1 00:00:00,280 --> 00:00:02,960 Speaker 1: Brought to you by the reinvented two thousand twelve Camray. 2 00:00:03,160 --> 00:00:08,920 Speaker 1: It's ready. Are you get in touch with technology with 3 00:00:09,000 --> 00:00:17,640 Speaker 1: tech Stuff from how stuff works dot com. Hello again, everyone, 4 00:00:17,720 --> 00:00:20,119 Speaker 1: Welcome to tech stuff. My name is Chris Polett and 5 00:00:20,120 --> 00:00:22,840 Speaker 1: I'm an editor at how stuff works dot com. I 6 00:00:22,880 --> 00:00:27,320 Speaker 1: worked with a person across from me pretty often. Uh. 7 00:00:27,360 --> 00:00:29,920 Speaker 1: He has a senior writer at how stuff works dot com. Also, 8 00:00:30,040 --> 00:00:34,280 Speaker 1: his name is Jonathan Strickland. New Wave tried to kill 9 00:00:34,320 --> 00:00:37,159 Speaker 1: the Metal but they failed as they were stricken down 10 00:00:37,240 --> 00:00:41,960 Speaker 1: to the ground. The second time I've quoted this band. Really, 11 00:00:42,479 --> 00:00:45,760 Speaker 1: at least it isn't from Tron, that's true. Not from Tron, 12 00:00:46,200 --> 00:00:50,680 Speaker 1: not from war games. Um. So today we are going 13 00:00:50,720 --> 00:00:53,280 Speaker 1: to talk about you know what, This was a topic, 14 00:00:53,720 --> 00:00:56,920 Speaker 1: uh that I don't know that anyone has ever requested. Um. 15 00:00:56,960 --> 00:01:00,680 Speaker 1: It came to me actually as I was looking through 16 00:01:00,800 --> 00:01:04,560 Speaker 1: stuff in my basement and went metal detectors you should 17 00:01:04,560 --> 00:01:07,479 Speaker 1: talk about We've never talked about metal detective Actually, we've 18 00:01:07,520 --> 00:01:10,480 Speaker 1: sort of talked about metal detectors because metal detectors use 19 00:01:10,520 --> 00:01:14,000 Speaker 1: a lot of the technology we talked about before, especially 20 00:01:14,319 --> 00:01:19,399 Speaker 1: the relationship of magnetism to electricity. Yeah, um, but yeah, 21 00:01:19,400 --> 00:01:22,600 Speaker 1: I mean it's something that we run into very often, 22 00:01:22,680 --> 00:01:25,280 Speaker 1: especially if we travel and walk through the metal detectors 23 00:01:25,280 --> 00:01:27,960 Speaker 1: at the airport. If we're not getting back scattered or 24 00:01:28,160 --> 00:01:31,120 Speaker 1: uh you know, dropping stuff that you can't find, losing 25 00:01:31,160 --> 00:01:36,000 Speaker 1: your wedding ring and the maltch outside. Yikes, that's good stuff. 26 00:01:36,040 --> 00:01:39,120 Speaker 1: I've done that. I still have it, so there you go. 27 00:01:39,280 --> 00:01:43,560 Speaker 1: I've never lost my wedding ring. Alright, Well it was 28 00:01:43,600 --> 00:01:47,840 Speaker 1: only temporary. So anyway, metal detectors talk about what they are. 29 00:01:48,160 --> 00:01:51,240 Speaker 1: We're mostly going to be talking about the kind that 30 00:01:51,280 --> 00:01:54,040 Speaker 1: you would you would carry with you, you know, the 31 00:01:54,320 --> 00:01:57,960 Speaker 1: portable metal detectors that you would use when looking for say, 32 00:01:58,000 --> 00:02:01,680 Speaker 1: loose change on the beach, or you know, searching for 33 00:02:01,760 --> 00:02:07,640 Speaker 1: that rare civil war uh bullet or a gun that 34 00:02:07,800 --> 00:02:09,920 Speaker 1: might be part of you know, in an area that 35 00:02:09,960 --> 00:02:12,520 Speaker 1: you knew the battle happened here, so there may very 36 00:02:12,520 --> 00:02:15,240 Speaker 1: well be stuff here. Yeah, we we should definitely talk 37 00:02:15,280 --> 00:02:18,160 Speaker 1: about some of the applications of the technology. UM and 38 00:02:18,200 --> 00:02:19,880 Speaker 1: I would like to point out that we have an 39 00:02:19,919 --> 00:02:22,160 Speaker 1: excellent article on how stuff works dot com if you're 40 00:02:22,160 --> 00:02:27,119 Speaker 1: interested in learning more. UM it's called how metal Detectors Work. Yeah, 41 00:02:27,120 --> 00:02:29,120 Speaker 1: it should be pretty easy for people to find, written 42 00:02:29,120 --> 00:02:32,760 Speaker 1: by Jeff Tyson, and it is a very good article 43 00:02:32,919 --> 00:02:37,400 Speaker 1: and very uh simple to follow, easy to understand. I 44 00:02:37,440 --> 00:02:39,840 Speaker 1: would say this is this is one of those really 45 00:02:40,000 --> 00:02:43,240 Speaker 1: great how stuff works articles. Yeah, by the time you 46 00:02:43,240 --> 00:02:45,400 Speaker 1: get through it and you're like, oh, yeah, no, that 47 00:02:45,480 --> 00:02:48,639 Speaker 1: totally makes sense, especially if you have a little bit 48 00:02:48,639 --> 00:02:54,920 Speaker 1: of grounding in the way electromagnetism works and conductors and inducers. 49 00:02:55,960 --> 00:02:58,840 Speaker 1: So we'll we'll cover that. I mean, we've talked about 50 00:02:58,840 --> 00:03:01,160 Speaker 1: an in previous podcast, but we'll will will do a 51 00:03:01,240 --> 00:03:03,960 Speaker 1: quick brush up so that we can explain it. Um, 52 00:03:04,000 --> 00:03:07,520 Speaker 1: so you wanna, let's let's talk about the the Jeff 53 00:03:07,560 --> 00:03:09,679 Speaker 1: does a great job at breaking down what the typical 54 00:03:10,680 --> 00:03:15,000 Speaker 1: portable metal detector, the four main parts of one, what 55 00:03:15,040 --> 00:03:17,520 Speaker 1: they would be. Yeah, I mean, if you've ever seen 56 00:03:17,520 --> 00:03:20,720 Speaker 1: people walking around with a metal detector, you you sort 57 00:03:20,720 --> 00:03:22,200 Speaker 1: of know what they look like. They have a round 58 00:03:22,280 --> 00:03:26,000 Speaker 1: dish part that's used close to the ground, right, that's uh, 59 00:03:26,200 --> 00:03:31,720 Speaker 1: that's called the coil. Yes, and then you have the stabilizer, um, 60 00:03:32,840 --> 00:03:35,200 Speaker 1: which is the part that you actually hold onto, that 61 00:03:35,400 --> 00:03:37,560 Speaker 1: holds onto your rope, that that you see on your 62 00:03:37,640 --> 00:03:40,640 Speaker 1: arm because you know, frankly having used a metal detector, 63 00:03:40,800 --> 00:03:43,720 Speaker 1: it's not the lightest thing, right, This this helps, This 64 00:03:43,760 --> 00:03:47,040 Speaker 1: helps distribute the weight somewhat so that you're not you 65 00:03:47,040 --> 00:03:49,800 Speaker 1: don't feel like you're carrying around a you know, ten 66 00:03:49,880 --> 00:03:53,800 Speaker 1: pound brick the whole time, because without that then you 67 00:03:53,800 --> 00:03:56,480 Speaker 1: would get very tired, very quickly. Yeah. And the the 68 00:03:56,560 --> 00:03:59,200 Speaker 1: ten pound the aforementioned ten pound brick, which probably