
A very intelligent choice indeed!
It reminds me of my way of thinking when designing a pcb.
A very smart move, which I liked right away.
I also like the footprints for most of the components better than Eric's choice.
Eric used 2.5mm for capacitors and 5mm for resistors!!!
More than once I mentioned Eric's name in the process of soldering components in that excruciating way!

[ivconic]

I ordered several types of pcb in the same package.
The original GS4 design, then Alex's pcb design, which I like better, but I haven't decided to build on that pcb right away, because of the SMD resistors on the bottom, until I get them all...
and a couple more pcbs for some of my other devices .
JLPcb minimum quantity is 5 pieces, so I had to order 5 of each.
I don't have the conditions to ship abroad without it all making sense in terms of shipping costs, so don't ask me for a pcb.
Because it doesn't make sense.
It is much cheaper to order directly from JLPcb yourself and with the Fedex shipping method, it ends up being cheap and very fast, within a maximum of 10 days it arrives at your home address.