Speaker 1: Get in touch with technology with tex stuff from Hey
Speaker 1: there everyone, and welcome to tech stuff. This is Jonathan
Speaker 1: Strickland with another classic episode. Don't worry, We're gonna have
Speaker 1: new ones really soon, but this one is a pretty
Speaker 1: cool one. It's one that I really enjoyed doing with
Speaker 1: Chris Paillette several years ago. It's all about metal detectives,
Speaker 1: how they were today we are going to talk about.
Speaker 1: You know what, this was a topic that I don't
Speaker 1: know that anyone has ever requested. Um. It came to
Speaker 1: me actually as I was looking through stuff in my
Speaker 1: basement and went metal detectors. We should talk about We've
Speaker 1: never talked about metal detective Actually, we've sort of talked
Speaker 1: about metal detectors because metal detectors use a lot of
Speaker 1: the technology we talked about before, especially the relationship of
Speaker 1: magnetism to atricity. Yeah. Um, but yeah, I mean it's
Speaker 1: something that we run into very often, especially if we
Speaker 1: travel and walk through the metal detectors at the airport
Speaker 1: if we're not getting back scattered or you know, dropping
Speaker 1: stuff that you can't find, losing your wedding ring and
Speaker 1: the maltch outside. Yikes, that's good stuff. I've done that
Speaker 1: I still have it, So there you go. I've never
Speaker 1: lost my wedding ring. Alright, well it was only temporary.
Speaker 1: So anyway, metal detectors talk about what they are. We're
Speaker 1: mostly going to be talking about the kind that you
Speaker 1: would you would carry with you, you know, the portable
Speaker 1: metal detectors that you would use when looking for say,
Speaker 1: loose change on the beach, or you know, searching for
Speaker 1: that rare civil war uh bullet or a gun that
Speaker 1: might be part of you know, in an area that
Speaker 1: you knew the battle happened here, so there may very
Speaker 1: well be stuff here. Yeah, we should definitely talk about
Speaker 1: some of the applications of the technology GUM. And I
Speaker 1: would like to point out that we have an excellent
Speaker 1: article on how stuff Works dot com if you're interested
Speaker 1: in learning more. Um it's called how Metal Detectors Work. Yeah.
Speaker 1: It should be pretty easy for people to find, written
Speaker 1: by Jeff Tyson, and it is a very good article
Speaker 1: and very uh simple to follow, easy to understand. I
Speaker 1: would say this is this is one of those really
Speaker 1: great how stuff works articles. By the time you get
Speaker 1: through it and you're like, oh, yeah, no, that totally
Speaker 1: makes sense, especially if you have a little bit of
Speaker 1: grounding in the way electromagnetism works and conductors and inducers.
Speaker 1: So we'll we'll cover that. I mean, we've talked about
Speaker 1: an in previous podcast, but we'll we'll do a quick
Speaker 1: brush up so that we can explain it. 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. That's a that's called the coil. Then, yes,
Speaker 1: and then you have the stabilizer um, which is the
Speaker 1: part that you actually hold onto, that holds onto your
Speaker 1: that that you see under your arm, because you know, frankly,
Speaker 1: having used a metal detector, it's not the lightest thing, right.
Speaker 1: This This helps, This helps distribute the weight somewhat so
Speaker 1: that you're not you don't feel like you're carrying around
Speaker 1: a you know, ten pound brick the whole time, because
Speaker 1: without that then you would get very tired very quickly. Yeah,
Speaker 1: And the the ten pound the aforementioned ten pound brick,
Speaker 1: which probably isn't ten pounds, but it certainly can feel
Speaker 1: that way after a while. That's the control box, uh,
Speaker 1: and you've got all your your electronics in there. And
Speaker 1: and then then yes, the long skinny part that's the shaft. Yes,
Speaker 1: it connects the coil at the base to the part
Speaker 1: that you're holding, and the of course the control box.