isn't 69 00:03:59,240 --> 00:04:01,360 Speaker 1: ten pounds, but it's certainly can feel that way after 70 00:04:01,400 --> 00:04:04,400 Speaker 1: a while. That's the control box, uh, And you've got 71 00:04:04,440 --> 00:04:07,360 Speaker 1: all your your electronics in there. And and then the 72 00:04:09,200 --> 00:04:13,280 Speaker 1: connect yes, the long skinny part that's the shaft. Yes, 73 00:04:13,400 --> 00:04:16,159 Speaker 1: it connects the coil at the base to the part 74 00:04:16,200 --> 00:04:18,600 Speaker 1: that you're holding. And the of course the control box. 75 00:04:18,960 --> 00:04:21,600 Speaker 1: So those are your four basic parts of your basic 76 00:04:21,760 --> 00:04:24,680 Speaker 1: metal detector. Yes. And then you know you have your 77 00:04:24,680 --> 00:04:28,360 Speaker 1: headphones because this is one of our episodes of stuff 78 00:04:28,400 --> 00:04:31,440 Speaker 1: that beeps and stuff what beat? Stuff? What beeps? And 79 00:04:31,520 --> 00:04:34,480 Speaker 1: it it does in fact beep. Yeah, there's usually some 80 00:04:34,520 --> 00:04:40,279 Speaker 1: sort of audible alert that you have in fact detected metal. Yeah. Now, 81 00:04:40,440 --> 00:04:43,640 Speaker 1: more sophisticated uh, metal detectors will tell you a lot 82 00:04:43,680 --> 00:04:47,040 Speaker 1: more often with uh, well, sometimes with with an audible tone, 83 00:04:47,040 --> 00:04:50,880 Speaker 1: but also with a visual uh, some kind of visual analysis. 84 00:04:51,200 --> 00:04:53,440 Speaker 1: We can get into that too in a minute. So 85 00:04:53,880 --> 00:04:58,200 Speaker 1: there are three main types of metal detectors, the ones 86 00:04:58,240 --> 00:05:03,800 Speaker 1: that work, the three three main approaches to to metal detection. 87 00:05:03,960 --> 00:05:07,760 Speaker 1: Let's say, Uh, there's UM, there's the very low frequency, 88 00:05:07,839 --> 00:05:11,720 Speaker 1: which is probably the most um, the most popular or 89 00:05:11,760 --> 00:05:14,080 Speaker 1: the most common type of MEL detector, at least for 90 00:05:14,160 --> 00:05:18,360 Speaker 1: the portable metal detectors. UM. Yeah. When we get into this, 91 00:05:18,440 --> 00:05:20,720 Speaker 1: you'll you'll see that each of these different types has 92 00:05:20,800 --> 00:05:23,920 Speaker 1: its own strengths and weaknesses. And you might say, well, 93 00:05:23,960 --> 00:05:27,159 Speaker 1: the VLF detector sounds great, why would you use the others? 94 00:05:27,360 --> 00:05:30,960 Speaker 1: We'll get into that. The other two are pulse induction 95 00:05:31,920 --> 00:05:35,920 Speaker 1: and beat frequency oscillation. Yeah. I I knew a beat 96 00:05:35,960 --> 00:05:42,800 Speaker 1: frequency oscillator once. He was awesome. Yeah, Anyway, I think 97 00:05:43,120 --> 00:05:47,200 Speaker 1: something else, I guess. So that's the beat boxer frequency oscillator. 98 00:05:47,600 --> 00:05:51,200 Speaker 1: That the uh, the VLF metal detector is the type 99 00:05:51,200 --> 00:05:57,680 Speaker 1: that I have. UM and uh. The the basic differences 100 00:05:57,800 --> 00:06:01,680 Speaker 1: uh and these as you'll see those really in the coils, 101 00:06:02,120 --> 00:06:05,679 Speaker 1: to be honest, because the VLF has two different coils. 102 00:06:05,800 --> 00:06:11,000 Speaker 1: One transmits UM and and the other is basically an 103 00:06:11,000 --> 00:06:13,880 Speaker 1: antenna to pick up the signals, so they're shielded from 104 00:06:13,920 --> 00:06:16,840 Speaker 1: one another so it doesn't pick up because otherwise you 105 00:06:17,000 --> 00:06:18,960 Speaker 1: turn it on, you would just have the receiver saying, 106 00:06:19,040 --> 00:06:23,360 Speaker 1: oh my gosh, there's metal everywhere. Holy crap, you're rich, 107 00:06:24,040 --> 00:06:27,839 Speaker 1: even up in the air. It's it's literally everywhere. Yeah, 108 00:06:27,839 --> 00:06:30,040 Speaker 1: that would that would not be very useful. And taking 109 00:06:30,040 --> 00:06:32,400 Speaker 1: this back to the store where I bought it. It's 110 00:06:32,440 --> 00:06:35,080 Speaker 1: a detector detector. This does not do me any good. 111 00:06:35,240 --> 00:06:40,160 Speaker 1: It's a detector. It's a detected or where's perry? So 112 00:06:40,800 --> 00:06:47,159 Speaker 1: the the the transmitter coil um it's it. Think of 113 00:06:47,200 --> 00:06:51,320 Speaker 1: a circle, all right. It's a this circular part at 114 00:06:51,320 --> 00:06:54,360 Speaker 1: the base of the metal detector. And if you were 115 00:06:54,400 --> 00:06:56,720 Speaker 1: to take it apart, which I do not recommend you do, 116 00:06:57,320 --> 00:07:00,400 Speaker 1: you would see that there is a warrant point warranty 117 00:07:00,440 --> 00:07:02,599 Speaker 1: and it may not work anymore. You will have a 118 00:07:02,680 --> 00:07:06,359 Speaker 1: there's a coil of wire that goes around the perimeter 119 00:07:06,480 --> 00:07:08,960 Speaker 1: of this circle, like it's it's wrapped around. So the 120 00:07:09,000 --> 00:07:11,120 Speaker 1: circle itself is let's say it's like a quarter of 121 00:07:11,160 --> 00:07:13,280 Speaker 1: an inch thick, and you've got this coil of wire 122 00:07:13,360 --> 00:07:16,080 Speaker 1: that's that's coiled around this quarter of an inch all 123 00:07:16,120 --> 00:07:19,120 Speaker 1: the way around the perimeter of this circle. When you 124 00:07:19,200 --> 00:07:22,960 Speaker 1: run electricity through this coil of wire, what happens besides 125 00:07:23,000 --> 00:07:26,120 Speaker 1: the fact that electrons are moving through because of the 126 00:07:26,200 --> 00:07:32,120 Speaker 1: nature of electricity and magnetism, Well, when you run electricity 127 00:07:32,120 --> 00:07:35,160 Speaker 1: around a coil like that, it generates a magnetic field. 128 00:07:35,200 --> 00:07:38,400 Speaker 1: That's right. It does generate a magnetic field, and it 129 00:07:38,440 --> 00:07:42,440 Speaker 1: generates a magnetic field perpendicular to the direction of the electricity. 130 00:07:42,640 --> 00:07:46,160 Speaker 1: It's just the nature of electromagnetism. It's amazing, it's awesome. 131 00:07:46,240 --> 00:07:50,160 Speaker 1: That's what how electro magnets work. And uh dynamo's work 132 00:07:50,200 --> 00:07:53,800 Speaker 1: in uh and sort of using this in reverse. Um. 133 00:07:53,920 --> 00:07:57,440 Speaker 1: So you've got electricity flowing through these coils and that 134 00:07:57,520 --> 00:08:01,240 Speaker 1: generates the magnetic field. Well, it doesn't just the electricity. 