Competition!

[ivconic]

However, I would leave such suggestions to the professionals who are paid to do so.
And considering that we are on a forum that mainly deals with hobbies; I would rather devote myself only to the hobby.
"...This triangle has been around since the invention of the rock. Achieving all three is not possible..."
Well...
Self-centered conformism is something that follows these forums and is unfortunately present everywhere.
"Mine is bigger than yours" is actually what it dates back to the invention of the rock times.
Achieving all three is possible, of course.
When I say this, I first have in mind the ultimate point of the metal detector, which is that the detector finds a find in the real conditions.
I don't care if the detector seems too complicated, too profane, too advanced and untouchable... it doesn't interest me or motivate me in the least.
The only thing I'm interested in is that the detector works so that I'm satisfied with it when I go out on a real ancient site where there are real ancient finds, artifacts.
To this day I am still impressed with the way the Fisher 1265/66 was conceived and built. To this day, the same machine gives me great pleasure in working.
To this day it is the same pleasure with the Musketeer, Cscope 1220B, CZ5, ML Explorer...
Nothing has changed. I haven't changed my mind.
Playing with such projects is an endless pleasure.
And the motivation is in getting to know better how these machines work and trying to improve even by 1% in the quality of work.
Of course, we're talking about the hobby here all the time, right?

[moodz]

Is that the point of the hobby?
Is that the solution for most?
Aren't there already armies of professionals in major companies working on it?
Aren't there already such attempts on the forum?
Carl described the fate of such attempts very well.
And we already have "successful" results on the market in mass quantities.

The point of the hobby varies from person to person as you already pointed out. Some want to put up ideas, some want to design, some want to just build to a recipe, some want to buy a built unit. Some are just lurkers etc etc.
There are professionals working on it both private and commercial ... their motives vary.

In 1991 a company called RSA put out a competition to "break" their crypto security products by factoring large prime related numbers and they offered cash prizes for varying degrees of complexity.
This was clearly a competition and despite the cash prizes was a challenge to many and would have been taken up even if no cash was involved.
The challenges were solved faster than RSA anticipated and new ways of factoring large numbers were discovered.

So if you want people to be mofivated you have to challenge them. Building the simplest detector is not much of a challenge ..

It would have to be something like if you can build a detector that can resolve a gold coin from an iron nail at 1 meter then the prize is $10,000 or a case of beer etc.

I am sure someone could lobby the MD industry to provide rewards for a competition.

moodz

[ivconic]

10-15 years earlier Tony Tinkerer and I had exchanged several emails on similar topics.
There are EU investment funds that encourage and finance advanced ideas and projects on demining crisis areas.
I hope Tony is here and well, I really appreciate the man and he is very good to work with.
When I talk about such funds, I am talking about figures like 10 million euros.
The money is ready, what's stopping you? And you and the others?
There are places, times and conditions for everything. Everyone can valorize their work.
Or at least check the valuation by others.
10 million euros is, I hope, enough motivation for advanced thinkers?
I still know where I belong, and that's what I told Tony then.
I prefer to leave lofty goals to the ambitious.
I am modest and my goals are amateurish and modest.
But I find infinite pleasure in them.
Hats off for what you said though, strong motivation is the way to progress.

[ivconic]

Life is full of coincidences!
While I was writing the last post, the postman called, bringing me a "new" toy for the long winter days.
I talk about it all the time. It's a hobby and it's motivation. Because this machine is a mess, there will be a lot of work to fix it.
And of course; project analysis, the way things were done there, learning from old knowledge.
It's one thing when you just look at a schematic that someone published, it's another thing when you have a living thing in front of you.
Many good things are "buried" in such old machines and left to be forgotten.
We give up that treasure of knowledge too easily, we rush too quickly into "new" things that are just a pale copy of the old knowledge.
That's why metal detectors are specific, different from other technologies, real progress can only be expressed in a few parts per thousand for a period of 30-40 years.
Of course, taking into account only vital and useful functions, without a bunch of irrelevant "whistle and bells"...
The opposite of, say, personal computer technology. 20 years ago I was impressed with a 150Mhz machine... today I have an 8 core processor and I'm not impressed one bit...
Of course, this is just my opinion. It would be unnatural for everyone else to agree with it.

