Speaker 1: Get in touch with technology with tech Stuff from how
Speaker 1: stuff Works dot com. Hey there, and welcome to tech Stuff.
Speaker 1: I'm your host, Jonathan Strickland. I'm an executive producer with
Speaker 1: How Stuff Works in love all things tech and back
Speaker 1: on October two thousand eleven, my co host Chris Paulette
Speaker 1: and I sat down in a tiny little alcove at
Speaker 1: the then headquarters of How Stuff Works in Buckhead, Georgia, Buckhead, Atlanta.
Speaker 1: I'm kind of glad we're not in that particular alcove
Speaker 1: now I'm in a much nicer studio. But we sat
Speaker 1: down to talk about how metal detectors work. What is
Speaker 1: the operating principle behind metal detectors, what's the science behind it.
Speaker 1: So you're about to enjoy this classic episode of tech
Speaker 1: Stuff how metal detectors work, And I'll talk to you
Speaker 1: again in just a moment. So today we are going
Speaker 1: to talk about this. You know what, This was a
Speaker 1: topic that I don't know that anyone has ever requested. Um.
Speaker 1: It came to me actually as I was looking through
Speaker 1: stuff in my basement and went metal detectors. How should
Speaker 1: talking about We've never talked about metal detective Actually, we've
Speaker 1: sort of talked about metal detectors, because metal detectors use
Speaker 1: a lot of the technology we talked about before, especially
Speaker 1: the relationship of magnetism to electricity. Yeah, um, but yeah,
Speaker 1: I mean it's something that we run into very often,
Speaker 1: especially if we travel and walk through the metal detectors
Speaker 1: at the airport. If we're not getting back scattered or uh,
Speaker 1: you know, dropping stuff that you can't find, losing your
Speaker 1: wedding ring and the malts outside. Yikes, that's good stuff.
Speaker 1: I've done that. I still have it, so there you go.
Speaker 1: I've never lost my wedding ring. All right, Well it
Speaker 1: was only temporary. So anyway, metal detectors talk about what
Speaker 1: they are. We're mostly going to be talking about the
Speaker 1: kind that you would you would care you with you
Speaker 1: you know, the portable metal detectors that you would use
Speaker 1: when looking for say, loose change on the beach, or
Speaker 1: you know, searching for that rare civil war uh bullet
Speaker 1: or a gun that might be part of you know,
Speaker 1: in an area that you knew the battle happened here,
Speaker 1: so there may very well be stuff here. Yeah. We
Speaker 1: we should definitely talk about some of the applications of
Speaker 1: the technology. Um, and I would like to point out
Speaker 1: that we have an excellent article on how stuff works
Speaker 1: dot com if you're interested in learning more, um, how
Speaker 1: metal detectors work. Yeah, it should be pretty easy for
Speaker 1: people to find, written by Jeff Tyson, and it is
Speaker 1: a very good article and very uh simple to follow,
Speaker 1: easy to understand. I would say this is this is
Speaker 1: one of those really great how stuff works articles. Yeah.
Speaker 1: You know, by the time you get through it and
Speaker 1: you're like, oh, yeah, no, that totally makes sense, especially
Speaker 1: if you have a little bit of grounding in the
Speaker 1: way electromagnetism works and conductors and inducers. Right, So we'll
Speaker 1: we'll cover that. I mean, we've talked about an in
Speaker 1: previous podcast, but we'll we'll do a quick brush up
Speaker 1: so that we can explain it. Um, so you wanna,
Speaker 1: let's let's talk about the the Jeff does a great
Speaker 1: job at breaking down what the typical portable metal detector,
Speaker 1: the four main parts of one, what they would be. Yeah,
Speaker 1: I mean, if you've ever seen people walking around with
Speaker 1: a metal detector, you you sort of know what they
Speaker 1: look like. They have a round dish part that's used
Speaker 1: close to the ground, right, that's a that's called the
Speaker 1: coil um then yes, And then you have the stabilizer um,
Speaker 1: which is the part that you actually hold onto, that
Speaker 1: holds onto europe, that that you see on your arm
Speaker 1: because you know, frankly, having used a metal detector, it's
Speaker 1: not the lightest thing, right. This this helps, This helps
Speaker 1: distribute the weight somewhat so that you're not you don't
Speaker 1: feel like you're carrying around a you know, ten pound
Speaker 1: brick the whole time, because without that then you would
Speaker 1: get very tired very quickly. Yeah. And the the ten
Speaker 1: pound the aforementioned ten pound brick, which probably isn't ten pounds,
Speaker 1: but it certainly can feel that way after a while.