135 00:08:01,280 --> 00:08:04,320 Speaker 1: Actricity doesn't just flow in one direction, no, it it 136 00:08:04,600 --> 00:08:08,040 Speaker 1: goes back and forth. It alternates very very very fast, 137 00:08:08,640 --> 00:08:10,760 Speaker 1: almost as fast as I waffle back and forth on 138 00:08:10,760 --> 00:08:13,160 Speaker 1: what I want to eat for lunch. And that means 139 00:08:13,240 --> 00:08:18,560 Speaker 1: that the magnetic field also alternates. The direction of the 140 00:08:18,600 --> 00:08:22,120 Speaker 1: magnetic field changes. Uh. And if you think of it 141 00:08:22,160 --> 00:08:26,880 Speaker 1: in terms of the disc, the coil disc being towards 142 00:08:26,920 --> 00:08:29,040 Speaker 1: the ground, you can think of it as the magnetic 143 00:08:29,080 --> 00:08:33,840 Speaker 1: field occasionally is pushing against or pulling the ground in general. 144 00:08:33,920 --> 00:08:35,679 Speaker 1: That just think of it that way. That's the direction 145 00:08:35,679 --> 00:08:37,880 Speaker 1: of the magnetic field while the electricity is going around 146 00:08:37,880 --> 00:08:40,080 Speaker 1: and around in a circle, back and forth and in 147 00:08:40,200 --> 00:08:45,320 Speaker 1: the various directions, and that alternation is happening hundreds of 148 00:08:45,320 --> 00:08:49,480 Speaker 1: times per second. So you've got this magnetic field that's 149 00:08:49,600 --> 00:08:54,000 Speaker 1: that's just oscillating essentially right there against the ground. When 150 00:08:54,000 --> 00:08:56,959 Speaker 1: it comes to contact with something that is metal, well, 151 00:08:57,000 --> 00:09:00,199 Speaker 1: the metal will start to that magnetic field will as 152 00:09:00,440 --> 00:09:05,320 Speaker 1: a a weaker magnetic field to generate around the metal object. Yeah. 153 00:09:05,400 --> 00:09:09,679 Speaker 1: Basically induces a magnetic field in a metal object in 154 00:09:09,720 --> 00:09:13,040 Speaker 1: the ground. So let's say, uh, um, you drop a 155 00:09:13,120 --> 00:09:17,920 Speaker 1: screw and when you're trying to build something outside and 156 00:09:17,960 --> 00:09:19,800 Speaker 1: you're trying to find it with your metal detector so 157 00:09:19,840 --> 00:09:21,439 Speaker 1: that you don't step on it with a bare foot 158 00:09:21,440 --> 00:09:23,600 Speaker 1: and you know need a trip to the hospital and 159 00:09:23,640 --> 00:09:27,280 Speaker 1: a technis shot. Um. So as soon as you run 160 00:09:27,440 --> 00:09:29,640 Speaker 1: the coil of the field and you're not trying to 161 00:09:29,640 --> 00:09:31,560 Speaker 1: touch the ground with it, you really just need it 162 00:09:31,760 --> 00:09:35,320 Speaker 1: close to the ground. Um, it will find the screw. 163 00:09:35,600 --> 00:09:39,200 Speaker 1: The screw will basically start inducing a it will end 164 00:09:39,960 --> 00:09:43,320 Speaker 1: metal detected detector will generate a field, and that will 165 00:09:43,480 --> 00:09:47,400 Speaker 1: cause the screw to generate its own a weaker magnetic 166 00:09:47,480 --> 00:09:51,160 Speaker 1: Oh yeah, yeah, considerably weaker, but it will the metal detector, Uh, 167 00:09:51,200 --> 00:09:55,000 Speaker 1: the antenna coil inside the transmitter coil will say, oh, 168 00:09:55,080 --> 00:09:58,120 Speaker 1: look there's something right there that is generating a magnetic field. 169 00:09:58,360 --> 00:10:00,959 Speaker 1: It's right here. And the way that the the that 170 00:10:01,520 --> 00:10:04,600 Speaker 1: antenna works is the way I was talking about with 171 00:10:04,640 --> 00:10:07,560 Speaker 1: a dynamo. So if you have a coil of wire 172 00:10:08,080 --> 00:10:11,440 Speaker 1: and you introduce it into a fluctuating magnetic field, that 173 00:10:11,480 --> 00:10:15,200 Speaker 1: will induce the flow of electricity within the wire. Just 174 00:10:15,400 --> 00:10:18,520 Speaker 1: as electricity and the wire will create generate a magnetic field, 175 00:10:18,800 --> 00:10:22,640 Speaker 1: a magnetic field will induce electricity to run through wire 176 00:10:23,440 --> 00:10:26,560 Speaker 1: fluctuating magnetic field. It can't just be just a magnetic field. 177 00:10:27,160 --> 00:10:31,960 Speaker 1: So when the weak magnetic field from the mental object 178 00:10:32,120 --> 00:10:36,559 Speaker 1: hits that that the wire in the the the the 179 00:10:36,600 --> 00:10:42,439 Speaker 1: receiver coil that generates the electricity, which then alerts the 180 00:10:42,440 --> 00:10:45,760 Speaker 1: control box that that's what When the control box gets 181 00:10:45,960 --> 00:10:50,160 Speaker 1: an electric signal from the receiver coil that says beep, 182 00:10:50,559 --> 00:10:55,800 Speaker 1: something is here stuff? What beeps? Yeah? Stuff what beeps. So, yeah, 183 00:10:55,960 --> 00:11:01,600 Speaker 1: that's the basic uh way that a VLF metal detector works. 184 00:11:01,640 --> 00:11:05,640 Speaker 1: It shoots out this magnetic field. The polar polarization is 185 00:11:05,640 --> 00:11:09,920 Speaker 1: alternating the same as the the flow of electricity around 186 00:11:10,000 --> 00:11:14,080 Speaker 1: the the the transmitter coil and then the receiver coil 187 00:11:14,120 --> 00:11:17,559 Speaker 1: picks up any magnetic fields generated by metal objects that 188 00:11:17,600 --> 00:11:20,720 Speaker 1: are under the surface of the ground. It's pretty cool 189 00:11:20,960 --> 00:11:25,320 Speaker 1: and generally it will go more or less about a foot. Yeah, 190 00:11:25,520 --> 00:11:28,080 Speaker 1: you're not going to find you know, the Earth's core 191 00:11:30,840 --> 00:11:34,720 Speaker 1: and the depth of what the depth of the The 192 00:11:34,760 --> 00:11:37,360 Speaker 1: effectiveness of this metal detector is also going to be 193 00:11:37,440 --> 00:11:41,400 Speaker 1: dependent on other factors, like the nature of the metal 194 00:11:41,440 --> 00:11:44,800 Speaker 1: object itself, because some some metal objects are going to 195 00:11:44,840 --> 00:11:49,240 Speaker 1: generate a stronger magnetic field than others, like iron. Uh. 196 00:11:49,240 --> 00:11:52,760 Speaker 1: It will also depend on the composition of the soil. 197 00:11:53,400 --> 00:11:56,080 Speaker 1: So the soil has a lot of elements in it 198 00:11:56,240 --> 00:11:59,000 Speaker 1: that would create a magnetic field, you're gonna get a 199 00:11:59,040 --> 00:12:03,959 Speaker 1: lot of interference, yeah, or or an environment where uh 200 00:12:04,000 --> 00:12:07,800 Speaker 1: that that would conduct electricity more readily. Like if you're 201 00:12:07,840 --> 00:12:11,600 Speaker 1: trying to look for something and say saltwater, you might 202 00:12:11,679 --> 00:12:14,200 Speaker 1: have more difficulty than if you were looking