1 00:00:04,320 --> 00:00:10,640 Speaker 1: Welcome to Tech Stuff, a production of Iheartradios How Stuff Works. 2 00:00:12,240 --> 00:00:14,800 Speaker 1: Hey there, and welcome to tech Stuff. I'm your host, 3 00:00:14,920 --> 00:00:18,560 Speaker 1: Jonathan Strickland. I'm an executive producer with iHeart Podcasts and 4 00:00:18,720 --> 00:00:22,599 Speaker 1: how the Tech are you. Well, I'm still vacating, which 5 00:00:22,640 --> 00:00:27,440 Speaker 1: means I'm off in Florida being a crazy tourist type person. 6 00:00:28,000 --> 00:00:31,080 Speaker 1: And in the meantime, I have an episode for you 7 00:00:31,320 --> 00:00:34,519 Speaker 1: that we publish back on February tenth, twenty twenty. This 8 00:00:34,520 --> 00:00:37,080 Speaker 1: one is titled How Smoke Detectors Work. I figured it 9 00:00:37,120 --> 00:00:39,480 Speaker 1: was a good idea to do an episode about smoke 10 00:00:39,520 --> 00:00:41,560 Speaker 1: detectors as we go toward the end of the year, 11 00:00:41,600 --> 00:00:46,320 Speaker 1: because I've always tried to change out the batteries and 12 00:00:46,400 --> 00:00:50,080 Speaker 1: my smoke detectors at the beginning of each year, because 13 00:00:50,120 --> 00:00:52,080 Speaker 1: otherwise I just would forget to do it. But by 14 00:00:52,120 --> 00:00:55,080 Speaker 1: making it like, hey, happy New Year, you gotta change 15 00:00:55,120 --> 00:00:58,640 Speaker 1: out all the smoke detector batteries, I am less likely 16 00:00:58,680 --> 00:01:01,280 Speaker 1: to forget. But how did those darned things work in 17 00:01:01,320 --> 00:01:06,920 Speaker 1: the first place. Well, let's listen and find out. Now. Clearly, 18 00:01:07,360 --> 00:01:11,759 Speaker 1: smoke detectors are incredibly important because we all know fires 19 00:01:11,800 --> 00:01:15,000 Speaker 1: can be life threatening. They can spread quickly, they can 20 00:01:15,040 --> 00:01:17,600 Speaker 1: cut off potential escape routes for the people who are 21 00:01:17,680 --> 00:01:20,600 Speaker 1: caught in the way. So early warning systems that can 22 00:01:20,640 --> 00:01:24,320 Speaker 1: alert us to danger before it becomes a mortal danger 23 00:01:24,440 --> 00:01:28,400 Speaker 1: are fantastic inventions. And there are a couple of inventions 24 00:01:28,440 --> 00:01:30,959 Speaker 1: I want to talk about before we actually get to 25 00:01:31,040 --> 00:01:34,120 Speaker 1: smoke detectors. I'm sure that doesn't come as a surprise 26 00:01:34,160 --> 00:01:36,320 Speaker 1: to any of you who have listened to Tech Stuff 27 00:01:36,319 --> 00:01:39,319 Speaker 1: episodes before. I always like to set the ground well. 28 00:01:39,440 --> 00:01:41,399 Speaker 1: The first one that I want to talk about is 29 00:01:41,440 --> 00:01:45,600 Speaker 1: the portable electric fire alarm, as in a fire alarm 30 00:01:45,640 --> 00:01:48,800 Speaker 1: that works on electricity, not a fire alarm that detects 31 00:01:48,840 --> 00:01:53,040 Speaker 1: electric fires. Francis robins Upton, who is a physicist who 32 00:01:53,120 --> 00:01:56,960 Speaker 1: was a partner and general manager of the Edison Lamp Works, 33 00:01:57,440 --> 00:02:01,720 Speaker 1: as in Thomas Edison, developed this particular invention back in 34 00:02:01,800 --> 00:02:06,080 Speaker 1: eighteen ninety. Now, according to the patent, the design would 35 00:02:06,120 --> 00:02:10,280 Speaker 1: sound an