Speaker 1: So those are your four basic parts of your basic
Speaker 1: metal detector. Yes. And then you know you have your headphones,
Speaker 1: because this is one of our episodes of stuff that
Speaker 1: beeps and stuff what beat stuff? What beeps and it
Speaker 1: it does in fact beep. Yeah, there's usually some sort
Speaker 1: of audible alert that you have in fact detected metal. Yeah. Now,
Speaker 1: more sophisticated uh, metal detectors will tell you a lot
Speaker 1: more often with uh, well sometimes with with an audible tone,
Speaker 1: but also with a visual uh, some kind of visual analysis.
Speaker 1: We can get into that too in a minute. So
Speaker 1: there are three main types of metal detectors, the ones
Speaker 1: at work, the three three main approaches to to metal detection.
Speaker 1: Let's say, uh, there's, um, there's the very low frequency,
Speaker 1: which is probably the most the most popular or the
Speaker 1: most common type of mel detector, at least for the
Speaker 1: portable metal detectors. Um. Yeah, they When we get into this,
Speaker 1: you'll you'll see that each of these different types has
Speaker 1: its own strengths and weaknesses. And you might say, well,
Speaker 1: the VLF detector sounds great, why would you use the others?
Speaker 1: We'll get into that. Yeah. The other two are pulse
Speaker 1: induction and beat frequency oscillation. Yeah. I knew a beat
Speaker 1: frequency oscillator once. He was awesome. Yeah, Anyway, something else.
Speaker 1: I guess that's the beat boxer frequency oscillator. That the uh,
Speaker 1: the VLF metal detector is the type that I have,
Speaker 1: UM and Uh. The the basic differences uh, and these
Speaker 1: is you'll see those really in the coils, to be honest,
Speaker 1: because the VLF has two different coils. One transmits UM
Speaker 1: and and the other is basically an antenna to pick
Speaker 1: up the signals, so they're shielded from one another so
Speaker 1: 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 it's a detector detector. This does not
Speaker 1: do me any good. It's a detect it's a detected
Speaker 1: at or where's perry. So the the the transmitter coil
Speaker 1: um it's it. Think of a circle, all right, It's
Speaker 1: a this circular part at the base of the metal detector.
Speaker 1: And if you were to take it apart, which I
Speaker 1: do not recommend you do, you would see that there
Speaker 1: is a pointer warranty and it may not work anymore.
Speaker 1: You will have a there's a coil of wire that
Speaker 1: goes around the perimeter of this circle like it's it's
Speaker 1: wrapped around. So the circle itself is let's say it's
Speaker 1: like a quarter of an inch thick, and you've got
Speaker 1: this coil of wire that's that's coiled around this quarter
Speaker 1: of an inch all the way around the perimeter of
Speaker 1: this circle. When you run electricity through this coil of wire,
Speaker 1: what happens besides the fact that electrons are moving through
Speaker 1: because of the nature of electricity and magnetism, well, when
Speaker 1: you run electricity around a coil like that, it generates
Speaker 1: a magnetic field. That's right, it does generate a magnetic field,
Speaker 1: and it generates a magnetic field perpendicular to the direction
Speaker 1: of the electricity. It's just the nature of electromagnetism. It's amazing,
Speaker 1: it's awesome. That's what how electro magnets work and UH,
Speaker 1: dynamo's work in UH and sort of using this in reverse. UM.
Speaker 1: So you've got electricity flowing through these coils and that
Speaker 1: generates the magnetic field. Well, it doesn't just the electricity.
Speaker 1: Electricity doesn't just flow in one direction, no, it it
Speaker 1: goes back and forth. It alternates very very very fast,
Speaker 1: almost as fast as I waffle back and forth on
Speaker 1: what I want to eat for lunch. And that means
Speaker 1: that the magnetic field also alternates. The the direction of
Speaker 1: the magnetic field changes. UH. And if you think of
Speaker 1: it in terms of the disc, the coil disc being
Speaker 1: towards the ground, you can think of it as the
Speaker 1: magnetic field occasionally is pushing against or pulling the ground
Speaker 1: in general. That just think of it that way. That's
Speaker 1: the direction of the magnetic field, while the electricity is
Speaker 1: going around and around in a circle, back and forth
Speaker 1: in in the various directions, and that alternation is happening
Speaker 1: hundreds of times per second. So you've got this magnetic field.
Speaker 1: That's that's just oscillating essentially right there against the ground.