you know, 203 00:12:14,360 --> 00:12:18,200 Speaker 1: on on a different type of soil. UM. Now there 204 00:12:18,240 --> 00:12:22,480 Speaker 1: is something to uh called phase shifting, and that's how 205 00:12:22,480 --> 00:12:25,400 Speaker 1: it's able to tell what sort of metal, what sort 206 00:12:25,400 --> 00:12:28,560 Speaker 1: of metal it is UM, And it really has to 207 00:12:28,600 --> 00:12:32,160 Speaker 1: do with the the inductance and the resistance of the 208 00:12:32,160 --> 00:12:35,479 Speaker 1: object that you're looking for. Now, the inductance is UM 209 00:12:35,559 --> 00:12:40,559 Speaker 1: the objects ability to conduct electricity UM. And if it's inductive, 210 00:12:40,679 --> 00:12:43,440 Speaker 1: it would be able to to conduct electricity easily, but 211 00:12:43,600 --> 00:12:49,160 Speaker 1: it's slow to react to changes in the electrical current. UM. 212 00:12:49,200 --> 00:12:52,040 Speaker 1: If it's resistive, it doesn't conduct electricity is easily, but 213 00:12:52,120 --> 00:12:54,959 Speaker 1: it is quick to react to those those changes. And 214 00:12:55,200 --> 00:12:58,760 Speaker 1: a sophisticated metal detector will be able to tell you, well, 215 00:12:58,800 --> 00:13:03,560 Speaker 1: that's I think that's gold or based upon that phase shift. 216 00:13:03,600 --> 00:13:06,000 Speaker 1: Because the face shift for a particular element is going 217 00:13:06,040 --> 00:13:09,720 Speaker 1: to remain constant, you know. That's that's why if it 218 00:13:09,760 --> 00:13:12,640 Speaker 1: didn't remain constant, then this wouldn't matter at all, because 219 00:13:12,679 --> 00:13:14,880 Speaker 1: it wouldn't you know, we wouldn't know, you know, it's 220 00:13:14,880 --> 00:13:17,000 Speaker 1: like we just know something is down there, we wouldn't 221 00:13:17,040 --> 00:13:19,680 Speaker 1: know have any way of guessing what it is. But 222 00:13:19,840 --> 00:13:24,680 Speaker 1: because it's an inherent property of this particular material, and 223 00:13:24,679 --> 00:13:27,800 Speaker 1: it's really dependent upon the molecular composition of whatever that 224 00:13:27,840 --> 00:13:31,760 Speaker 1: material is. UM, then we can make start making guesses 225 00:13:31,840 --> 00:13:35,120 Speaker 1: based on that phase shift UM. And it's yeah, the 226 00:13:35,120 --> 00:13:37,080 Speaker 1: face shift, you know, with it being that difference in 227 00:13:37,120 --> 00:13:41,839 Speaker 1: timing between the transmitters frequency uh and the frequency of 228 00:13:41,880 --> 00:13:46,520 Speaker 1: the magnetic wave that's generated by the object. Um. You know. 229 00:13:46,640 --> 00:13:51,120 Speaker 1: It's these are sort of ranges, right like if it 230 00:13:51,480 --> 00:13:54,120 Speaker 1: if it's a certain range there, then the male detector 231 00:13:54,160 --> 00:13:57,680 Speaker 1: can give a best guess as to what that material maybe. 232 00:13:58,240 --> 00:14:02,720 Speaker 1: So there's no ever necessarily a guarantee that whatever it 233 00:14:02,760 --> 00:14:06,280 Speaker 1: is you've detected is specifically going to be you know, 234 00:14:06,320 --> 00:14:09,880 Speaker 1: aluminum versus goal or whatever. But it's a it's an indicator, 235 00:14:09,960 --> 00:14:13,360 Speaker 1: so that uh, it gives you at least the idea 236 00:14:13,400 --> 00:14:16,280 Speaker 1: of you know, is that you measure risk versus reward, right, 237 00:14:17,120 --> 00:14:21,400 Speaker 1: the risk of exhausting yourself digging up useless junk versus 238 00:14:21,440 --> 00:14:25,760 Speaker 1: the reward of possibly finding something that is of true value. Yes, 239 00:14:26,120 --> 00:14:29,000 Speaker 1: so that's really the whole purpose of this anyway. It's 240 00:14:29,040 --> 00:14:31,480 Speaker 1: just you know, to kind of tune in on that 241 00:14:31,560 --> 00:14:34,240 Speaker 1: beep and make it more meaningful so that you know, 242 00:14:34,280 --> 00:14:38,320 Speaker 1: you don't waste your time digging up uh little poll 243 00:14:38,400 --> 00:14:43,520 Speaker 1: tabs from soda cans. Yeah. Now, yeah, if you have 244 00:14:43,560 --> 00:14:47,320 Speaker 1: a higher inductance, it's going to create a larger phase shift, 245 00:14:47,360 --> 00:14:51,320 Speaker 1: and lower inductance has a smaller phase shift. Now, metal 246 00:14:51,360 --> 00:14:57,560 Speaker 1: detectors use a phase demodulator to read this, and uh, 247 00:14:57,720 --> 00:15:02,880 Speaker 1: what that creates is scrimination. Yeah, yeah, I know it's terrible, 248 00:15:03,000 --> 00:15:07,440 Speaker 1: but within metal detectors, it's okay, yeah, because the thing is, 249 00:15:08,080 --> 00:15:11,640 Speaker 1: a good metal detector will allow you to filter out 250 00:15:11,960 --> 00:15:15,720 Speaker 1: stuff that you don't want because the metal detector, if 251 00:15:15,720 --> 00:15:17,920 Speaker 1: you said it at a certain setting and say, you know, 252 00:15:17,960 --> 00:15:21,880 Speaker 1: I'm really looking for metals that fall within this range, yeah, 253 00:15:21,920 --> 00:15:27,080 Speaker 1: perhaps gold. I've actually seen uh, metal detector booths and 254 00:15:27,120 --> 00:15:29,920 Speaker 1: they'll have like this giant jar of class rings that 255 00:15:30,000 --> 00:15:32,880 Speaker 1: people have lost, which is sort of a you know, 256 00:15:32,960 --> 00:15:35,760 Speaker 1: reminder that you know, hey, you you can find stuff 257 00:15:35,800 --> 00:15:37,800 Speaker 1: if you just take your metal. Of course people look 258 00:15:37,800 --> 00:15:41,360 Speaker 1: at you funny, but yeah, that way. That way. Let's 259 00:15:41,360 --> 00:15:44,040 Speaker 1: say that you're out there looking for something specific, you 260 00:15:44,080 --> 00:15:47,480 Speaker 1: can you know, some meld detectors have settings where you can, uh, 261 00:15:47,640 --> 00:15:50,920 Speaker 1: you can tell the meld detector to ignore anything outside 262 00:15:51,000 --> 00:15:53,800 Speaker 1: of a particular range of frequencies. So in other words, 263 00:15:53,840 --> 00:15:57,400 Speaker 1: you're saying. You might say, I'm only interested in finding silver. 