alarm after detecting that the temperature had risen 36 00:02:10,440 --> 00:02:14,520 Speaker 1: above some predetermined limit, so if it got too hot, 37 00:02:15,120 --> 00:02:17,960 Speaker 1: this thing would go off. And the way this would 38 00:02:18,040 --> 00:02:21,160 Speaker 1: work was really clever. You can actually learn exactly how 39 00:02:21,160 --> 00:02:24,320 Speaker 1: it was supposed to work based on the patent that 40 00:02:24,560 --> 00:02:29,640 Speaker 1: Upton got on this particular invention. So the way it 41 00:02:29,680 --> 00:02:33,080 Speaker 1: works is that there are a pair of electrical contacts 42 00:02:33,639 --> 00:02:36,160 Speaker 1: and if they are in contact with each other, if 43 00:02:36,200 --> 00:02:39,720 Speaker 1: they touch each other, it completes a circuit. But normally 44 00:02:40,120 --> 00:02:43,639 Speaker 1: there's a gap between them and electricity can't pass between 45 00:02:43,760 --> 00:02:47,560 Speaker 1: the two. It can't cross that gap, so it's normally 46 00:02:47,600 --> 00:02:51,280 Speaker 1: in the off position. However, one of those two electrical 47 00:02:51,400 --> 00:02:56,080 Speaker 1: contacts is mounted on a fixed arm and the other 48 00:02:56,400 --> 00:02:59,400 Speaker 1: is on an arm that's attached to a coil of 49 00:02:59,480 --> 00:03:04,440 Speaker 1: biomet hallick material. Now I mentioned biometallic strips in the 50 00:03:04,480 --> 00:03:07,400 Speaker 1: episode about lighters, and it's something you find in a 51 00:03:07,440 --> 00:03:12,280 Speaker 1: lot of different technologies that depend upon changes in temperature 52 00:03:12,720 --> 00:03:17,240 Speaker 1: as a variable, like thermostats have bimetallic strips in them. 53 00:03:17,560 --> 00:03:20,040 Speaker 1: And essentially what it is is a strip of metal 54 00:03:20,280 --> 00:03:24,120 Speaker 1: that consists of two different metals. And think of it 55 00:03:24,160 --> 00:03:26,880 Speaker 1: as like a metal sandwich, a top side and a 56 00:03:26,919 --> 00:03:30,480 Speaker 1: bottom side, and one metal is the top side, the 57 00:03:30,520 --> 00:03:33,560 Speaker 1: other metal is the bottom side, and each metal has 58 00:03:33,600 --> 00:03:37,040 Speaker 1: slightly different properties, and one of those properties is how 59 00:03:37,120 --> 00:03:40,640 Speaker 1: quickly they expand when they're heated up. You know, we 60 00:03:40,760 --> 00:03:43,560 Speaker 1: know that metal expands as it gets warmer. Well, using 61 00:03:43,560 --> 00:03:46,640 Speaker 1: a bimetallic strip, you have one side that will expand 62 00:03:46,720 --> 00:03:50,360 Speaker 1: faster than the other side, and when that happens, it 63 00:03:50,440 --> 00:03:54,920 Speaker 1: causes the strip to curl, so it deforms. As it 64 00:03:54,960 --> 00:03:58,839 Speaker 1: gets warmer, one side is expanding faster than the other 65 00:03:59,360 --> 00:04:02,640 Speaker 1: and you get this curled metal as a result. So 66 00:04:02,760 --> 00:04:07,240 Speaker 1: with Upton's proposed invention in the patent, this coil of 67 00:04:07,320 --> 00:04:11,120 Speaker 1: bimetallic material would act as sort of an actuator. As 68 00:04:11,200 --> 00:04:14,520 Speaker 1: it would get warm, it would expand, and this in 69 00:04:14,560 --> 00:04:18,440 Speaker 1: turn would create a pushing force on the arm with 70 00:04:18,640 --> 00:04:21,960 Speaker 1: the electrical contact on it that then can move toward 71 00:04:22,160 --> 00:04:25,520 Speaker 1: the other electrical contact that's in a fixed position. And 72 00:04:25,600 --> 00:04:29,680 Speaker 1: so once the coil had expanded enough, the two contacts 73 00:04:29,760 --> 00:04:33,480 Speaker 1: would touch one another and it would complete a circuit. 