Speaker 1: When it comes to contact with something that is metal, well,
Speaker 1: the metal will start to that magnetic field will cause
Speaker 1: a a weaker magnetic field to generate around the metal object. Yeah,
Speaker 1: basically induces a magnetic field in a metal object in
Speaker 1: the ground. So let's say, uh, um, you drop a
Speaker 1: screw and when you're trying to build something outside and
Speaker 1: you're trying to find it with your metal detector so
Speaker 1: that you don't step on it with a bare foot
Speaker 1: and you know, need a trip to the hospital and
Speaker 1: a tetennis shot. Um. So as soon as you run
Speaker 1: the coil of the field and you're not trying to
Speaker 1: touch the ground with it, you really just need it
Speaker 1: close to the ground. Um, it will find the screw.
Speaker 1: The screw will basically start inducing a It will metal
Speaker 1: detected detector will generate a field, and that will cause
Speaker 1: the screw to generate its own a weaker magnetic Oh yeah, yeah,
Speaker 1: considerably weaker, but it will the metal detector. Uh, the
Speaker 1: antenna coil inside the transmitter coil will say, oh, look
Speaker 1: there's something right there that is generating a magnetic field.
Speaker 1: It's right here. And the way that the antenna works
Speaker 1: is the way I was talking about with a dynamo. So,
Speaker 1: if you have a coil of wire and you introduce
Speaker 1: it into a fluctuating magnetic field, that will induce the
Speaker 1: flow of electricity within the wire. Right, just as electricity
Speaker 1: and the wire will create generated a magnetic field, a
Speaker 1: magnetic field will induce electricity to run through wire fluctuating
Speaker 1: magnetic field. It can't just be just a magnetic field.
Speaker 1: So when the weak magnetic field from the metal object
Speaker 1: hits that that the wire in the the the receiver
Speaker 1: coil that generates the electricity, which then alerts the control
Speaker 1: box that that's what When the control box gets an
Speaker 1: electric signal from the receiver coil, that says beep, something
Speaker 1: is here, stuff? What beeps? Yep? Stuff? What beeps? So yeah,
Speaker 1: that's the basic uh way that a VLF metal detector works.
Speaker 1: It shoots out this magnetic field. The polarization is alternating
Speaker 1: the same as the flow of electricity around the the
Speaker 1: the transmitter coil, and then the receiver coil picks up
Speaker 1: any magnetic fields generated by metal objec that are under
Speaker 1: the surface of the ground. It's pretty cool and generally
Speaker 1: it will go more or less about a foot. Yeah,
Speaker 1: you're not going to find you know, the Earth's core
Speaker 1: with a metal detect and the depth of what the
Speaker 1: depth of the The effectiveness of this metal detector is
Speaker 1: also going to be dependent on other factors, like the
Speaker 1: nature of the metal object itself, because some some metal
Speaker 1: objects are going to generate a stronger magnetic field than others,
Speaker 1: like iron. Uh. It will also depend on the composition
Speaker 1: of the soil. Yes, So the soil has a lot
Speaker 1: of elements in it that would create a magnetic field,
Speaker 1: You're gonna get a lot of interference, yeah, or or
Speaker 1: an environment where uh that that would conduct electricity more readily.
Speaker 1: Like if you were trying to look for something and
Speaker 1: say saltwater, you might have more difficulty than if you
Speaker 1: were looking, you know, on on a different type of soil. Um. Now,
Speaker 1: there is something to uh called phase shifting, Yes, And
Speaker 1: that's how it's able to tell what sort of metal,
Speaker 1: what sort of metal it is, UM. And it really
Speaker 1: has to do with the the inductance and the resistance
Speaker 1: of the object that you're looking for. Now, the inductance
Speaker 1: is um the objects ability to conduct electricity UM and
Speaker 1: if it's inductive, it will be able to to conduct
Speaker 1: electricity easily, but it's slow to react to changes in
Speaker 1: the electrical current. UM. If it's resistive, it doesn't conduct
Speaker 1: electricity is easily, but it is quick to react to
Speaker 1: those those changes. And a sophisticated metal detector will be
Speaker 1: able to tell you, well, that's I think that's gold,
Speaker 1: or I think that's high based upon that phase shift.
