Building a Metal Detector

[jap]

re

Hi RelicHunter88
re:This question normal, all the normal inexperienced asked him and do not ask other ,do not understand the answer and This is normal to --------- accommodate the story is not as large as the coil can go deeper--Especially in VLF And not in the case PI.
I hope reading may well protect against this frequent question the - ******I hope not to repeat this frequent question******
-----------------------------------
where!!!!!!!specific coils coil of 3 ft, a detector made for 10 inch coils, will detect targets at 18 - 15 ft depth
j.

[RelicHunter88]

I mean: if i buy a detector with a 10 inch coil, and i replace the 10 inch coil with a 3 ft coil, will the detector be able to work and detect in the depth a 3 ft coil would normally detect?
Or would i need a detector made for 3 ft coils?

[jap]

One more question.

If a detector comes from the factory with a coil of certain diameter, let us say 10 inches, does this mea that the detector works better with coils of this diameter?

If we put a larger coil to a detector, will this make a detector work worse?
Of course a larger coil will be less sensitive, but can the detector work well with a larger coil?
For example, with a coil of 3 ft, a detector made for 10 inch coils, will detect targets at 18 - 15 ft depth, or worse?

where the coil of 3 ft?

[Davor]

as long as your Tx and Rx inductivities and resistances are within the tolerances for the concept you are building - it will be the same.
Some people do build large frames to house even larger coils, so why not.
Counter-question: are you sure you will dig when you detect something that deep?

[Funfinder]

jap wrote:
> do not understand the answer

We do not understand your answer because this is a total disaster.
Try to explain your knowledge on a more technical describtion basis.
This is not the Oracle of Delphi here where we have to assume
what meaning a saying could have or could not have, even if its
the answer to a person of Greece.


relichunter,
if the used transmission power ist too weak and if the
detection circuit has no good signal range scale you
will find nothing with a large coil!

Connecting a cheap ferritecoil pinpointer to a 50cm coil
will not give you 1meter of depth detection, even if you
are using 500 windings.

Gaining depth also has to do with the distance of the coils.

The Garrett GTI 2500 works with a small but also with the
special "2 box" deep coil. The Nexus uses large oo coils
that have more distance for better depth.


Thank you for the additional info and don't dig out
stuff to blow away the brave greek country-leaders!

[RelicHunter88]

jap, it is ok, i have trouble to understand you sometimes, probably we are getting a little "lost in the translation". Anyway, i know that as non-native speaker i cannot say what exactly i want to say sometimes...

Funfinder, we are talking abut "war weapons"...
If we find some all muskets, you can come here one weekend and then we can start a revolution with these muskets... These are as much dangerous as ICBMs... Of course they have to be regulated...


Back on topic.


I prefer to use a little bit "extreme" examples, in that case a coil 3 ft in diameter, because if i learn that a detector will work with one of those, then other smaller coils, will be covered in one answer. That way i do not ask now about a coil 1 ft in diameter, later about a coil 2 ft in diameter and later about a coil 3 ft in diameter. If a coil that large does not work, an answer with some detail about "why" and "how", will be sufficient.

I just want to know more about coils.
Also i need these info to design a coil for the detector i will build.
King Cobra came from the factory with a 8 inch coil. If it cannot support larger coils, then we have a little problem. I do not speak about 3 ft coils (for now ) but a coil about 1 ft.

So, the way i understand it, most detectors will work with larger or smaller coils, but if i need to use a relatively large coil, let us say, 3 ft, i will probably need another detector. But if i want use a coil 1 ft in diameter, it will most probably work.

[Qiaozhi]

So, the way i understand it, most detectors will work with larger or smaller coils, but if i need to use a relatively large coil, let us say, 3 ft, i will probably need another detector. But if i want use a coil 1 ft in diameter, it will most probably work.

The standard coil supplied by the factory is chosen as a general purpose size for that detector. You can fit a larger coil (say, 12" diameter) in order to find deeper targets, although the extra depth will not be dramatic. It will be less sensitive to small targets, and less able to separate out individual targets. For trashy areas, use a smaller coil. Large 3' diameter coils can only really be used with a non-motion detector, and most commonly with pulse-induction.

[RelicHunter88]

Interesting.
Thanks fro explaining.

[Funfinder]

Ehm, RelicHunter88,
what is it that you wanna say with "musket"?

Those have not much to do with the second world war -
they are pretty harmless. But for this kind of stuff you have to find
battlefields from before the 20th century.
btw. some relics from the first worldwar are still more dangerous
as from the 2nd. Alot "dirty" stuff has been used there.