74 00:04:33,880 --> 00:04:37,479 Speaker 1: At that point, electrical current could actually flow from a 75 00:04:37,520 --> 00:04:40,680 Speaker 1: battery that was connected to this device all the way 76 00:04:40,720 --> 00:04:44,680 Speaker 1: through to activate an alarm bell. So once the temperature 77 00:04:44,680 --> 00:04:48,120 Speaker 1: got hot enough the two contacts touch, you get a circuit. 78 00:04:48,400 --> 00:04:50,800 Speaker 1: The alarm bell goes off. If it cools down, the 79 00:04:50,839 --> 00:04:55,200 Speaker 1: contacts will slowly separate, and eventually they'll separate enough where 80 00:04:55,240 --> 00:04:58,800 Speaker 1: that electrical circuit can't be complete. Anymore, the alarm bell 81 00:04:58,839 --> 00:05:02,560 Speaker 1: would go off. And Upton's invention was, without doubt a 82 00:05:02,680 --> 00:05:06,520 Speaker 1: very clever one, and it could help save property by 83 00:05:06,560 --> 00:05:09,680 Speaker 1: sounding an alarm before a fire had raged completely out 84 00:05:09,680 --> 00:05:14,680 Speaker 1: of control. But there are many dangers with fires, and 85 00:05:14,800 --> 00:05:18,600 Speaker 1: heat is just one of them. Another very serious danger 86 00:05:18,760 --> 00:05:22,320 Speaker 1: is smoke, which not only obscures your vision, but it 87 00:05:22,360 --> 00:05:25,960 Speaker 1: also can suffocate you as well. So while the alarm 88 00:05:26,080 --> 00:05:30,159 Speaker 1: as design would work, it wouldn't necessarily be enough to 89 00:05:30,279 --> 00:05:34,679 Speaker 1: save lives, or it might not save enough lives because 90 00:05:34,720 --> 00:05:36,960 Speaker 1: it would only go into action after the temperature had 91 00:05:37,000 --> 00:05:40,960 Speaker 1: already increased enough to make this bimetallic strip expand to 92 00:05:41,000 --> 00:05:44,760 Speaker 1: a sufficient degree, and by that time it might already 93 00:05:44,760 --> 00:05:47,720 Speaker 1: be too late for the people in that building. Now, 94 00:05:47,760 --> 00:05:51,320 Speaker 1: as far as I know, Edison's company didn't actually produce 95 00:05:51,480 --> 00:05:54,040 Speaker 1: any of these fire alarms, but they did patent it. 96 00:05:54,640 --> 00:05:57,320 Speaker 1: Over in Great Britain, there was a fellow named George 97 00:05:57,360 --> 00:06:01,440 Speaker 1: Andrew Darby who patented his own fire alarm, also triggered 98 00:06:01,520 --> 00:06:05,400 Speaker 1: by an increase in temperature. But Darby's invention did not 99 00:06:05,680 --> 00:06:11,440 Speaker 1: depend upon bimetallic strips. It depended on butter or some 100 00:06:11,560 --> 00:06:16,520 Speaker 1: other material that melts at higher temperatures. Say what, all right, 101 00:06:16,640 --> 00:06:21,159 Speaker 1: So imagine you've got a seesaw like contraption, a lever 102 00:06:21,320 --> 00:06:24,039 Speaker 1: in other words, and the heavy end of the lever 103 00:06:25,160 --> 00:06:28,640 Speaker 1: is up in the air actually because you have a 104 00:06:28,680 --> 00:06:31,360 Speaker 1: weight on the opposite