Speaker 1: That's the control box, uh, And you've got all your
Speaker 1: your electronics in there. And and then the the connecting bit, yes,
Speaker 1: the long skinny part that's the shaft. Yes, it connects
Speaker 1: the coil at the base to the part that you're holding,
Speaker 1: and the of course the control box. So those are
Speaker 1: your four basic parts of your basic metal detector. Yes.
Speaker 1: And then you know you have your headphones because this
Speaker 1: is one of our episodes of stuff that beeps and
Speaker 1: stuff what beats? Stuff? What beeps and it it does
Speaker 1: in fact deep Yeah, there's usually some sort of audible
Speaker 1: alert that you have in fact detected metal and now
Speaker 1: and more sophisticated UH, metal detectors will tell you a
Speaker 1: lot more often with uh, well sometimes with with an
Speaker 1: audible tone, but also with a visual uh, some kind
Speaker 1: of visual analysis. We can get into that to in
Speaker 1: a minute. So there are three main types of metal detectors,
Speaker 1: the ones at work, the three three main approaches to
Speaker 1: to metal detection. Let's say, Uh, there's UM, there's the
Speaker 1: very low frequency which is probably the most um, the
Speaker 1: most popular or the most common type of MEL detector,
Speaker 1: at least for the portable metal detectors. UM. Yeah. When
Speaker 1: we get into this, you'll you'll see that each of
Speaker 1: these different types has its own strengths and weaknesses. And
Speaker 1: you might say, well, the VLF detector sounds great, why
Speaker 1: would you use the others? We'll get into that. Yeah.
Speaker 1: The other two are pulse induction and beat frequency oscillation. Yeah.
Speaker 1: I I knew a beat frequency oscillator once. He was awesome. Anyway,
Speaker 1: I think there was something else I guess, So, yeah,
Speaker 1: that's the beat boxer frequency oscillator. That the uh, the
Speaker 1: VLF metal detector is the type that I have. UM,
Speaker 1: and uh the the basic differences, uh, and these is
Speaker 1: you know, you'll see those really in the coils. To
Speaker 1: be honest, because the VLF has two different coils. One
Speaker 1: transmits um and and the other is basically an antenna
Speaker 1: to pick up the signals, so they're shielded from one another,
Speaker 1: so it doesn't pick up because otherwise you turned it on,
Speaker 1: you would just have the receiver saying, oh my gosh,
Speaker 1: there's metal everywhere. Holy crap, you're rich, even up in
Speaker 1: the air. It's it's literally everywhere. Yeah, that would that
Speaker 1: would not be very useful. And taking this back to
Speaker 1: the store where I bought it. It's a detector detector.
Speaker 1: This does not do me any good. It's a detected
Speaker 1: or it's a detected or where's perry? So the the
Speaker 1: the transmitter coil um it's it think of a circle,
Speaker 1: all right. It's the circular part at the base of
Speaker 1: the male detector. And if you were to take it apart,
Speaker 1: which I do not recommend you do, you would see
Speaker 1: that there is a warrant point your warranty and it
Speaker 1: may not work anymore. You will have a there's a
Speaker 1: coil of wire that goes around the perimeter of this circle.
Speaker 1: Like it's it's wrapped around. So the circle itself is
Speaker 1: let's say it's like a quarter of an inch thick,
Speaker 1: and you've got this coil of wire that's that's coiled
Speaker 1: around this quarter of an inch all the way around
Speaker 1: the perimeter of this circle. When you run electricity through
Speaker 1: this coil of wire, what happens besides the fact that
Speaker 1: electrons are moving through because of the nature of electricity
Speaker 1: and magnetism, Well, when you run electricity around a coil
Speaker 1: like that, it generates a magnetic field. That's right, It
Speaker 1: does generate a magnetic field, and it generates a magnetic
Speaker 1: field perpendicular to the direction of the electricity. It's just
Speaker 1: the nature of electromagnetism. It's amazing, it's awesome. That's what
Speaker 1: how electro magnets work and UH dynamo's work in UH
Speaker 1: and sort of using this reverse um. So you've got
Speaker 1: electricity flowing through these coils, and that generates the magnetic field. Well,
Speaker 1: it doesn't just the electricity. Electricity doesn't just flow in
Speaker 1: one direction, no, it it goes back and forth. It
Speaker 1: alternates very very very fast, almost as fast as I
Speaker 1: waffle back and forth on what I want to eat
Speaker 1: for lunch. And that means that the magnetic field also alternates.