[moodz]

...this is your bench after testing that for a while ...it needs 6 batts ???

[Tinkerer]

... here's my entry with the optional "range extender and back saver" attachment.

needs no battery.
you can swing all day !

Easily resolves iron and ferrites from gold and other non ferrous objects.






Seriously though Carl is right !

I would think that a division of labour might be worth a try ... form a "virtual enterprise" to produce new designs.

Idea people ( ideas for detectors and features )
Engineering people ( doability and proof on paper )
Backroom people ( construct proof of concept )
Document people ( writeups / schematic design /parts spec / how it works descriptions etc )
Maker people ( PCB / housing / coil making etc )
Tester people ( test prototypes / give feedback and reports )
End user people ( customer use and satisfaction )

Feedback paths between different groups ... decisions made by voting concensus and tiebreaker decision maker appointed.


moodz

as a footnote ...

From 1851 to 1896 the Victorian Mines Department reported that a total of 61,034,682 oz (1,898,391 kg) of gold was mined in Victoria. Gold was first discovered in Australia on 15 February 1823, by assistant surveyor James McBrien, at Fish River, between Rydal and Bathurst (in New South Wales).
This gold was all found just by LOOKING. ( not even a magnet )

I agree on the division of labor.
Teamwork between a few people, where each one contributes with what he is doing best.
Real progress can be made this way in the shortest possible time.

There are many new and different ways to try, but if a single person takes years to try one new idea, it takes a lifetime to try only a fraction of the possibilities.

There are quite a few ideas that have been presented on this forum. How about some teamwork in developing these ideas? AMX for example. There are several other ideas too.
Too challenging?
Too much work?

A bad craftsman blames his tools....A good one always finds a solution.

[ivconic]

...this is your bench after testing that for a while ...it needs 6 batts ???...

Oh yeah, the power supply is pointless on those models.
But I had a model "5" some time ago and I found a good solution by experimenting.
A stepup converter that increases the voltage from one battery to (minimum) 32V, then an additional voltage regulator to 9v and it all works perfectly correctly.
I've already tried that, so I'll do the same on this model.
Otherwise, it is really impractical to put so many batteries in the detector. But that is from a time when there was clearly no saving.
And IMHO, there is a much more important reason for that; S/N ratio. Various voltage regulators are known to be a significant source of noise.
The ideal power supply is directly from batteries without regulation. But the downside is the voltage drop on such a battery...
In any case, the remark is valid.
A step-up "by definition" can be a source of noise.
But if the conversion works at a high frequency, there is less chance that it will significantly interfere with the operation of the detector.
I didn't notice any deterioration on the "5" model. We'll see what happens with this one.

[ivconic]

I agree on the division of labor.
Teamwork between a few people, where each one contributes with what he is doing best.
Real progress can be made this way in the shortest possible time.

There are many new and different ways to try, but if a single person takes years to try one new idea, it takes a lifetime to try only a fraction of the possibilities.

There are quite a few ideas that have been presented on this forum. How about some teamwork in developing these ideas? AMX for example. There are several other ideas too.
Too challenging?
Too much work?

A bad craftsman blames his tools....A good one always finds a solution.

To avoid a repeat of the AMX outcome; the facts that I presented in earlier posts should be taken into account in advance.
I agree with Carl's assessment of the 95:5% ratio.
95% of us hobbyists still do not have the conditions to follow those 5% who have the privilege of working with new material and in a modern way.
It is necessary to design a project with "old" material, if possible immediately adopt through-hole as default and always act according to the worst case scenario.
Later, it will all be much easier for those from the 5% who can translate it all into a "modern" and "advanced" style.
For example. opamp, let's put the NE5534 right away, and who has the conditions later; put some "$80" ADxxx opamp. He does not lose anything, in fact he gains.
Resistors... it really annoys me and makes me angry when I see "ga-y" values, like 49.5k... and the like!
I've been doing this for 35 years, so far I've NEVER had a case where my detector worked worse because I put, for example, 47k instead of the "ga-y" value!
I mean... come on people!