end of that lever. So it's 105 00:06:31,400 --> 00:06:33,599 Speaker 1: like a kid sitting on a seesaw that doesn't have 106 00:06:33,680 --> 00:06:36,200 Speaker 1: another kid at the end of it. The kid at 107 00:06:36,200 --> 00:06:38,600 Speaker 1: the end of the sea saw weighs it down, and 108 00:06:38,640 --> 00:06:41,920 Speaker 1: the free end of the seesaw is up in the air. Well, 109 00:06:41,920 --> 00:06:45,880 Speaker 1: in this case, the fire alarms seesaw. The arm that's 110 00:06:45,960 --> 00:06:48,560 Speaker 1: up in the air has an electrical contact point on it, 111 00:06:48,839 --> 00:06:52,120 Speaker 1: and if the arm of the seesaw were to come down, 112 00:06:52,839 --> 00:06:58,479 Speaker 1: that contact would complete a circuit, and thus electricity would 113 00:06:58,480 --> 00:07:00,919 Speaker 1: be able to run from a battery through an alarm, 114 00:07:01,040 --> 00:07:05,480 Speaker 1: very much like Upton's invention. So weighing down the other 115 00:07:05,600 --> 00:07:07,640 Speaker 1: end of the arm. The thing that's actually keeping the 116 00:07:07,680 --> 00:07:10,960 Speaker 1: electrical contact up in the air is a block of 117 00:07:11,040 --> 00:07:15,320 Speaker 1: butter or fat or wax or some other material that 118 00:07:15,360 --> 00:07:19,160 Speaker 1: can melt at higher temperatures. So as the temperature rises, 119 00:07:19,640 --> 00:07:22,800 Speaker 1: the block begins to melt away, and eventually it melts 120 00:07:22,920 --> 00:07:26,040 Speaker 1: enough so that the weight isn't sufficient to keep the 121 00:07:26,080 --> 00:07:28,160 Speaker 1: other end of the seesaw up in the air, and 122 00:07:28,240 --> 00:07:31,400 Speaker 1: it'll sink down and the contact will complete the circuit 123 00:07:31,640 --> 00:07:34,600 Speaker 1: and the alarm will go off. I was amused to 124 00:07:34,800 --> 00:07:38,240 Speaker 1: find a butter based fire alarm. I wasn't surprised that 125 00:07:38,280 --> 00:07:40,120 Speaker 1: it came out of England, but I was amused to 126 00:07:40,160 --> 00:07:42,680 Speaker 1: find it. I can think of a few potential problems 127 00:07:42,760 --> 00:07:46,480 Speaker 1: with such an arrangement. For example, it might start attracting 128 00:07:46,560 --> 00:07:51,040 Speaker 1: pests that could eat the weight, so in those cases 129 00:07:51,080 --> 00:07:53,480 Speaker 1: you wouldn't actually have a fire alarm, but you might 130 00:07:53,520 --> 00:07:57,400 Speaker 1: have a rat alarm, or it would just turn rancid 131 00:07:57,520 --> 00:08:02,480 Speaker 1: and smell offul Still a pretty clever approach, but not 132 00:08:02,600 --> 00:08:04,880 Speaker 1: one that I think you would actually want to put 133 00:08:04,960 --> 00:08:09,480 Speaker 1: in your buildings. But these solutions weren't practical for homes 134 00:08:09,720 --> 00:08:12,160 Speaker 1: or anything like that. As I mentioned, they wouldn't really 135 00:08:12,160 --> 00:08:14,400 Speaker 1: alert you to the presence of smoke, which on its 136 00:08:14,400 --> 00:08:17,040 Speaker 1: own would be enough to be deadly. So this was 137 00:08:17,080 --> 00:08:20,000 Speaker 1: really looked at as more of a solution for things 138 00:08:20,080 --> 00:08:24,440 Speaker 1: like factories facilities, where you've got a lot of industrial 139 00:08:24,520 --> 00:08:27,440 Speaker 1: operations going on, where the risk of fire is high 140 00:08:27,880 --> 00:08:31,679 Speaker 1: and the risk of property loss is also high smoke 141 00:08:31,760 --> 00:08:36,680 Speaker 1: detectors also trace their history back to chemists, physicists, and inventors, 142 00:08:36,960 --> 00:08:39,439 Speaker 1: and in fact, you could say that smoke detectors were 143 00:08:39,520 --> 00:08:44,680 Speaker 1: made possible not just through exploratory science, but also happy accidents. 