Speaker 1: The direction of the magnetic field changes. Uh And if
Speaker 1: you think of it in terms of the disc, the
Speaker 1: the coil disc being towards the ground, you can think
Speaker 1: of it as the magnetic field occasionally is pushing against
Speaker 1: or pulling the ground in general. That just think of
Speaker 1: it that way. That's the direction of the magnetic field
Speaker 1: while the electricity is going around and around in a circle,
Speaker 1: back and forth and in the various directions, and that
Speaker 1: alternation is happening hundreds of times per second. So you've
Speaker 1: got this magnetic field that's that's just oscillating essentially right
Speaker 1: there against the ground. When it comes to contact with
Speaker 1: something that is metal, well, the metal will start to
Speaker 1: that magnetic field will cause a a weaker magnetic field
Speaker 1: to generate around the metal object. Yeah. Basically induces a
Speaker 1: magnetic field in a metal object in the ground. So
Speaker 1: let's say, uh, um, you drop a screw and when
Speaker 1: you're trying to build something outside and you're trying to
Speaker 1: find it with your metal detector so that you don't
Speaker 1: step on it with a bare foot, and you know,
Speaker 1: need a trip to the hospital and a technis shot. Um.
Speaker 1: So as soon as you run the coil of the
Speaker 1: field and you're not trying to touch the ground with it,
Speaker 1: you really just need it close to the ground. Um,
Speaker 1: it will find the screw. The screw will basically start
Speaker 1: inducing a It will metal detect detector will generate a field,
Speaker 1: and that will cause the screw to generate its own
Speaker 1: a weaker magnetic Yeah, yeah, considerably weaker, but it will
Speaker 1: the metal detector, Uh, the antenna coil and the transmitter
Speaker 1: coil will say, oh, look there's something right there that
Speaker 1: is generating a magnetic field. It's right here. Chris and
Speaker 1: I have a lot more interesting things to say about
Speaker 1: metal detectors, but first let's take a quick break to
Speaker 1: thank our sponsor. So, if you have a coil of
Speaker 1: wire and you introduce it into a fluctuating magnetic field,
Speaker 1: that will induce the flow of electricity within the wire.
Speaker 1: Just as electricity and the wire will create generate a
Speaker 1: magnetic field, a magnetic field will induce electricity to run
Speaker 1: through wire fluctuating magnetic field. It can't just be just
Speaker 1: a magnetic field. So when the weak magnetic field from
Speaker 1: the mental object hits that that the wire in the
Speaker 1: the the the receiver coil that generates electricity which then
Speaker 1: alerts the control box and that that's what. Then when
Speaker 1: the control box gets an electric signal from the receiver coil,
Speaker 1: that says beep, something is here, stuff, what beeps? Yep? Stuff?
Speaker 1: What beeps? So yeah, that's the basic uh way that
Speaker 1: a VLF metal detector works. It shoots out this magnetic field.
Speaker 1: The polarization is alternating the same as the the flow
Speaker 1: of electricity around the the the transmitter coil, and then
Speaker 1: the receiver coil picks up any magnetic fields generated by
Speaker 1: metal objects that are under the surface of the ground.