264 00:15:57,760 --> 00:16:00,000 Speaker 1: Let's say, So what I'll do is I'll set my 265 00:16:00,040 --> 00:16:04,200 Speaker 1: MELD detector so that it'll it'll only uh activate, it 266 00:16:04,200 --> 00:16:09,320 Speaker 1: will only alert me if something that generates a magnetic 267 00:16:09,800 --> 00:16:13,280 Speaker 1: frequency similar to that of silver is encountered by the 268 00:16:13,320 --> 00:16:15,560 Speaker 1: metal detector. So in other words, what you might you 269 00:16:15,640 --> 00:16:19,120 Speaker 1: might pass over a gold deposit and nothing happens. But 270 00:16:19,320 --> 00:16:21,720 Speaker 1: as soon as you go over that that silver half 271 00:16:21,720 --> 00:16:24,080 Speaker 1: dollar but ink, and then you dig it up and 272 00:16:24,120 --> 00:16:26,280 Speaker 1: you're like, hey, look I'm rich. I Meanwhile, the gold 273 00:16:26,280 --> 00:16:30,640 Speaker 1: guy behind you was like, sucker. Well that's that. That 274 00:16:30,680 --> 00:16:33,120 Speaker 1: can be called notching. Basically, you set it for a 275 00:16:33,840 --> 00:16:36,920 Speaker 1: if you imagine a scale, uh you know, one notch 276 00:16:36,960 --> 00:16:40,040 Speaker 1: on that scale, or some of the more sophisticated metal 277 00:16:40,080 --> 00:16:43,120 Speaker 1: detectors will allow you to set more than one notch r. 278 00:16:43,240 --> 00:16:44,880 Speaker 1: So that way you could look for both silver and 279 00:16:45,000 --> 00:16:50,320 Speaker 1: gold and you'd say, ha ha, Mr smarty gold pants. Um. 280 00:16:50,360 --> 00:16:55,080 Speaker 1: Now that's that's the VLF. The post induction metal detector 281 00:16:55,440 --> 00:16:57,280 Speaker 1: is a little bit different. Yeah, it uses only a 282 00:16:57,320 --> 00:17:01,000 Speaker 1: single coil, or it can use multiple oils working at 283 00:17:01,040 --> 00:17:03,320 Speaker 1: the same time. Yeah, but there these are these are 284 00:17:03,400 --> 00:17:06,359 Speaker 1: coils that haven't that don't have that shielding. It's not 285 00:17:06,440 --> 00:17:09,639 Speaker 1: like you have a transmitter coil and then a receiver coil, 286 00:17:10,840 --> 00:17:16,480 Speaker 1: and all of these coils are generating very quick bursts 287 00:17:16,560 --> 00:17:20,560 Speaker 1: of electricity, which of course creates a very sharp magnetic wave. 288 00:17:21,800 --> 00:17:24,240 Speaker 1: And uh so it's just a really quick spike. And 289 00:17:24,280 --> 00:17:26,720 Speaker 1: then what will happen is that magnetic wave if it 290 00:17:26,800 --> 00:17:29,399 Speaker 1: encounters a metal object. Again, that metal object will have 291 00:17:29,440 --> 00:17:33,760 Speaker 1: to will generate its own magnetic wave, and the metal 292 00:17:33,800 --> 00:17:36,160 Speaker 1: detector will pick up on that, and it's all it's 293 00:17:36,240 --> 00:17:38,760 Speaker 1: kind of like an echo, right, It's kind of like 294 00:17:38,800 --> 00:17:42,720 Speaker 1: an echo, right, thank you. So if you think about 295 00:17:42,720 --> 00:17:46,159 Speaker 1: it that way, it's it's like sending out a signal 296 00:17:46,200 --> 00:17:48,640 Speaker 1: and waiting for something to bounce back. Yeah, but it's 297 00:17:48,760 --> 00:17:51,040 Speaker 1: very fast. I mean the average is about a hundred 298 00:17:51,040 --> 00:17:55,440 Speaker 1: pulses per second, which is yeah, fairly rapid, pretty quick. 299 00:17:55,720 --> 00:17:59,240 Speaker 1: And then you're looking for the reflected pulse, yes, which 300 00:17:59,280 --> 00:18:02,679 Speaker 1: is what the the object that is under the ground 301 00:18:02,800 --> 00:18:07,639 Speaker 1: or wherever. Uh, that's the the the pulse that it 302 00:18:07,800 --> 00:18:10,480 Speaker 1: generates in response to the one that came from the 303 00:18:10,520 --> 00:18:14,040 Speaker 1: mel detector. Yeah, Now it uses a these these types 304 00:18:14,040 --> 00:18:16,960 Speaker 1: of metal detectors use a sampling circuit, basically trying to 305 00:18:17,000 --> 00:18:21,359 Speaker 1: determine whether it's actually metal that you're finding or something else, 306 00:18:21,440 --> 00:18:23,879 Speaker 1: some other type of magnetic field that is interfering with 307 00:18:23,920 --> 00:18:26,639 Speaker 1: this signal, and it's basically judging that based on the 308 00:18:26,680 --> 00:18:32,960 Speaker 1: amount of time it takes UH two to reflect. Um. Yeah, 309 00:18:33,000 --> 00:18:34,840 Speaker 1: that's another thing that we should point out is that 310 00:18:34,880 --> 00:18:38,520 Speaker 1: MEL detectors can and encounter lots of different kinds of interference. 311 00:18:39,320 --> 00:18:41,720 Speaker 1: Not just the composition of the soil. But let's say 312 00:18:41,760 --> 00:18:45,439 Speaker 1: that you happen to cross over where an electrical cable 313 00:18:45,520 --> 00:18:49,480 Speaker 1: has been buried. That could cause a problem. Your male 314 00:18:49,520 --> 00:18:52,240 Speaker 1: detector might think that, hey, look there's gold in them 315 00:18:52,240 --> 00:18:55,959 Speaker 1: the Oar hills, and truth, what you've hit is the 316 00:18:56,000 --> 00:18:58,560 Speaker 1: power line, which you don't want to dig that up. No, 317 00:18:58,960 --> 00:19:03,480 Speaker 1: it could result in everything from death, which UH is 318 00:19:03,520 --> 00:19:06,440 Speaker 1: in the metal detection biz we call a bad thing, 319 00:19:07,720 --> 00:19:11,480 Speaker 1: or it could result in or and or it could 320 00:19:11,520 --> 00:19:16,960 Speaker 1: result in an entire region losing electricity. That's also a 321 00:19:17,000 --> 00:19:20,240 Speaker 1: bad thing. That's that's a very good point. I mean, 322 00:19:20,280 --> 00:19:23,280 Speaker 1: these these metal detectures are not only incredibly useful, they 323 00:19:23,280 --> 00:19:24,920 Speaker 1: can be a lot of fun. A lot of hobbyists 324 00:19:25,040 --> 00:19:29,400 Speaker 1: love them, but you do have to be very very careful. Um. 325 00:19:29,520 --> 00:19:32,359 Speaker 1: And it's good to know your the territory to quote 326 00:19:32,400 --> 00:19:35,240 Speaker 1: a certain musical, but yeah, I mean you need to 327 00:19:35,280 --> 00:19:38,520 Speaker 1: know the territory. You gotta know where you're you're digging 328 00:19:39,000 --> 00:19:42,199 Speaker 1: because you you really could get hurt. Honestly, I've got 329 00:19:42,280 --> 00:19:46,119 Speaker 1: Rock Island going through my head. Now, cash for the merchandise, 330 00:19:47,240 --> 00:19:51,240 Speaker 1: al right, sorry, all right. So we have an integrator 331 00:19:52,000 --> 00:19:56,080 Speaker 1: on these, on these pulse induction metal detectives, uh, and 332 00:19:56,119 --> 00:19:59,360 Speaker 1: that's reading the signals from the sampling circuit and converting 333 00:19:59,359 --> 00:20:03,600 Speaker 1: them to D that's current Yeah, not the district of Columbia. Yeah, 334 00:20:03,680 --> 00:20:07,240 Speaker 1: not not a comic book publisher either. And that's feeding 335 00:20:07,240 --> 00:20:10,160 Speaker 1: into it the audio circuit and that is what beats. Yeah, 336 00:20:10,200 --> 00:20:12,879 Speaker 1: that's the stuff what beats for the