Speaker 1: Because the phace scheft 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
Speaker 1: know it's these are sort of ranges, right like if
Speaker 1: it if it's a certain range there, then the male
Speaker 1: detector can give a best guess as to what that
Speaker 1: material maybe. So there's never necessarily a guarantee that whatever
Speaker 1: it is you've detected is specifically going to be you know,
Speaker 1: aluminum 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, right,
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. Yes,
Speaker 1: so that's really the whole purpose of this anyways, just
Speaker 1: you know, to kind of tune in on that beep
Speaker 1: and make it more meaningful so that you know, you
Speaker 1: don't waste your time digging up little poll tabs from
Speaker 1: soda cans. Yeah. Now, yeah, if you have a higher inductance,
Speaker 1: it's going to create a larger phase shift, and lower
Speaker 1: inductance has a smaller phase shift. Now, metal detectors use
Speaker 1: a phase demodulator to read this, and uh, what that
Speaker 1: creates is discrimination. Yeah, yeah, I know it's terrible, but
Speaker 1: oh no, not within metal detectors. It's okay, yeah, because
Speaker 1: the thing is, a good metal detector will allow you
Speaker 1: to filter out stuff that you don't want because the
Speaker 1: metal detector, if you said it at a certain setting
Speaker 1: and say, you know, I'm really looking for metals that
Speaker 1: fall within this range, yeah, perhaps gold. I've actually seen
Speaker 1: uh metal detector booths and they'll have like this giant
Speaker 1: jar of class rings that people have lost, which is
Speaker 1: sort of a you know, reminder that you know, hey,
Speaker 1: you you can find stuff if you just take your
Speaker 1: mel 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, some meld
Speaker 1: detectors have settings where you can 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
Speaker 1: say I'm only interested in finding silver. Let's say, So
Speaker 1: what I'll do is I'll set my meld detector so
Speaker 1: that it'll it'll only uh activate, it will only alert
Speaker 1: me if something that generates a magnetic frequency similar to
Speaker 1: that of silver is encountered by the metal detector. So,
Speaker 1: in other words, but you might you might pass over
Speaker 1: a gold deposit and nothing happens. But as soon as
Speaker 1: you go over that that silver half dollar. But and
Speaker 1: then you dig it up and you're 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, one notch on that scale, or some of
Speaker 1: the more sophisticated metal detectors will allow you to set
Speaker 1: more than one notch, right, So that way you could
Speaker 1: look for both silver and gold and you'd say, ha ha,
Speaker 1: Mr smarty gold pants. Um. Now that's that's the VLF.
Speaker 1: The post induction metal detectors 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 there
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 electric city, which of
Speaker 1: course creates a very sharp magnetic wave. And uh so
Speaker 1: it's just a really quick spike and then what will
Speaker 1: happen 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 metal detector. Yeah. Now it uses a these these
Speaker 1: types of metal detectors use a sampling circuit basically trying
Speaker 1: to deter 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 U two to reflect. Um. Yeah,
Speaker 1: that's another thing that we should point out is that
Speaker 1: metal detectors can 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 an electrical cable
Speaker 1: has been buried. That could cause a problem. Your male
Speaker 1: detector might think that, hey, look there's gold in them
Speaker 1: the 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 BIS 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. Honestly, I got
Speaker 1: Rock Island going through my head. Cash for the merchant
Speaker 1: dies a. Sorry, all right. 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 it the audio circuit, and that
Speaker 1: is what beats. Yeah, that's the stuff what beats. The
Speaker 1: 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 the 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 boys or oh you got the
Speaker 1: other one I was gonna do so yeah, well, ironically
Speaker 1: enough to our our current part of the conversation, they
Speaker 1: create radio waves, um, and then the receiver in the
Speaker 1: control box uh picks that up and plays tones to
Speaker 1: let you 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 uh,
Speaker 1: this this this electromagnetic field that is going to alter
Speaker 1: that radio wave. And so what's really listening for our
Speaker 1: changes in the sound that you're hearing. The change in
Speaker 1: the sound indicates that you have encountered something that is
Speaker 1: generating this magnetic field. Because of the one year 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 and the metal detector the thing is
Speaker 1: a hobby, you might consider this, but they're they're far
Speaker 1: less accurate in terms of being able to give you
Speaker 1: any kind of discrimination or any really any real control.