Speaker 1: It's pretty cool and generally it will go more or
Speaker 1: less about a foot. Yeah, you're not gonna find you know,
Speaker 1: the Earth's core. Yea with a metal detect and the
Speaker 1: depth of what the depth of the The effectiveness of
Speaker 1: this metal detector is also going to be dependent on
Speaker 1: other factors, like the nature of the metal object itself,
Speaker 1: because some some metal objects are going to generate a
Speaker 1: stronger magnetic field than others, like iron. Uh. It will
Speaker 1: also depend on the composition of the soil. Yes, so
Speaker 1: the soil has a lot of elements in it that
Speaker 1: would create a magnetic field, you're gonna get a lot
Speaker 1: of interference, yeah, or or an environment where uh that
Speaker 1: that would conduct electricity more readily, Like if you were
Speaker 1: trying to look for something and say saltwater, you might
Speaker 1: have more difficulty than if you were looking, you know,
Speaker 1: on on a different type of soil. UM. Now there
Speaker 1: is something to uh called phase shifting, Yes, and that's
Speaker 1: how it's able to tell what sort of metal, what
Speaker 1: sort of metal it is, UM. And it really has
Speaker 1: to do with the the inductance and the resistance of
Speaker 1: the object that you're looking for. Now, the inductance is
Speaker 1: um the objects ability to conduct electricity UM. And if
Speaker 1: it's inductive, it will be able to to conduct electricity easily,
Speaker 1: but it's slow to react to changes in the electrical current. UM.
Speaker 1: If it's resistive, it doesn't conduct electricity is easily, but
Speaker 1: it is quick to react to those those changes. And
Speaker 1: a sophisticated metal detector will be able to tell you, well,
Speaker 1: that's I think that's gold or based upon that phase shift,
Speaker 1: because the face shift for a particular element is going
Speaker 1: to remain constant, you know. That's that's why if it
Speaker 1: didn't remain constant, then this wouldn't matter at all because
Speaker 1: it wouldn't you know, we wouldn't know, you know, It's
Speaker 1: like we just know something is down there, we wouldn't
Speaker 1: know have any way of guessing what it is. But
Speaker 1: because it's an inherent property of this particular material and
Speaker 1: it's really dependent upon the molecular composition of whatever that
Speaker 1: material is, UM, then we can make start making guesses
Speaker 1: based on that phase shift. UM. And it's yeah, the
Speaker 1: face shift, you know, with it being that difference in
Speaker 1: timing between the transmitters frequency uh and the frequency of
Speaker 1: the magnetic wave that's generated by the object. Um. You know,
Speaker 1: it's these are sort of ranges, right like if it
Speaker 1: if it's a certain range there, then the male detector
Speaker 1: can give a best guess as to what that material maybe.
Speaker 1: So there's never necessarily a guarantee that whatever it is
Speaker 1: you've detected is specifically going to be you know, aluminum
Speaker 1: versus goal or whatever. But it's a it's an indicator,
Speaker 1: so that uh, it gives you at least the idea
Speaker 1: of you know, is that you measure risk versus reward,
Speaker 1: the risk of exhausting yourself digging up useless junk versus
Speaker 1: the reward of possibly finding something that is of true value.
Speaker 1: So that's really the whole purpose of this anyway. It's
Speaker 1: just you know, to kind of tune in on that
Speaker 1: beep and make it more meaningful so that you know,
Speaker 1: you don't waste your time digging up uh little pull
Speaker 1: tabs from soda cans. Yeah. Now, yeah, if you have
Speaker 1: a higher inductance, it's going to create a larger phase shift,
Speaker 1: and lower inductance has a smaller phase shift. Now, Uh,
Speaker 1: metal detectors use a phase demodulator to read this, and uh,
Speaker 1: what that creates is discrimination. Yeah, yeah, I know it's terrible,
Speaker 1: but oh no, not that. Within metal detectors, it's okay, Yeah,
Speaker 1: because the thing is a good metal detector will allow
Speaker 1: you to filter out stuff that you don't want because
Speaker 1: the metal detector, if you said it at a certain
Speaker 1: setting and say, you know, I'm really looking for metals
Speaker 1: that fall within this range, yeah, perhaps gold. I've actually
Speaker 1: seen uh, metal detector booths and they'll have like this
Speaker 1: giant jar of class rings that people have lost, which
Speaker 1: is sort of a you know reminder that you know, hey,
Speaker 1: you you can find stuff if you just take your
Speaker 1: metal to of course, people look at you funny, but yeah,
Speaker 1: that way. That way. Let's say that you're out there
Speaker 1: looking for something specific. You can you know, meld detectors
Speaker 1: have settings where you can, uh you can tell the
Speaker 1: meld detector to ignore anything outside of a particular range
Speaker 1: of frequencies. So in other words, you're saying, you might say,
Speaker 1: I'm only interested in finding silver. Let's say, so what
Speaker 1: I'll do is I'll set my meld detector so that
Speaker 1: it'll it'll only uh activate, it will only alert me
Speaker 1: if something that generates a magnetic frequency similar to that
Speaker 1: of silver is encountered by the metal detector. So in
Speaker 1: other words, what you might you might pass over a
Speaker 1: gold deposit and nothing happens. But as soon as you
Speaker 1: go over that that silver half dollar but ink, and
Speaker 1: then you dig it up and you like, hey, look
Speaker 1: I'm rich. I Meanwhile, the gold guy behind you was like, sucker.