144 00:08:45,200 --> 00:08:48,520 Speaker 1: And will begin with a super smart Swiss physicist in 145 00:08:48,600 --> 00:08:52,840 Speaker 1: the early twentieth century and try saying that three times fast. 146 00:08:52,960 --> 00:09:00,640 Speaker 1: Super smart Swiss physicist. His name was Heinrich Grinecker or 147 00:09:00,679 --> 00:09:04,400 Speaker 1: Grindacre if you prefer study a lot of different stuff, 148 00:09:04,480 --> 00:09:09,160 Speaker 1: including radioactivity. Wilhelm Runtgen had discovered the existence of X 149 00:09:09,280 --> 00:09:13,439 Speaker 1: rays in eighteen ninety five, and Grindacre devoted a good 150 00:09:13,440 --> 00:09:17,000 Speaker 1: deal of his work toward getting a better understanding of 151 00:09:17,640 --> 00:09:20,160 Speaker 1: X rays and other forms of radiation, and to do 152 00:09:20,200 --> 00:09:23,920 Speaker 1: that he had to overcome some practical obstacles. For example, 153 00:09:24,200 --> 00:09:26,800 Speaker 1: he needed a device to help measure the intensity of 154 00:09:27,000 --> 00:09:30,040 Speaker 1: X rays, and such a device didn't really exist yet, 155 00:09:30,120 --> 00:09:33,400 Speaker 1: so he got to work inventing one. X rays are 156 00:09:33,440 --> 00:09:37,199 Speaker 1: a type of ionizing radiation that means that when they 157 00:09:37,320 --> 00:09:42,120 Speaker 1: encounter molecules or atoms, they can ionize them. And an 158 00:09:42,160 --> 00:09:45,040 Speaker 1: ion is a molecule or an atom that has a 159 00:09:45,080 --> 00:09:49,599 Speaker 1: net electrical charge, so it's either a positive particle or 160 00:09:49,679 --> 00:09:53,120 Speaker 1: a negative particle. And a positive ion is one that 161 00:09:53,160 --> 00:09:56,560 Speaker 1: has more protons than electrons, so you have a net 162 00:09:56,640 --> 00:09:59,080 Speaker 1: positive charge. A negative ion would be the opposite, has 163 00:09:59,120 --> 00:10:03,120 Speaker 1: more electrons than protons and has a net negative charge. Now, 164 00:10:03,160 --> 00:10:07,920 Speaker 1: one thing Grindacre did was to create ions by building 165 00:10:07,960 --> 00:10:11,319 Speaker 1: a grid of wires through which he could stream high 166 00:10:11,440 --> 00:10:16,199 Speaker 1: voltage current. And you would pass air molecules essentially through 167 00:10:16,280 --> 00:10:21,679 Speaker 1: this grid, and the current would strip electrons off of 168 00:10:21,760 --> 00:10:26,200 Speaker 1: those particles, creating positive ions. So the grid was in 169 00:10:26,240 --> 00:10:29,520 Speaker 1: this chamber through which gas could move, and as I said, 170 00:10:29,520 --> 00:10:32,240 Speaker 1: the current would ionize the gas. But the other really 171 00:10:32,280 --> 00:10:35,720 Speaker 1: neat thing he did was he invented a voltage multiplier 172 00:10:35,920 --> 00:10:39,640 Speaker 1: circuit because he needed to generate this really high voltage 173 00:10:40,240 --> 00:10:43,120 Speaker 1: around