Speaker 1: UM they actually use. These are the types of metal
Speaker 1: detectors that you the handheld detectors that they use the airport.
Speaker 1: Um you know, if you walk through the scanner and
Speaker 1: and then yeah, that's the type they use in the
Speaker 1: one because they don't really need to know whether it's
Speaker 1: gold or iron. They just want to know what it
Speaker 1: is that you've got now once once, once something beeps,
Speaker 1: then they can say, all right, well let's see what
Speaker 1: that is. 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 occasion we hear about UH folks like that having
Speaker 1: to go through like a pat down security as opposed
Speaker 1: to a metal detector, just because of the concern that
Speaker 1: it could interfere with a medical device. Right right now,
Speaker 1: with with all of these UM, what you're gonna find
Speaker 1: depends on the type of metal detector, the type of
Speaker 1: metal that you're looking for, about how big it is,
Speaker 1: the kind of makeup of the soil, um any kind
Speaker 1: of 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 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: and this might be our like our most intense that
Speaker 1: the funny thing reference per minute other than the first one.
Speaker 1: None of them have been metal. That's true, that's so.
Speaker 1: But yeah, now that it 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 can actually increase the
Speaker 1: conductivity of the soil that's around them, and the longer
Speaker 1: that object, those particular objects have been in the ground,
Speaker 1: the greater that conductivity change can be. So then yeah,
Speaker 1: you might be like, hey, there's a there's a Sherman
Speaker 1: tank down there is something. It just turns out that
Speaker 1: there's another object that's been down there and has affected
Speaker 1: the conductivity of the soil. That's pretty phenomenal. If you
Speaker 1: have a Sherman tank buried in your backyard, please give
Speaker 1: me a call. I'm I'm interested. Well not anymore, yeah,
Speaker 1: I mean, well, you think about it. It makes sense
Speaker 1: if you have let's say, let's say the aforementioned screw
Speaker 1: and it's been there for a couple of years, let's
Speaker 1: say iron and it's beginning to rust, it's beginning to disintegrate,
Speaker 1: and you can change the conduct conductivity depending on the Again,
Speaker 1: it also depend the soil. It's rain and you know, yeah,
Speaker 1: it really depends upon the composition of the soil itself
Speaker 1: as well. So, yeah, if there's a lot of iron
Speaker 1: content in the soil, that's gonna cause some issues when
Speaker 1: you're when you're doing metal detection, you know, you're just
Speaker 1: you're gonna get a lot of interference and you just
Speaker 1: have to factor that in. Doesn't mean that the metal
Speaker 1: detector is going to be useless. It just means that
Speaker 1: you have to kind of adjust your expectations and listen
Speaker 1: for bigger changes in UH in the soil content and
Speaker 1: not and kind of kind of ignore the noise, separate
Speaker 1: the signal from the noise. Yeah, I would argue that
Speaker 1: it probably takes some personal discrimination too. You really need
Speaker 1: to get out there in practice if you're going to
Speaker 1: start using doing metal detecting as a hobby, um, and
Speaker 1: maybe even trying it with things that you what that
Speaker 1: you know what they are. You know, some coins, a ring,
Speaker 1: a screw driver, you know, something that hammer, you know,
Speaker 1: German tanks, the stuff that you do just you know,
Speaker 1: tend to run across in your general area. Well, you know,
Speaker 1: you never know what going to find when you're out
Speaker 1: in the field somewhere, and if you can identify what
Speaker 1: they are, you can get a sense of what different
Speaker 1: metals sound like. How get a feel for how your
Speaker 1: metal detector works, Yeah, how sensitive it is and how
Speaker 1: sensitive it is. Um. Yeah, it can be a lot
Speaker 1: of fun to UH as you were talking about before,
Speaker 1: like going to UH battlefields. Of course, I imagine probably
Speaker 1: all the major battlefields have been picked pretty clean at
Speaker 1: this point, you would think, But it's it's amazing once
Speaker 1: you can stumble across It's again, it's one of those
Speaker 1: things where it may be it may require a phenomenal
Speaker 1: amount of luck. Sure experience, there's no such thing as luck,
Speaker 1: but it may require a phenomenal a series of coincidences
Speaker 1: in order for you to stumble across the right section
Speaker 1: to find something significant. But really you never know. You
Speaker 1: just it's it's amazing to me. How something that you
Speaker 1: would think, oh, well, this has got so much traffic,
Speaker 1: there's no way there's anything of significance can be found there.