Speaker 1: Well that's that. That can be called notching. Basically, you
Speaker 1: set it for a if you imagine a scale, uh
Speaker 1: you know, he's one notch on that scale. Or some
Speaker 1: of the more sophisticated metal detectors will allow you to
Speaker 1: set more than one notch r So that way you
Speaker 1: could look for both silver on gold and you'd say,
Speaker 1: ha ha, Mr smarty gold pants. Um, now that's that's
Speaker 1: the VLF. The post induction metal detector a little bit different. Yeah,
Speaker 1: it uses only a single coil, or it can use
Speaker 1: multiple coils working at the same time. Yeah, but they're
Speaker 1: these are these are coils that haven't that don't have
Speaker 1: that shielding. It's not like you have a transmitter coil
Speaker 1: and then a receiver coil, and all of these coils
Speaker 1: are generating very quick bursts of electricity, which of course
Speaker 1: creates a very sharp magnetic wave. And uh so it's
Speaker 1: just a really quick spike and then what will happen
Speaker 1: is that magnetic wave if it encounters a metal object again,
Speaker 1: that metal object will have to will generate its own
Speaker 1: magnetic wave, and the metal detector will pick up on that.
Speaker 1: And it's all it's kind of like an echo, right,
Speaker 1: It's kind of like an echo, right, thank you. So
Speaker 1: if you think about it that way, it's it's like
Speaker 1: sending out a signal and waiting for something to bounce back. Yeah,
Speaker 1: but it's very fast. I mean the average is about
Speaker 1: a hundred pulses per second, which is yeah, fairly rapid,
Speaker 1: pretty quick, and then you're looking for the reflected pulse. Yes,
Speaker 1: which is what the the object that is under the
Speaker 1: ground or wherever. Uh, that's the the the pulse that
Speaker 1: it generates in response to the one that came from
Speaker 1: the MEL detector. Yeah. Now it uses a these these
Speaker 1: types of metal detectors use a sampling circuit basically trying
Speaker 1: to determine whether it's actually metal that you're finding or
Speaker 1: something else, some other type of magnetic field that is
Speaker 1: interfering with this signal. And it's basically judging that based
Speaker 1: on the amount of time it takes, uh too to reflect. Um. Yeah,
Speaker 1: that's another thing that we should point out is that
Speaker 1: MEL detectors can and encounter lots of different kinds of interference.
Speaker 1: Not just the composition of the soil. But let's say
Speaker 1: that you happen to cross over where in elector called
Speaker 1: cable has been buried. That could cause a problem. Your
Speaker 1: metal detector might think that, hey, look there's gold in
Speaker 1: them our hills, and truth, what you've hit is the
Speaker 1: power line, which you don't want to dig that up. No,
Speaker 1: it could result in everything from death, which is in
Speaker 1: the metal detection biz we call a bad thing, or
Speaker 1: it could result in or and or it could result
Speaker 1: in an entire region losing electricity. That's also a bad thing.
Speaker 1: That's that's a very good point. I mean, these these
Speaker 1: metal detectures are not only incredibly useful, they can be
Speaker 1: a lot of fun. A lot of hobbyists love them.