Ultra invisible small SMD components, which even picknplace robots struggle with and wear glasses to solder... it's not a necessity... it's just pretentious hogwash!
Etc. I could list a whole day of strong complaints. Because all this is not a hobby and not something that most people can participate in.
Those 5% who can do it all; ok, form a closed club and play to your heart's content. But don't call it a hobby.
I can play here as a very profane and professional expert.
Today it is less expensive and possible.
I do the documents and send JLPcb to put everything together for me.
But that's not the point.
Sooner or later we will want to modify such works or there will be a need for repair... then what?
AMX... Carl immediately burned the first pcb!
I believe he would have had a much easier job if he had chosen through-hole ... or at least 1206 size SMD components.
That's what I'm talking about and those are my objections... otherwise I'm not against progress, but I'd rather leave it to the professionals.

[Op04]

Talk about battery, why not using power bank with power delivery (PD) with type-C decoy via 5.5x2.5mm DC jack, option for 5-9-12-15-20-24-28V from ranging from 22.5W 45W 65W 100W I never try though, don't know is it noisy?

[ivconic]

No need for such a bulky addon.
One single battery and stepup solves the problem and everything can be packed nicely into the existing battery compartment.
But ok, that's an idea too, why not!

[Op04]

No need for such a bulky addon.
One single battery and stepup solves the problem and everything can be packed nicely into the existing battery compartment.
But ok, that's an idea too, why not!

Okay above 30Watt it's quite bulky and only start from 30W possible using above 15 Volt. But it's charging simplicity just by using Type C chargers for smartphone

[bbsailor]

I would like to share another point of view about metal detecting.

1. Search location,
2. target types sought,
3. target time constants sought,
4. coil size,
5. detection method being used,
6. optimization methods to better find desired targets.

While detecting on the beaches in Ocean county and Atlantic county NJ I had to find ways to optimize my detecting effort to find more targets more easily.
1. Choose beaches that are densely populated
2. Choose a coil size that best finds desired targets
3. Use circuits that optimize the signal to noise ratio
4. Observe when the weather conditions result in sand and coins are being thrown up onto the beach
5. Use a half inch square wire mesh to make a 1 foot diameter by 1 foot tall sifting basket to quickly retrieve targets from sand
6. Place a magnet in a small plastic bag with a string attached to throw on the beach when I came upon black sand to see if it is organic or magnetic sand.

Once I understood how PI metal detectors work, I began to appreciate why the TX pulse lasts about 3 coil time constants. The total coil circuit resistance along with the coil inductance will govern the shape of the TX pulse with the current rising to almost horizontal when the TX pulse turns off. This ensures that any currents induced into targets at the initial current turn on have died out at about 3 time constants when the TX pulse turns off and the intended stimulus of the target occurs and then in a mono coil the TX coil becomes the RX coil. The time between the TX turn off and the RX turn on is called delay. The delay is based on how quickly the TX oscillations can be damped so the coil can be in the RX mode. The more capacitance that the coil sees, the lower value the damping resistance needs to be to quickly damp these oscillations. However, during the delay time, the induced eddy currents in the target are decaying and may not be there when the RX coil turn on. This is why I wrote the Fastcoil.pdf article. I set up my workbench with a signal generator and an oscilloscope to measure coil seen capacitance from coil winding capacitance, coil to shield capacitance and any other coil seen capacitance that I could minimize to reduce the delay. Coil to shield capacitance using a single layer of Scotch24 mesh is less than using a solid foil shield.

Being competitive with metal detecting requires an interest in selecting the right detector type and coil size for the desired targets, detecting location and environmental conditions. It also depends on how deeply you are willing to go to optimize your metal detector, what test equipment you have access to, and how deeply you are willing to dive into tinkering with your working metal detector or building one from scratch.