Speaker 1: And yet like five years later you'll find that the
Speaker 1: find of the injury. How did that happen? Yeah, and
Speaker 1: you don't know what's around in places that you know
Speaker 1: might be a value. I mean again, people find I'm
Speaker 1: still searching for black Beard's treasure, all kinds of stuff
Speaker 1: out any time I go to the Carolina's out in
Speaker 1: normal places. Maybe you should actually go to the everyday
Speaker 1: beach instead of in land. That's probably part of the problem. Yeah,
Speaker 1: you know, Charleston is so nice. I just like to
Speaker 1: spend some time there. And yeah, people even use them
Speaker 1: for prospecting, you know, and uh and for coin shooting. Now,
Speaker 1: if you do want to use your mail detective for prospecting,
Speaker 1: there are some things you need to remember first you
Speaker 1: have to grow a beer of at least a foot
Speaker 1: in length. That needs to be gray and grizzly. He's
Speaker 1: gone punchy, ladies and gentlemen. Second, you need to be
Speaker 1: able to say things like consarnate with a straight face.
Speaker 1: And then third, the most important thing about being a
Speaker 1: prospector is you have to develop your crazy prospect or
Speaker 1: dance when you start gold. Very important. Yeah. Coin shooting
Speaker 1: is the practice of looking for coins after an outdoor
Speaker 1: event like a wedding or or like woodstock you go
Speaker 1: to you go to some big outdoor conference and you
Speaker 1: take a male detector and you start looking for for change.
Speaker 1: The thing is that if you live in an area
Speaker 1: where this sort of stuff goes on in a regular basis,
Speaker 1: you could presumably pay off that mail detector after you know,
Speaker 1: a few visits to these these areas, once the concert
Speaker 1: is over or a game or whatever. Um you know.
Speaker 1: And and because we're usually talking about change, you know
Speaker 1: some some nickels or dimes or quarters or whatever whatever
Speaker 1: money you use. 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 detective's cost after a few visits, you know. Um,
Speaker 1: But although a lot of people just enjoy this as
Speaker 1: a hobby, like it's just it's a way to get outside.
Speaker 1: You're enjoying your drawing time outdoors and you're finding stuff
Speaker 1: which just brings you a level of of of satisfaction
Speaker 1: right A means that whole treasure hunting aspect, you know,
Speaker 1: when I when we discover something, there's an element of
Speaker 1: satisfaction there that you can't put a monetary value on.
Speaker 1: Who Yeah, yeah you're just like, hey look I found
Speaker 1: some money, woo, and yeah, there's there's an enjoyment level
Speaker 1: there that goes beyond oh and it's worth you know,
Speaker 1: seventy five cents um. Although the se cents it's always
Speaker 1: nice to have seventy five cents more than you had,
Speaker 1: but when you showed up at the field, So yeah,
Speaker 1: I keep wondering, actually, why the value of the giant
Speaker 1: jar of class rings. You'd figure they'd cash that in, Yeah,
Speaker 1: I mean for more than just selling metal detectors. Maybe
Speaker 1: that's more lucrative than selling off some of those classroom
Speaker 1: prying out all the little jewels and melting that stuff
Speaker 1: down and then just hey, you now can yourself bar
Speaker 1: a gold? It's worth its waiting gold. I hope you
Speaker 1: enjoyed that look back at tech stuff and remember, if
Speaker 1: you want to get in touch with us, you can
Speaker 1: send me an email. The address is tech stuff at
Speaker 1: how stuff works dot com, or drop me a line
Speaker 1: on Facebook, Twitter or Tumbler. The handle of all three
Speaker 1: is tech stuff H s W. And I'll talk to
Speaker 1: you again really soon. For more on this and thousands
Speaker 1: of other topics, is it how stuff works dot com