Speaker 1: But you do have to be very very careful. Um,
Speaker 1: and it's good to know your the territory. To quote
Speaker 1: a certain musical, but yeah, I mean, you need to
Speaker 1: know the territory. You gotta know where you're you're digging
Speaker 1: because you you really could get hurt. Hey, guys, it's
Speaker 1: Jonathan from the present day, butting in here. I was
Speaker 1: to want to talk to you for a second because
Speaker 1: my my, my AD detector is going off. Looks like
Speaker 1: we've got a sponsor read So we have an integrator
Speaker 1: on these on these pulse induction metal detectives, and that's
Speaker 1: reading the signals from the sampling circuit and converting them
Speaker 1: to d C. That's not current, yeah, not the district
Speaker 1: of Columbia. Yeah, not not a comic book publisher either.
Speaker 1: And that's feeding into the audio circuit and that is
Speaker 1: what beats. Yeah, that's the stuff what beats. The pulse indicator.
Speaker 1: The thing is, uh, these are very good at detecting metal,
Speaker 1: but they're not very good at discriminating between different types
Speaker 1: of metal. UM. So you're not going to get the
Speaker 1: level of precision that you would get with a VLF
Speaker 1: metal detector. But you know, they also you've got to
Speaker 1: remember that these different types of detectors, while some of
Speaker 1: them may work in conditions that others do not, there's
Speaker 1: there's also a price range here as well. Oh yes, yes, now, yeah,
Speaker 1: the beat frequency oscillator metal detectors can be uh fairly affordable. UM.
Speaker 1: They also used two coils, but one is in the
Speaker 1: search head and the other one is actually in the
Speaker 1: control box. UM. They're connected to an oscillator that as
Speaker 1: pulsing UM many many times per second, thousands of times
Speaker 1: per second UM. And and the and the frequency of
Speaker 1: the one that's inside the control box and the one
Speaker 1: that's inside the actual detector are slightly offset. They're not
Speaker 1: in sync or backstreet voice. Oh you got the other
Speaker 1: one I was gonna do so yeah, well, ironically enough
Speaker 1: to our our current part of the conversation. They create
Speaker 1: radio waves UM, and then the receiver in the control
Speaker 1: box UH picks that up and plays tones to you
Speaker 1: know when you're you're coming into range of metal, right,
Speaker 1: because what's happening is that when the metal encounters this
Speaker 1: uh this this this electromagnetic field that is going to
Speaker 1: alter that radio wave. And so what's really listening for
Speaker 1: our changes in the sound that you're hearing. The change
Speaker 1: in the sound indicates that you have encountered something that
Speaker 1: is generating this magnetic field. Because of the one you're generating,
Speaker 1: they know what they're going through. Um. So yeah, I
Speaker 1: mean detectors killed the radio star. But these these uh,
Speaker 1: like I said, these are a lot cheaper to manufacture.
Speaker 1: And therefore, if you are uh interested in getting your
Speaker 1: feet wet uh in the metal detector, the thing is
Speaker 1: a hobby, you might consider this, but they're they're far
Speaker 1: less accurate as in terms of being able to give
Speaker 1: you any kind of discrimination or any really any real control. Um,
Speaker 1: they actually use these are the types of metal detectors
Speaker 1: that you the handheld detectors that they use the airport. Um,
Speaker 1: you know if you walk through the scanner and and
Speaker 1: then yeah, that's the type they use in the one.
Speaker 1: Because they don't really need to know whether it's gold
Speaker 1: or iron. They just want to know what it is
Speaker 1: that you've got now once once, once something beeps, then
Speaker 1: they can say, all right, well let's see what that is.
Speaker 1: They don't, you know, necessarily need to know immediately. Yeah.
Speaker 1: And the metal detectors, the frames at the airport, they
Speaker 1: work on essentially the same principles we've talked about here.
Speaker 1: They're generating electromagnetic fields, which of course has brought up
Speaker 1: some concerns with people who may have uh devices like
Speaker 1: medical devices that could react to electromagnetic fields. That's why
Speaker 1: you'll occasionally hear about UH folks like that having to
Speaker 1: go through like a pat down security as opposed to
Speaker 1: a metal detector, just because of the concern that it
Speaker 1: could interfere with a medical device. Right right now, with
Speaker 1: with all of these um, what you're gonna find depends
Speaker 1: on the type of metal detector, the type of metal
Speaker 1: that you're looking for, about how big it is, the
Speaker 1: kind of makeup of the soil, um any kind of
Speaker 1: interference from other objects, and the halo, which is basically
Speaker 1: you know, if you have a piece of metal in
Speaker 1: the soil, it's going to read a little bit differently,
Speaker 1: it's going to it's going to register is larger than
Speaker 1: it actually is. Yeah, it's it's because those interesting things. Yeah,
Speaker 1: they I could see your halo. I was I was waiting.