Learn about a concept called dielectric constant of a materiel. Lower is better as it loads the coil with less seen capacitance. Teflon insulation is about 2 while PVC is about 6. Remember, making a hand made coil could take some time but you can apply a low dielectric constant spiral wrap to secure the coil winding as well as provide a good spacer between the coil windings and the Scotch24 shield.

Abstract concepts used for a practical purpose become less abstract once you experience the results and visualize how the pieces finally all fit together.

I came to Geotech1, I researched, I wrote an article and I found some targets.

Joseph J. Rogowski

[ivconic]

I like the post!

[ivconic]

Joseph, it's good to have you here, you rarely appear, you don't write often... but you always write good and useful things.
Maybe this is off topic... I have a dilemma, your opinion would help and mean a lot to me.
I make copies of Pulse Star 2 (analog version). Not that often, maybe once or twice a year. I work with the detector until it is sold.
I am not aggressive about advertising and selling that detector. The initial motive for making it was for personal use.
That's why I didn't bother to establish one and the same coil for it. I usually make a coil from currently available material.
If you've ever seen a PS2 (either analog or digital "Pro" version); you must have noticed that there is a switch for Sample Delay on the front panel, with 4 positions.
Position "1" is the shortest delay. And 90% of the time I use the detector like that. And the coils that I have made so far were generally from 18cm to 42cm in diameter.
Not because I intended it to be; but because I mostly found such coil "cases" (lids made of plastic bins and similar handy material).
With the 18cm coil detector works almost unbelievably well! With such a small coil diameter; the ranges are incredible.
The 18cm coil has an inductance of ~380mH and a resistance of no more than 3 ohms. Damper at it is 680 ohms.
But as I increase the coil diameter; thus the detection results decrease. It's still good, but not as "sensational" as with 18cm.
Some time ago I acquired (from a friend from another country) 3 coil enclosures with 56cm diameter.
And since then I've been trying to make a good coil for those cases/enclosures. Alas... I fail. I tried with wires 1mm, 0.8mm, 0.5mm and now almost with 0.55mm.
I use regular Cu wire. No litz, because I can't find it.
I am "chasing" the inductance of 0.68mH-0.7mH because it is that much on the original PS2 45cm coil. And resistance no higher than 2 ohms.
Apparently, a 0.6mm wire would be suitable, which I don't have now but plan to get.
But even with 0.55mm I got very close specs. But the detection is still not "sensational". But very average.
I have in my place a friend with the original PS2 Pro with a 45cm coil. When I compare; the original works at least 30% better.
And someone recently mentioned to me in a conversation that he knows for sure that the original is wound with litz.
I still don't know the damper value in the original.
But the value of that resistance is not a problem, it will be established by observing the RX signal on oscilloscope and using a "jig" to adjust. (potentiometer and resistor in parallel with the resistor)
Somehow I feel in advance that even with a 0.6mm wire I will not be happy.
I can't get litz. Except me to looking for power cables, but the "channels" in the enclosure are so tight that the PVC litz won't fit there, as many windings as I think I'll need.
Question; would it change anything if I wind bifilar with 0.3mm? Or should I take 4 x 0.15mm? Or similar?
How many wires in the litz are actually necessary to achieve an effect similar to the original coil? (A similar question applies to all ML coils).
What most of us declaratively know; it is that litz is always better than single wire. But few of us understand all aspects of that story.
And so far, I haven't found anywhere that anyone has done experiments with "multi-filar" attempts, not from originally purchased litz, but from hand-prepared wire.
I would like to hear the opinion of someone who knows it much better than I do.
Thanks in advance to you and to anyone else who would know what to say on this topic.

[pito]

[FONT

I have in my place a friend with the original PS2 Pro with a 45cm coil. When I compare; the original works at least 30% better.
\[/FONT]

compare transmitting power your and friend, show a picture of the coil.

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