The 8'' (20cm) Cobra coil is too small for your purposes.
Yesterday I was hunting with the Blisstool with 28cm coil
and even that one is too small for larger areas.

You should built a coil of 35-40cm for relics minimum!


Concerning the coil size depth relation below you can see the
approximate depth tests with new objects of the Jeohunter.

There is no coin distance for standard and large coil but I have
both of them and a canadian silver dollar is detectable at ca.
30-40cm with both of them!

I also found an 1cm button and 1.5cm coins with the standard
coil - at 5-10cm depth. And a 45x35cm Alu-case was detectable
in air from 2m @ 100% sensitivity but buried it will be ca. 1,3 m
@ 80% sensitivity.

Below you can see that the real depth advantage for the 1m coil
starts for objects of ca. 20x20 to 30x30cm.

But for investigating a huge area in a short time
the 1m coil is very useful for 5cm finds and larger.

War-sites usually also are very extensive and the relics are mostly
larger than 3cm so the best coil size would be from 35 to 60cm.

The doubled amount of coil-area (200%) gives ca. 50% more
depth than before if the target is large enough.
Plus you only need the half amount of time and sweep work.

[RelicHunter88]

When i say musket, i mean musket.

These weapons shown in photo, are considered dangerous war weapons in my country. Old, yes, but someone might star a revolution with them, politicians are afraid of them... You should see how the relatives of those who fought in 1821 revolution, Balkan Wars, etc. and have inherited their great-grandparent rifle are treated. Government is trying to get rid of these weapons with any given chance. Basically the do the same for any weapon no matter what era is it from.

At the same time, you can buy illegally an AK for 300€. Almost every little criminal has an AK or a Tokarev T33. What can police do with the standard issued 9mm USPs?
And citizens cannot really use weapons for self-defence...

Anyway. Seriously, without jokes, you need permit to collect muskets, musket balls, etc. Even if you do not need for musket balls, better get the license. It covers all weapons and ordnance (exept explosives, incendiaries, etc.) and also swords, daggers and other things.


As for the coils, i do plan on building a coils somewhere 35 - 45 cms and also a smaller, about 20 cms for very tiny metal objects near the surface. I have not decided yet...

[Funfinder]

Thx for the musket info and picture, RelicHunter88.

Treasurehunters are some kind of modern "underground"-pirates
so you also could find or collect some of the following stuff:

http://www.thepirateking.com/historical/flintlock.htm
http://www.thepirateking.com/historical/grenadoe.htm

by the way I could provide you with some musket-balls
but first you have to bring them back in good shape and
don't confuse 'em with candy-drops - could be unhealthy.


I think the law in Greece is somekind "european nation standard"
which is not that bad - disarming the population, especially from
fireweapons, leads to much less acts of capital crime and murder.

Just look at the USA and how many people there get killed each
day just because of the so called "big freedom for selfdefence"
so that any little Wannabe-Rambo can shoot around like hell.

At some Nighlife-Quarters in Europe they even have forbidden
knifes and glass-bottles to reduce acts of violence.


You know already when your treasure hunt will really start?
In 2 weeks, in 2 months, in a half year?

Apropos "treasure" hunt:
I'm watching Balkanika Music Television on Hellas Sat 39°E
and they show also alot really fantastic greek pop songs.
You know Giouli Asimakopoulou and Nikki Ponte?
Are those from Athens? If so, I could check out what they
are doing the whole day (and night ), visit you and support
you personally. I could travel via Bulgaria, buy a detector
there for you and if you don't have to work all day long
we can make some cool treasure hunting adventure trips.

[RelicHunter88]

Funfinder, if someone hears you he will thing that you want to come here to execute "Black Operations"...
While you are interested only in hot girls and a little bit treasure hunting...

Well, most celebrities live in Athens, but Athens is very large. Now, if they do some appearances in a store, bouzoukia kind of thing, then you can come and see them and get an autograph too.

I am not interest in this lifestyle, i prefer to stay home, listening Mozart and soldering PCBs...
But if you want some tips on how to meet Greek celebrities in Greece, i can give you some.


Anyway, i have an update for the detector coming, will post when i fix a technical problem.


Oh, and gun control does not work. In Greece you can find easily AKs (lots of them) Tokarevs and even RPGs.
It just makes the law abiding citizens more easy victims. Criminals will get their weapons anyway...

[RelicHunter88]

UPDATE

THE COBRA HAS ARRIVED

[jap]

Hi RelicHunter88
To the second step with success.
best time
j

[RelicHunter88]

Thank you very much, jap!