second hand magnetometors?

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phil

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hi guys
i'm new to this game but someone has asked me to research which instruments would be best to find an old, coverd, man made cavern in a clay bank around 1 to 10 meters under ground, from looking on the net it seems magnetometers or resistivety devices would be best but are there any available second hand or for rent in eastern europe?
if any of you folks have advise wht to use and where to get it it would be most appreciated,
thanks
phil
leafmould@hotmail.com
 

cptbil

Bronze Member
Mar 27, 2003
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69
Az/NM/Ca/Nv/Tx
You can check with White's Metal Detectors.
Their deep seeker will detect caves, tunnels and such.
I believe the detector is a model 808 ?
Regradless, you can ask them which one will detect voids !
Resistivity devices and "mags" will not work!
Magnetometers are only used for finding ferrous metals!
Cptbil
 
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C

Charles, Oak Island, NC

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Keep a check on ebay for magnetometers
 
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Charles, Oak Island, NC

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what about ground penetrating sonar ??
 

cptbil

Bronze Member
Mar 27, 2003
1,402
69
Az/NM/Ca/Nv/Tx
Phil:
A "magnetometer " is just that!
It is a device to measure the earth's magnetic field!
When you pass over an item of ferrous metal it will unbalance the poles of the "mag"!
And! You get a signal!
But!
You are not looking for magnetic metal (ferrous) !
You are looking for a "void" in the ground!
I have since found out that the White's 808 detector will locate caverns and such!
A ground penetrating radar is great!
But! Who can afford the price of a good one!
Your best bet would be to try the White 808 !
 

rgecy

Bronze Member
Jun 14, 2004
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Beaufort, SC
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Phil,

For less than you could rent one for, you could build a magnetometer/gradiometer.? And yes they will find voids and caverns.? The disrupted or moved earth will give off different magnetic strengths and can be detected by magnetometers and gradiometers.? There is a kit sold by Fat Quaters Software in the US that has everything you need to build a great magnetometer.The key would be to chart the area and the readings you get from the mag.? There are several ways to do this.?

One: You can set up a grid at 10 ft spacing and walk the grid, taking measurements every 10 feet and charting the field strengths on a map of the area.? Once completed you would be able to see any patterns in the measurements that would explain any differences in the field strength.?

Two: You get a device that will log your measurements and record gps settings at the same time.? Then you could download this to a computer for graphical display.? There is a great article this month in Every Day Practical Electronics titled EPE PIC Magnetometry Logger.? It is a two part article that explains how to build a? Data Logger for the Speak FGM-3 Gradiometer.? I have built the Gradiomter and it is working great.? I have been field testing it to detect wrecks in up to 30 feet of water.? Here is a link to Carl Morelands site that explains how to buy the kit and assembly instructions for the basic gradiometer.? The data logger is on the EPE web site and I can't wait for next months article on the software and gps capabilities.

Good Luck,
Robert Gecy
 

yanis

Jr. Member
Aug 9, 2004
26
0
A magnetometer wil find your friends cave or underground opening,
A negative anomaly wil be indicated by the missing soil,

Regards
Yanis
 

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