Speaker 1: I was trying so hard not to go into that.
Speaker 1: We've done so many songs references in this podcast. It's crazy.
Speaker 1: This might be our like our most intense the funny
Speaker 1: thing references per minute other than the first one. None
Speaker 1: of them have been metal. That's true, that's true. So
Speaker 1: but yeah, no, that this is really the halo effect
Speaker 1: is really an interesting thing. It's just this the fact
Speaker 1: that certain kinds of metal objects, uh, can actually increase
Speaker 1: the conductivity of the soil that's around on them. And
Speaker 1: the longer that object, those particular objects have been in
Speaker 1: the ground, the greater that conductivity change can be. So
Speaker 1: then yeah, you might be like, hey, there's a there's
Speaker 1: a Sherman tank down there or something, and it just
Speaker 1: turns out that there's another object that's been down there
Speaker 1: and has affected the conductivity of the soil. But it's
Speaker 1: pretty phenomenal. If you have a Sherman tank buried in
Speaker 1: your backyard, please give me a call. I'm I'm interested
Speaker 1: to well not anymore. Yeah, I mean, well, you think
Speaker 1: about it, it it makes sense. If you have let's say,
Speaker 1: let's say the aforementioned screw and it's been there for
Speaker 1: a couple of years, it's let's say iron and it's
Speaker 1: beginning to rust, it's beginning to disintegrate, and you can
Speaker 1: change the conduct conductivity depending on the Again, it also
Speaker 1: depends rain, and you know, it really depends upon the
Speaker 1: composition of the soil itself as well. So, yeah, if
Speaker 1: there's a lot of iron content in the soil, that's
Speaker 1: gonna cause some issues when you're when you're doing mild section,
Speaker 1: you know, you're just you're gonna get a lot of
Speaker 1: interference and you just have to factor that in. Doesn't
Speaker 1: mean that the metal detector is going to be useless.
Speaker 1: It just means that you have to kind of adjust
Speaker 1: your expectations and listen for bigger changes in UH in
Speaker 1: the soil content UH and not and kind of kind
Speaker 1: of ignore the noise, separate the signal from the noise. Yeah,
Speaker 1: I would argue that it probably takes some personal discrimination too.
Speaker 1: You really need to get out there in practice if
Speaker 1: you're going to start using doing metal detecting as a hobby,
Speaker 1: UM and maybe even trying it with things that you
Speaker 1: would that you know what they are. You know, some coins,
Speaker 1: a ring, a screw driver, you know something that you hammer, hammers,
Speaker 1: you know, sherman tanks, Uh, stuff that you do just
Speaker 1: you know, tend to run across in your general area. Well,
Speaker 1: you know, you never know what you're gonna find when
Speaker 1: you're out in a field somewhere, and if you can
Speaker 1: identify what they are, you can get a sense of
Speaker 1: what different metals sound like. How get a feel for
Speaker 1: how your metal detector works, how sensitive it is, and
Speaker 1: how sensitive it is. Um, Yeah, it can be a
Speaker 1: lot of fun to uh you were talking about before,
Speaker 1: like going to uh battlefields course, I imagine probably all
Speaker 1: the major battlefields have been picked pretty clean at this point,
Speaker 1: you would think. But it's it's amazing what you can
Speaker 1: stumble across. It's again, it's one of those things where
Speaker 1: it may be it may require a phenomenal amount of luck,
Speaker 1: sure experience, there's no such thing as luck, but it
Speaker 1: may require a phenomenal a series of coincidences in order
Speaker 1: for you to stumble across the right section to find
Speaker 1: something significant. But really you never know. You just it's
Speaker 1: it's amazing to me how something that you would think, oh, well,
Speaker 1: this has got so much traffic. There's no way there's
Speaker 1: anything of significance can be found there. And yet like
Speaker 1: five years later you'll find that the find of the injury.
Speaker 1: How did that happen? Yeah, and you don't know what's
Speaker 1: around in places that you know might be a value.