pulse indicator. The 337 00:20:13,200 --> 00:20:16,440 Speaker 1: thing is, uh, these are very good at detecting metal, 338 00:20:16,520 --> 00:20:19,240 Speaker 1: but they're not very good at discriminating between different types 339 00:20:19,280 --> 00:20:23,000 Speaker 1: of metal. Um, So you're not going to get the 340 00:20:23,600 --> 00:20:26,440 Speaker 1: level of precision that you would get with a VLF 341 00:20:27,160 --> 00:20:30,639 Speaker 1: metal detector. But you know they also you've got to 342 00:20:30,680 --> 00:20:33,359 Speaker 1: remember that these different types of detectors, while some of 343 00:20:33,359 --> 00:20:36,160 Speaker 1: them may work in conditions that others do not. There's 344 00:20:36,240 --> 00:20:40,840 Speaker 1: there's also a price range here as well. Oh yes, yes, now, yeah, 345 00:20:40,880 --> 00:20:46,360 Speaker 1: the beat frequency oscillator metal detectors can be uh fairly affordable. Um. 346 00:20:46,400 --> 00:20:49,000 Speaker 1: They also used two coils, but one is in the 347 00:20:49,040 --> 00:20:51,080 Speaker 1: search head and the other one is actually in the 348 00:20:51,080 --> 00:20:54,800 Speaker 1: control box. UM. They're connected to an oscillator that as 349 00:20:55,760 --> 00:20:59,920 Speaker 1: pulsing UM many many times per second. That was in 350 00:21:00,040 --> 00:21:03,199 Speaker 1: of times per second UM. And and the and the 351 00:21:03,240 --> 00:21:06,240 Speaker 1: frequency of the one that's inside the control box and 352 00:21:06,280 --> 00:21:10,400 Speaker 1: the one that's inside the actual detector are slightly offset. 353 00:21:10,520 --> 00:21:16,160 Speaker 1: They're not in sync or backstreet boys. Oh you got 354 00:21:16,200 --> 00:21:22,040 Speaker 1: the other one I was gonna do U. So yeah, well, 355 00:21:22,080 --> 00:21:25,400 Speaker 1: ironically enough to our our current part of the conversation. 356 00:21:26,119 --> 00:21:29,240 Speaker 1: They create radio waves um, and then the receiver in 357 00:21:29,280 --> 00:21:33,000 Speaker 1: the control box uh picks that up and plays tones 358 00:21:33,680 --> 00:21:37,000 Speaker 1: to let you know when you're you're coming into range 359 00:21:37,040 --> 00:21:39,879 Speaker 1: of metal, right, Because what's happening is that when the 360 00:21:40,160 --> 00:21:46,280 Speaker 1: metal encounters this uh, this this this electromagnetic field that 361 00:21:46,600 --> 00:21:50,240 Speaker 1: is going to alter that radio wave. And so what's 362 00:21:50,359 --> 00:21:53,720 Speaker 1: really listening for our changes in the sound that you're hearing. 363 00:21:54,240 --> 00:21:56,919 Speaker 1: The change in the sound indicates that you have encountered 364 00:21:57,040 --> 00:22:00,919 Speaker 1: something that is generating this man medic field because of 365 00:22:00,920 --> 00:22:05,639 Speaker 1: the one you're generating, they know what they're going through. Um. 366 00:22:05,840 --> 00:22:09,359 Speaker 1: So yeah, I mean detectors killed the radio star. But 367 00:22:09,440 --> 00:22:12,520 Speaker 1: these these uh, Like I said, these are a lot 368 00:22:12,640 --> 00:22:16,880 Speaker 1: cheaper to manufacture. And therefore, if you are uh interested 369 00:22:16,920 --> 00:22:20,640 Speaker 1: in getting your feet wet, uh and the metal detector 370 00:22:21,200 --> 00:22:23,199 Speaker 1: the thing is a hobby, you might consider this, but 371 00:22:23,240 --> 00:22:26,560 Speaker 1: they're they're far less accurate in terms of um being 372 00:22:26,600 --> 00:22:29,800 Speaker 1: able to give you any kind of discrimination or any 373 00:22:29,840 --> 00:22:34,520 Speaker 1: really any real control. Um they actually use these are 374 00:22:34,520 --> 00:22:37,600 Speaker 1: the types of metal detectors that you the handheld detectors 375 00:22:37,600 --> 00:22:40,359 Speaker 1: that they use the airport. Um, you know, if you 376 00:22:40,400 --> 00:22:43,080 Speaker 1: walk through the scanner and and then yeah, that's the 377 00:22:43,080 --> 00:22:44,880 Speaker 1: type they use in the one because they don't really 378 00:22:44,920 --> 00:22:48,479 Speaker 1: need to know whether it's gold or iron. They just 379 00:22:48,920 --> 00:22:50,720 Speaker 1: want to know what it is that you've got now 380 00:22:50,760 --> 00:22:53,479 Speaker 1: once once, once something beeps, then they can say, all right, 381 00:22:53,480 --> 00:22:55,639 Speaker 1: well let's see what that is. They don't, you know, 382 00:22:55,760 --> 00:22:59,560 Speaker 1: necessarily need to know immediately. Yeah. And the metal detectors 383 00:22:59,640 --> 00:23:03,600 Speaker 1: the frames at the airport, they work on essentially the 384 00:23:03,600 --> 00:23:07,320 Speaker 1: same principles we've talked about here. They're generating electromagnetic fields, 385 00:23:07,320 --> 00:23:10,159 Speaker 1: which of course has brought up some concerns with people 386 00:23:10,200 --> 00:23:14,840 Speaker 1: who may have UH devices like medical devices that could 387 00:23:14,880 --> 00:23:18,199 Speaker 1: react to electromagnetic fields. That's why you'll occasionally hear about 388 00:23:18,840 --> 00:23:22,040 Speaker 1: UH folks like that having to go through like a 389 00:23:22,080 --> 00:23:25,320 Speaker 1: pat down security as opposed to a metal detector, just 390 00:23:25,359 --> 00:23:27,679 Speaker 1: because of the concern that it could interfere with a 391 00:23:27,720 --> 00:23:32,760 Speaker 1: medical device. Right right now, with with all of these um, 392 00:23:32,840 --> 00:23:36,000 Speaker 1: what you're gonna find depends on the type of metal detector, 393 00:23:36,200 --> 00:23:39,840 Speaker 1: the type of metal that you're looking for, about how 394 00:23:39,880 --> 00:23:41,760 Speaker 1: big it is, the kind of makeup of the soil, 395 00:23:42,480 --> 00:23:45,800 Speaker 1: um any kind of interference from other objects, and the halo, 396 00:23:46,320 --> 00:23:49,600 Speaker 1: which is basically, you know, if you have a piece 397 00:23:49,680 --> 00:23:53,119 Speaker 1: of metal in the soil, it's going to read a 398 00:23:53,160 --> 00:23:55,600 Speaker 1: little bit differently, it's going to it's going to register 399 00:23:55,720 --> 00:23:59,720 Speaker 1: is larger than it actually is. Yeah, because those interesting things, Yeah, 400 00:23:59,720 --> 00:24:02,560 Speaker 1: they I could see your halo. I was I was waiting. 401 00:24:02,920 --> 00:24:05,880 Speaker 1: I was trying so hard not to go into that. 402 00:24:06,280 --> 00:24:10,280 Speaker 1: We've done so many songs references in this podcast. It's crazy. 