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Identifying A Detector


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You are implying I’m smearing good actors with a bad brush. I’m not much for giving the benefit of the doubt in this industry for very good reason. Buy from who you want, but I advise anyone to have a “suspicious nature” when dealing with metal detectors, and especially “treasure hunting” devices. Frankly, it’s hard enough to not get sold a bill of goods from the so-called legitimate operators, touting last years tech as new and improved because it has a new decal and a paint job. If you are wise in this industry, you learn very fast that trust is earned, not given. I may be a slow learner, but I’m old enough to have learned a few things anyway about metal detector companies and the industry as a whole. Am I going to build a legal case for you? No. I’ve got better things to do with my time. And as I said also, I hope the poster got an ok detector. How ok just depends how low the bar is, and whether you think it’s ok to use a detector you’d personally toss in the corner after an hour or two.

I often ask myself to whom and to what end a post is made.  In my case, often a post is aimed at a specific person but even more often it's aimed at the general 'audience', both present and future.  Seldom do I say anything profound or new, and often 90% of posters already 'know' what I say.  It's the other 10% that are my intended audience in those cases.

Another thing I try to be conscious of is the level of knowledge of the person who asks a question.  Speaking to that person's level, including using full words instead of initialisms/acronyms, including a manufacturer's name with the detector, etc.  I've been in the newbie shoes and I remember how confusing and frustrating it can be to learn the lingo, in every area of interest, not just detecting.

Along those altruistic lines I was trying to 'soften the blow' for this new detectorist.  He asked some good questions.  Could he have made a better choice of new detector?  Yes, but from his knowledge of detectors at the time he made his purchase, maybe not.  If he could return the detector now for a full refund, that's one thing.  Otherwise it seems best, IMO, to make the most with what is in hand.  If it works (it seems to from his continuing responses), then using it as a learning tool (and continuing to read here and ask questions) will put him in better position when he's ready to make his next purchase step.  And if in the meantime he decides detecting isn't for him, well, hopefully his investment was minimal and compensated by the knowledge gained.

I'm fully aware that everyone has his/her style of detecting as well as posting.  I do my best to respect all of that as long as I perceive the intentions as honest and non mean-spirited.  (That's >99% of posts here as far as I can tell.  One of the things that make this such a great site.)  I'm also in the tail of the distribution when it comes to correlating an idea or claim with a person.  Sometimes I may go overboard in expecting others to meet my standards there.

Responding to a specific post runs the risk of offending or at least rubbing that poster the wrong way.  Could my response then (and even this one now) have been better made?  Almost assuredly.  Do my posts sometimes come off as 'lectures'?  Probably; I need to work on that.  Condescending?  Hopefully not....  Arrogant or pompous?  I definitely hope not, but there's a fine line between confidence and those attitudes, it seems, and particularly a person's perception of them.  I'm always learning, too, whether it's detecting or communicating.  When I quit learning is when I depart for greener pastures.  No risk of that here, though.  I'm having too much fun for that.

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Welcome to the forum!!!!!

 

I wonder what is the physics behind my Mental Detector showing higher VDI (larger phase shifts I gather) for the same conductive target when the sweep speed is higher?

The detector you have appears to have most of what you need to get started. It is an amazing mix of Garrett and Fisher components. It should give you an inexpensive way to learn about metal detecting.

One of its highlighted features on the King Detector website is its target ID accuracy coupled with a very slow swing rate. Since it appears to have a concentric coil it actually might have fairly good accuracy if you use Steve's earlier suggestion to do a controlled 3 second swing that takes about 2 to 3 seconds to pass the coil over the target with a full right to left swing and a full left to right swing. Full means the entire coil is passed over the target in both directions so if your coil is say 20 cm then you want your swing to be roughly 40 cm in each direction so that the coil has a chance to "see" the target with a fresh start on each swing. Your swing needs to be as level and parallel to the ground and target as possible. If your swing is more like a pendulum and the coil dips at the target and rises on the ends of the swing a lot, the target IDs and tones may change.