Speaker 1: I mean again, people find I'm still searching for black beards, treasure,
Speaker 1: all kinds of stuff out in time. I go to
Speaker 1: the airlinas out in normal places. Maybe you should actually
Speaker 1: go to the everyday beach instead of Finland. That's probably
Speaker 1: part of the problem. Yeah, you know, Charleston is so nice.
Speaker 1: I just like to know, spend some time there enough. Yeah,
Speaker 1: people even use them for prospecting, you know, and uh
Speaker 1: and for coin shooting. Now, if you do want to
Speaker 1: use your mail detective for prospecting, there are some things
Speaker 1: you need to remember. First, you have to grow a
Speaker 1: bear of at least a foot in length that needs
Speaker 1: to be gray and grizzly. He's gonne punchy, ladies and gentlemen. Second,
Speaker 1: you need to be able to say things like consarn
Speaker 1: it with a straight face. And then third, the most
Speaker 1: important thing about being a prospector is you have to
Speaker 1: develop your crazy prospect or dance when you strike gold.
Speaker 1: Very important. Yeah, coin shooting is the practice of looking
Speaker 1: for coins after an outdoor event like a wedding or
Speaker 1: or like stock you go to you go to some
Speaker 1: big outdoor conference and you take a mail to actor
Speaker 1: and you start looking for change. The thing is that
Speaker 1: if you live in an area where this sort of
Speaker 1: stuff goes on in a regular basis, you could presumably
Speaker 1: pay off that mail detector after you know, a few
Speaker 1: visits to these these areas, once the concert is over
Speaker 1: or a game or whatever. Um, you know. And and
Speaker 1: because we're usually talking about change, you know, some some
Speaker 1: nickels or dimes or quarters or whatever. But whatever money
Speaker 1: you use, because you know, it's not all just United
Speaker 1: States folks. Well, if you find euros, you're rich, because
Speaker 1: I think a euro is equivalent to like seventeen dollars
Speaker 1: at this point. Um, that's a gross exaggeration, but the
Speaker 1: point being that, you know, yeah, you could conceivably pay
Speaker 1: off your mail detect there's costs after a few visits,
Speaker 1: you know. Um. But although a lot of people just
Speaker 1: enjoy the this as a hobby, like it's just it's
Speaker 1: a way to get outside. You're enjoying your joining time
Speaker 1: outdoors and you're finding stuff which just brings you a
Speaker 1: level of of of satisfaction, right at least that whole
Speaker 1: treasure hunting aspect. You know when I when we discover something,
Speaker 1: there's an element of satisfaction there that you can't put
Speaker 1: a monetary value on. Who Yeah, yeah, you're just like, hey,
Speaker 1: look I found some money woo, And yeah, there's there's
Speaker 1: an enjoyment level there that goes beyond oh and it's
Speaker 1: worth you know, seventy five cents um, although the five
Speaker 1: cents always nice to have seventy five cents more than
Speaker 1: you had, but when you showed up at the field.
Speaker 1: So yeah, I keep wondering, actually, why the value of
Speaker 1: the giant jar of class rings. You'd figure they'd cash
Speaker 1: that in, Yeah, I mean for more than just selling
Speaker 1: metal detectors. Maybe that's more lucrative than selling off some
Speaker 1: of those classroom you have, prying out all the little
Speaker 1: jewels and melting that stuff down and then just hey,
Speaker 1: you know you can yourself bar a gold. It's worth
Speaker 1: its weight in gold. All right, guys, hope you enjoyed
Speaker 1: that classic episode of tech Stuff How Metal detect there's
Speaker 1: work if you would like to contact the show. Maybe
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Speaker 1: questions or concerns, maybe you just want to say, hey, Jonathan,
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Speaker 1: Tor has been working hard on that website for a while,
Speaker 1: so I know she's very excited that you guys are
Speaker 1: gonna get a chance to interact on it. She's just
Speaker 1: given me a big smile. She's dancing. Look at her,
Speaker 1: go gosh, sorry, wow, she just did the floss. Now
Speaker 1: she's doing the hand give. It's amazing. Thanks Torry. Well, guys,
Speaker 1: that's all for me. I'll talk to you again really
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