403 00:24:10,359 --> 00:24:15,200 Speaker 1: And this might be our like our most intense references 404 00:24:15,240 --> 00:24:17,280 Speaker 1: per minute other than the first one. None of them 405 00:24:17,320 --> 00:24:21,880 Speaker 1: have been metal. That's true. That's true. So, but yeah, 406 00:24:21,960 --> 00:24:24,080 Speaker 1: now that it is, really the halo effect is really 407 00:24:24,080 --> 00:24:27,919 Speaker 1: an interesting thing. It's just this the fact that certain 408 00:24:28,000 --> 00:24:33,080 Speaker 1: kinds of metal objects can actually increase the conductivity of 409 00:24:33,160 --> 00:24:36,000 Speaker 1: the soil that's around them. And the longer that object, 410 00:24:36,280 --> 00:24:39,120 Speaker 1: those particular objects have been in the ground, the greater 411 00:24:39,680 --> 00:24:42,760 Speaker 1: that conductivity change can be. So then yeah, you might 412 00:24:42,800 --> 00:24:45,920 Speaker 1: be like, hey, there's a there's a Sherman tank down 413 00:24:45,960 --> 00:24:48,320 Speaker 1: there or something, and it just turns out that there's 414 00:24:48,359 --> 00:24:50,760 Speaker 1: another object that's been down there and has affected the 415 00:24:50,760 --> 00:24:54,119 Speaker 1: conductivity of the soil. Um that's pretty phenomenal. If you 416 00:24:54,160 --> 00:24:56,480 Speaker 1: have a Sherman tank buried in your backyard, please give 417 00:24:56,480 --> 00:25:00,640 Speaker 1: me a call. I'm I'm interested to well, not anymore. Yeah, 418 00:25:00,640 --> 00:25:02,480 Speaker 1: I mean, well, you think about it. It It makes sense 419 00:25:02,520 --> 00:25:05,240 Speaker 1: if you have let's say, let's say the aforementioned screw 420 00:25:05,800 --> 00:25:08,040 Speaker 1: and it's been there for a couple of years. It's 421 00:25:08,600 --> 00:25:11,879 Speaker 1: let's say iron, and it's beginning to rust, it's beginning 422 00:25:11,880 --> 00:25:16,000 Speaker 1: to disintegrate, and you can change the conduct conductivity depending 423 00:25:16,000 --> 00:25:19,840 Speaker 1: on the Again, it also depends it's rain then, you know, yeah, 424 00:25:19,840 --> 00:25:22,119 Speaker 1: it really depends upon the composition of the soil. Itself 425 00:25:22,160 --> 00:25:24,359 Speaker 1: as well. So, yeah, if there's a lot of iron 426 00:25:24,400 --> 00:25:27,840 Speaker 1: content in the soil, that's gonna cause some issues when 427 00:25:27,840 --> 00:25:29,800 Speaker 1: you're when you're doing metal detection. You know, you're just 428 00:25:30,240 --> 00:25:32,000 Speaker 1: you're gonna get a lot of interference and you just 429 00:25:32,040 --> 00:25:34,360 Speaker 1: have to factor that in. Doesn't mean that the metal 430 00:25:34,440 --> 00:25:36,159 Speaker 1: detector is going to be useless. It just means that 431 00:25:36,240 --> 00:25:40,159 Speaker 1: you have to kind of adjust your expectations and listen 432 00:25:40,240 --> 00:25:44,560 Speaker 1: for bigger changes in UH in the soil content and 433 00:25:44,720 --> 00:25:48,440 Speaker 1: not and kind of kind of ignore the noise, separate 434 00:25:48,480 --> 00:25:50,840 Speaker 1: the signal from the noise. Yeah, I would argue that 435 00:25:50,880 --> 00:25:54,520 Speaker 1: it probably takes some personal discrimination too. You really need 436 00:25:54,560 --> 00:25:56,480 Speaker 1: to get out there in practice if you're going to 437 00:25:56,520 --> 00:26:00,480 Speaker 1: start using doing metal detecting as a hobby, um, and 438 00:26:00,640 --> 00:26:02,720 Speaker 1: maybe even trying it with things that you what that 439 00:26:02,800 --> 00:26:06,360 Speaker 1: you know what they are, you know, some coins, a ring, 440 00:26:07,320 --> 00:26:11,479 Speaker 1: a screwdriver, you know, something that hammers, you know, Sherman tanks, 441 00:26:12,440 --> 00:26:14,400 Speaker 1: the stuff that you do, you know, tend to run 442 00:26:14,440 --> 00:26:16,960 Speaker 1: across in your general area. Well, you know, you never 443 00:26:17,000 --> 00:26:18,560 Speaker 1: know what you're gonna find when you're out in the 444 00:26:18,640 --> 00:26:21,600 Speaker 1: field somewhere, and if you can identify what they are, 445 00:26:21,640 --> 00:26:24,879 Speaker 1: you can get a sense of what different metals sound like. 446 00:26:24,960 --> 00:26:27,840 Speaker 1: How get a feel for how your metal detector works, 447 00:26:28,160 --> 00:26:32,240 Speaker 1: how sensitive it is, and how sensitive it is. Um, yeah, 448 00:26:32,320 --> 00:26:34,040 Speaker 1: it can be a lot of fun to uh, as 449 00:26:34,040 --> 00:26:37,640 Speaker 1: you were talking about before, like going to uh battlefields. 450 00:26:37,640 --> 00:26:41,440 Speaker 1: Of course, I imagine probably all the major battlefields have 451 00:26:41,520 --> 00:26:44,320 Speaker 1: been picked pretty clean at this point, you think, But 452 00:26:44,400 --> 00:26:48,520 Speaker 1: it's it's amazing once you can stumble across It's again, 453 00:26:48,520 --> 00:26:50,439 Speaker 1: it's one of those things where it may be it 454 00:26:50,480 --> 00:26:55,000 Speaker 1: may require a phenomenal amount of luck. Sure experience, there's 455 00:26:55,000 --> 00:26:58,159 Speaker 1: no such thing as luck, but it may require a 456 00:26:58,160 --> 00:27:01,080 Speaker 1: phenomenal a series of incidences in order for you to 457 00:27:01,119 --> 00:27:04,159 Speaker 1: stumble across the right section to find something significant. But 458 00:27:04,920 --> 00:27:08,600 Speaker 1: really you never know. You just it's it's amazing to 459 00:27:08,680 --> 00:27:11,040 Speaker 1: me how something that you would think, oh, well, this 460 00:27:11,119 --> 00:27:13,880 Speaker 1: has got so much traffic, there's no way there's anything 461 00:27:13,880 --> 00:27:16,280 Speaker 1: of significance can be found there. And yet like five 462 00:27:16,359 --> 00:27:19,679 Speaker 1: years later you'll find that the find of this injury. 463 00:27:20,000 --> 00:27:22,760 Speaker 1: How did that happen? But yeah, and you don't know 464 00:27:23,160 --> 00:27:28,159 Speaker 1: what's around in places that you know might be a value. 465 00:27:28,160 --> 00:27:30,760 Speaker 1: I mean again, people find I'm still searching for black 466 00:27:30,760 --> 00:27:33,639 Speaker 1: Beard's treasure. All kinds of stuff out in time, I 467 00:27:33,680 --> 00:27:37,600 Speaker 1: go to the Carolinas out in normal places. Maybe I 468 00:27:37,640 --> 00:27:41,240 Speaker 1: should actually go to the everyday beach instead of in London. 