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Not a perfect situation by far. Since the original poster has the detector already, it is easy to think just go ahead and use, and see how it goes. The reality is most people find metal detecting (digging trash for pennies) kind of boring, and many give it up after a try or two. This detector can sort out if the poster has any genuine interest in metal detecting, so there is that.

After that though, if I wanted to teach somebody to drive a car, I'd want them using a car that I know works for sure. In my opinion these things may as well be one offs, and no way to know what change was made between this one and the last made. Outfits like First Texas make secret inline changes all the time, and never tell anyone. If that's from somebody like them, I'd not bet on these things being consistent unit to unit. They have no real constraints on what they have to provide, and how it has to perform. They switch front company names almost daily it seems, so building brand reputation is not the goal, ditching bad press is. That in itself says something.

So how do I teach you to detect, if the machine itself is inherently flawed? Do I want the new driver in a car if the brakes don't work?

So to repeat myself mcjtom, I’m not trying to take any shots at you personally, as I'm sure you did the best you could with the situation at hand. Hopefully you can play with each control enough to figure out what it does and does not do (in reality, which might not match manual), which really is how anyone should learn a detector anyway. Use test targets and run controls end to end, and observe results. Best wishes, and good luck. :smile:

 

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Mental Detector , probably a typo error but I love the name !

(My guess is the physics of swing speed would be the opposite , going faster producing less phase shift . But I didn't design these things  )

Either way  I'll echo the above comments , the variably fast vs. slow and constant speed is probably one of if not the reason for the vdi shift.  Maintaining a constant distance (level swing) is another . 

 

 

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Mental Detector , probably a typo error but I love the name !

It's in their marketing 🙂

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Exactly . 

Of course it COULD have been a "too late to change it now  , over budget" thing ,,but I bet we all remember that name..!

 Now watch , he's gonna find a giant treasure with it.  And later we'll find out the design engineer found something that was left behind by ,,,advanced intelligence.😏

May the force be with him .

 

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You should see what they're pulling out of the ground in Thailand. 🤯 But the people I saw were using a GPX. Thailand has temples that predate the pyramids. I'm sure they are off limits but metal detecting is mostly legal there (or not illegal anyway). Jewelry, pottery 5-800 years old, you name it. The detectorist was saying most of the really good stuff is 10-20" plus down tho. 😬 Sounds right to me in a country that probably gets more rain in a week than we get all year. It's not on my bucket list, but it is fascinating.

Well I'm out, thanks heavy hitters for jumping in. 🙂 I'm not up for the deeper stuff yet. 👍 just testing what I know so far.

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Thank you! While I think I understand the idea that consistent, overlapping swings with the coil at constant height, parallel to the ground would produce more stable IDs, I can’t figure out why the ID values increase with higher swing speeds and decrease with slower ones, reproducibly, with the same easy test target, everything else being equal (or close to it)?

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As uncanny as it is, someone from NZ is now selling one of these Mental Detector 3030's second hand on NZ's online marketplace, they claim they used it once for an experiment and now offloading it for $143 NZD.  I wonder if their experiment was to see if it was worth owning 😛

https://www.trademe.co.nz/a/marketplace/business-farming-industry/industrial/manufacturing-metalwork/metal-supplies/listing/3341928819?bof=SQg6hm21

In their photos they show it does come with a manual, so I'm not sure why yours didn't mcjtom, perhaps they forgot to put it in the box? 

1452327315_3030manual.thumb.jpg.7ff4bfd3e512cd628d4e034fd2526544.jpg

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Hi, my detector came with the manual as well (same as on the picture).  I was just looking for more technical information on it in my first post.  Interestingly, I paid an equivalent of about 50 NZD for it in Thailand.  I'm already learning from it and from all the kind comments by more experienced members - so it was a worthy investment for that alone.

p.s. This correlation of swing speed and ID values (the ID values for a surface conductive target clearly and consistently increasing with sweep speed, not necessarily getting more variable) doesn't let me sleep at night - is that unique to the Mental Detector?  Even so, why would the phase shift (which I imagine the IDs use) increase with the faster swings?

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