metal detector theory

[ZeleC]

hello
could any one give me links regarding how metal detectors theory
i dont have the mind going into math and physics formulas so an advanced link wouldnt be a problem
thx in advance

 

[spit]

how to fool a metal detector

Hi,

check out: **broken link removed**

Spit

 

[electronrancher]

fooling a metal detector

You setup a resonant circuit using your detection coil - LRC. Now when this coil is floating in midair near no metal it always resonantes to the same voltage - a simple peak detector gives you a nice DC. Move it near a chunk of metal and the resonance frequency is changed, your peak goes down. the amount of change or the amount of frequency shift tells you how much metal you are near.

for example iron is more magnetic than aluminum, so a small amount of iron will cause a big change, whereas a large amount of copper or aluminum would be needed to make the same change.

It's pretty simple theory, but the cleverness comes in how you implement it - add an integrator onto the peak detector's DC output to give you a good indication of how big a piece of metal you just passed over. An integrator only shows the CHANGE, not the original DC level.. And there's more tricks you can probably read about online..

 

[Fragrance]

metal detector bratsk city ru

Hi Friend,


Look at the attachment a constructional project with theory how metal detector works and how coils are made for it what is the best frequency to work it

regards
Fragrance

 

[mbyka]

fool metal detector

**broken link removed**

**broken link removed**


**broken link removed**

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**broken link removed**

 

[ZeleC]

www.metal detector coil.hit.bg

thx guys for ur help
to be more precise i dont want to build a metal detector for gold or coins ,my objective is to build one like those found in an airport that detects if a person is carring any kind of metal objects .
i know that it may be the same principle as a coin metal detector , so i need links for such thing.
thx

 

[electronrancher]

metal detecteur building how to make

it's the same. detecting non-metal objects such as newer land mines takes special detection techniques but the principles are the same.
detecting metal objects? - start with these resources.

 

[sick_man]

surgical steel and metal detectors

hi

to detect gun shaped objects you use a low level xray device
burst from xray leds clusters
and a simple Xray tv cameras {a ccd} take the lense off a normal camera
hey presto it will detect the whole spectrum {not now limited by the poleroid conformal coating on the lense or use a solvent to remove the coating} you can even watch top secret undetectable planes flying about from there invisible heat trail {so much for the americans stealth}}
anyway from the clusters of leds a burst of xrays is given out {this can also be targeted by digital zoom of the ccd and cluster instesity.

clusters can also be in 3d so can capture the whole bags and right round a crowd in a single scan of four points by interplirating the data}
{one cluster in each corner one wideangle cdd in each wall and celling floor in its center of the clusters zones is the origin point or the other way round even both together for greater dexterity of the system is used fully in most places
and a computer scans the outputs for tell tale images
refering suspects and cctv realtimes also to the staff
nothing to do with metal detectors

your all living well in the past

wake up..... and see the sunshine


what if the gun is plastic and your bullets make from a soda syphon gas pellet tank filled into a shell shaped block
6 shots of c02 {dry ice}

hehe

at the same time
forinstance in the uk

all airports use scanners for faces
can process 20 million faces per second
and looks straight thru a disguise {even surgery}


so will take less that 100 mins to check every face in the world
and 1 day to check the same face against every known species faces

metal objects on persons
this is too unreliable a method

i can imagine in an airport 20 armed guys jumping out on anyone who had a brocken leg at one point or a wired jaw

these use too similar a steel to give a reliable signiture

trace other wise hit men would just use surgical steel
to make the gun so render the metal locator useless

read a few spy books {good fun}

as for a guns specific density
etc this is also useless
you just file a bit off a standard gun and the signarture changes

or simply wrap it in copper or place it in a cigar box lined with lead

to even fool xray yes but older non interplative xray

newer ccd can see thru lead and give a clean picture in colour of course as you can see the whole spectrum not just black and white {cromotographic technique like hospital is very narrow band and tuned to bone density as its norm a gun appears white only mosttimes you can read it}
with ccd computer method
the gun is in 3 d and rotates on the screen using a mouse or optical glove hands

 

[Fragrance]

gulocoma surgery

hi

to detect gun shaped objects you use a low level xray device
burst from xray leds clusters
and a simple Xray tv cameras {a ccd} take the lense off a normal camera
hey presto it will detect the whole spectrum {not now limited by the poleroid conformal coating on the lense or use a solvent to remove the coating} you can even watch top secret undetectable planes flying about from there invisible heat trail {so much for the americans stealth}}
anyway from the clusters of leds a burst of xrays is given out {this can also be targeted by digital zoom of the ccd and cluster instesity.

clusters can also be in 3d so can capture the whole bags and right round a crowd in a single scan of four points by interplirating the data}
{one cluster in each corner one wideangle cdd in each wall and celling floor in its center of the clusters zones is the origin point or the other way round even both together for greater dexterity of the system is used fully in most places
and a computer scans the outputs for tell tale images
refering suspects and cctv realtimes also to the staff
nothing to do with metal detectors

your all living well in the past

wake up..... and see the sunshine


what if the gun is plastic and your bullets make from a soda syphon gas pellet tank filled into a shell shaped block
6 shots of c02 {dry ice}

hehe

at the same time
forinstance in the uk

all airports use scanners for faces
can process 20 million faces per second
and looks straight thru a disguise {even surgery}


so will take less that 100 mins to check every face in the world
and 1 day to check the same face against every known species faces

metal objects on persons
this is too unreliable a method

i can imagine in an airport 20 armed guys jumping out on anyone who had a brocken leg at one point or a wired jaw

these use too similar a steel to give a reliable signiture

trace other wise hit men would just use surgical steel
to make the gun so render the metal locator useless

read a few spy books {good fun}

as for a guns specific density
etc this is also useless
you just file a bit off a standard gun and the signarture changes

or simply wrap it in copper or place it in a cigar box lined with lead

to even fool xray yes but older non interplative xray

newer ccd can see thru lead and give a clean picture in colour of course as you can see the whole spectrum not just black and white {cromotographic technique like hospital is very narrow band and tuned to bone density as its norm a gun appears white only mosttimes you can read it}
with ccd computer method
the gun is in 3 d and rotates on the screen using a mouse or optical glove hands

master you are right these kinds of gun used in medical field called endo scope and have a very power full ccd which can see any thing inside the body used during surgical procedure like kidney opration doctor can see
the hole thing inside the body throw a minor hole with the help of these kind of ccd camera,

wide spectrum range camera can be found easly from electronics market
i used this kind of camear in past in amedcal equipments called field analyzer, used to scan the eye for gulocoma,

one thing more the gun metrial is special metrial so to detect a gun metrial the metal detector produce a special frequency lot of thinking
and way open but the right way is to used wide angle ccd

 

[AVIANO]

gold detector theory

Although this topic in the edaboard is old now (not the metal detection topic), but for the sake of discussion, what about the detecting of metal (a gun etc) from a person 50 meters away? Because I don't thing so that a coil can produce such a long field or it is practical.
Is there any theory or practical circuit?