469 00:27:41,320 --> 00:27:45,280 Speaker 1: That's probably part of the problem. Yeah, you know, Charleston 470 00:27:45,400 --> 00:27:47,000 Speaker 1: is so nice. I just like to, you know, spend 471 00:27:47,000 --> 00:27:51,880 Speaker 1: some time there enough. Yeah, people even use them for prospecting, 472 00:27:52,640 --> 00:27:54,920 Speaker 1: you know, and uh and for coin shooting. Now, if 473 00:27:54,920 --> 00:27:57,359 Speaker 1: you do want to use your mail detective for prospecting, 474 00:27:57,359 --> 00:28:00,399 Speaker 1: there are some things you need to remember. First, you 475 00:28:00,440 --> 00:28:04,119 Speaker 1: have to grow a fear of at least a foot 476 00:28:04,119 --> 00:28:06,560 Speaker 1: in length. That needs to be gray and grizzly. He's 477 00:28:06,600 --> 00:28:08,960 Speaker 1: gonna punchy ladies and gentlemen. Second, you need to be 478 00:28:08,960 --> 00:28:11,639 Speaker 1: able to say things like consarnate with a straight face. 479 00:28:11,880 --> 00:28:14,280 Speaker 1: And then third, the most important thing about being a 480 00:28:14,320 --> 00:28:16,639 Speaker 1: prospector is you have to develop your crazy prospect or 481 00:28:16,720 --> 00:28:21,440 Speaker 1: dance when you strike gold. Very important. Yeah. Coin shooting 482 00:28:21,760 --> 00:28:25,640 Speaker 1: is uh the practice of looking for coins after an 483 00:28:25,640 --> 00:28:29,840 Speaker 1: outdoor event like a wedding or or like stock you 484 00:28:29,840 --> 00:28:31,919 Speaker 1: go to you go to some big outdoor conference and 485 00:28:32,000 --> 00:28:35,320 Speaker 1: you take a male detector and you start looking for 486 00:28:35,320 --> 00:28:37,679 Speaker 1: for change. The thing is that if you live in 487 00:28:37,680 --> 00:28:39,440 Speaker 1: an area where this sort of stuff goes on in 488 00:28:39,440 --> 00:28:42,880 Speaker 1: a regular basis, you could presumably pay off that mel 489 00:28:43,000 --> 00:28:47,920 Speaker 1: detector after you know, a few visits to these these 490 00:28:47,960 --> 00:28:53,320 Speaker 1: areas once the concert is over or a game or whatever. Um, 491 00:28:53,400 --> 00:28:56,880 Speaker 1: you know. And and because we're usually talking about change, 492 00:28:57,200 --> 00:29:00,520 Speaker 1: you know, some some nickels or dimes or quarters or whatever, 493 00:29:00,720 --> 00:29:03,280 Speaker 1: but whatever money you use, because you know, it's not 494 00:29:03,320 --> 00:29:07,280 Speaker 1: all just United States folks. Well, if you find euros, 495 00:29:07,280 --> 00:29:10,000 Speaker 1: you're rich, because I think a euro is equivalent to 496 00:29:10,040 --> 00:29:14,840 Speaker 1: like seventeen dollars at this point. Um, that's a gross exaggeration, 497 00:29:15,640 --> 00:29:18,720 Speaker 1: but the point being that, you know, yeah, you could 498 00:29:18,720 --> 00:29:24,440 Speaker 1: conceivably pay off your mail detectors costs after a few visits, 499 00:29:24,600 --> 00:29:27,920 Speaker 1: you know. Um. But although a lot of people just 500 00:29:28,040 --> 00:29:30,360 Speaker 1: enjoy the this as a hobby, like it's just it's 501 00:29:30,360 --> 00:29:33,960 Speaker 1: a way to get outside. You're enjoying your joying time 502 00:29:34,040 --> 00:29:37,280 Speaker 1: outdoors and you're finding stuff which just brings you a 503 00:29:37,400 --> 00:29:41,520 Speaker 1: level of of of satisfaction, right. It means that whole 504 00:29:41,520 --> 00:29:44,800 Speaker 1: treasure hunting aspect, you know, when I when we discover something, 505 00:29:44,840 --> 00:29:47,080 Speaker 1: there's an element of satisfaction there that you can't put 506 00:29:47,080 --> 00:29:51,520 Speaker 1: a monetary value on. Yeah, yeah, you're just like, hey, 507 00:29:51,520 --> 00:29:55,240 Speaker 1: look I found some money woo, And yeah, there's there's 508 00:29:55,280 --> 00:29:58,400 Speaker 1: an enjoyment level there that goes beyond. Oh and it's 509 00:29:58,400 --> 00:30:02,800 Speaker 1: worth you know, seventy five cents. Yes, um, although the cents, 510 00:30:02,800 --> 00:30:05,440 Speaker 1: it's always nice to have seventy five cents more than 511 00:30:05,480 --> 00:30:07,320 Speaker 1: you had, but when you showed up at the field. 512 00:30:07,640 --> 00:30:12,520 Speaker 1: So yeah, I keep wondering, actually, why the value of 513 00:30:12,560 --> 00:30:16,480 Speaker 1: the giant jar of class rings. You'd figure they'd cash 514 00:30:16,560 --> 00:30:18,960 Speaker 1: that in. Yeah, I mean for more than just selling 515 00:30:18,960 --> 00:30:22,000 Speaker 1: metal detectors. Maybe that's more lucrative than selling off some 516 00:30:22,040 --> 00:30:23,920 Speaker 1: of those classroom you have, prying out all the little 517 00:30:24,000 --> 00:30:27,280 Speaker 1: jewels and melting that stuff down and then just hey, 518 00:30:27,280 --> 00:30:29,200 Speaker 1: you know, how can yourself bar a gold? It's worth 519 00:30:29,280 --> 00:30:32,480 Speaker 1: its weight in gold. Anyway, I need to go out 520 00:30:32,480 --> 00:30:35,200 Speaker 1: and get a mel detector. Yeah they're fun, Yeah they 521 00:30:35,200 --> 00:30:37,200 Speaker 1: could be. They could be a lot of fun. Yeah, definitely. 522 00:30:37,280 --> 00:30:40,400 Speaker 1: So anyway, that that kind of sums up this podcast 523 00:30:40,440 --> 00:30:42,840 Speaker 1: on how mel detectors work. Remember, we do have an 524 00:30:42,960 --> 00:30:46,080 Speaker 1: article on the website that goes into more detail and 525 00:30:46,160 --> 00:30:48,400 Speaker 1: kind of walks you through what we've talked about here. 526 00:30:48,760 --> 00:30:51,760 Speaker 1: I highly recommend it. If you guys have any technology 527 00:30:51,800 --> 00:30:55,280 Speaker 1: you would want us to talk about, please let us know. 528 00:30:55,720 --> 00:30:57,800 Speaker 1: You can drop us a line on Facebook or Twitter, 529 00:30:57,840 --> 00:31:01,280 Speaker 1: are handled there as tech Stuff hs W, or send 530 00:31:01,360 --> 00:31:04,560 Speaker 1: us an email. That address is tech stuff at how 531 00:31:04,640 --> 00:31:06,760 Speaker 1: stuff works dot com. Chris and I will talk to 532 00:31:06,760 --> 00:31:11,880 Speaker 1: you again beep really soon. Be sure to check out 533 00:31:11,920 --> 00:31:15,080 Speaker 1: our new video podcast, Stuff from the Future. Join how 534 00:31:15,120 --> 00:31:17,680 Speaker 1: Stuff Work staff as we explore the most promising and 535 00:31:17,720 --> 00:31:22,400 Speaker 1: perplexing possibilities us tomorrow. The How Stuff Works iPhone app 536 00:31:22,440 --> 00:31:30,120 Speaker 1: has arrived. Download it today on iTunes, brought to you 537 00:31:30,160 --> 00:31:33,520 Speaker 1: by the reinvented two thousand twelve camera. It's ready, are 538 00:31:33,600 --> 00:31:33,760 Speaker 1: you