two hundred and twenty volts actually, and that could 174 00:10:43,160 --> 00:10:48,800 Speaker 1: take incoming alternating current electricity. That's the type of electricity 175 00:10:48,880 --> 00:10:52,040 Speaker 1: that power plants typically send out because it's easier to 176 00:10:52,080 --> 00:10:56,400 Speaker 1: send out alternating current over long distances than direct current. Well, 177 00:10:57,240 --> 00:11:01,280 Speaker 1: Grindacre's invention would bring in alternating current and then convert 178 00:11:01,280 --> 00:11:04,079 Speaker 1: it to direct current and run the direct current through 179 00:11:04,120 --> 00:11:07,080 Speaker 1: a circuit with stuff like capacitors and diodes, and the 180 00:11:07,080 --> 00:11:11,080 Speaker 1: whole process is a bit complicated to explain, particularly without 181 00:11:11,080 --> 00:11:13,760 Speaker 1: the use of visual aids, And also it goes beyond 182 00:11:14,000 --> 00:11:16,200 Speaker 1: today's topic. But in the future I will have to 183 00:11:16,200 --> 00:11:20,400 Speaker 1: talk about voltage multiplying circuits more specifically, because they are 184 00:11:20,440 --> 00:11:23,880 Speaker 1: important in all sorts of technologies, including super cool bleeding 185 00:11:24,000 --> 00:11:27,240 Speaker 1: edge science stuff like particle accelerators. But for the purposes 186 00:11:27,280 --> 00:11:29,120 Speaker 1: of this episode, the important thing to remember is that 187 00:11:29,440 --> 00:11:33,839 Speaker 1: it made it possible for Grindacher to create an ionization chamber. Now, 188 00:11:34,160 --> 00:11:38,120 Speaker 1: Grinacre's concern was radioactivity, and so we're going to leave 189 00:11:38,200 --> 00:11:40,800 Speaker 1: off his part of the story at this point because 190 00:11:41,120 --> 00:11:44,920 Speaker 1: that was his big contribution, was creating a feasible way 191 00:11:44,960 --> 00:11:48,559 Speaker 1: to make an ionization chamber. We need to focus more 192 00:11:48,559 --> 00:11:51,280 Speaker 1: on the folks who actually made the first smoke detectors. 193 00:11:52,040 --> 00:11:54,560 Speaker 1: Maybe I'll do a full episode about Grindacre and other 194 00:11:54,679 --> 00:11:57,520 Speaker 1: early physicists in the future, since their work would lead 195 00:11:57,520 --> 00:12:00,840 Speaker 1: to a deeper understanding of atomic physics and by extension, 196 00:12:00,920 --> 00:12:03,040 Speaker 1: quantum physics. But for now, we're going to get back 197 00:12:03,080 --> 00:12:06,280 Speaker 1: to smoke alarms. So that brings us to our next 198 00:12:06,320 --> 00:12:11,160 Speaker 1: Swiss smarty pants person, Walter Jaeger. Now back in nineteen thirty, 199 00:12:11,600 --> 00:12:15,400 Speaker 1: Yeager wasn't setting out to build a smoke detector. That 200 00:12:15,559 --> 00:12:19,480 Speaker 1: wasn't his goal. Instead, he had developed a hypothesis. He 201 00:12:19,559 --> 00:12:23,400 Speaker 1: thought that perhaps using a device with an ionization chamber 202 00:12:23,520 --> 00:12:26,199 Speaker 1: like the one Grindacre had made, he could build a 203 00:12:26,360 --> 00:12:30,040 Speaker 1: poison gas detector. So how did he think he could 204 00:12:30,080 --> 00:12:33,080 Speaker 1: do this? Well, this gets into how smoke detectors actually work, 205 00:12:33,160 --> 00:12:35,880 Speaker 1: so we're going to dive into it, all right. So, 206 00:12:36,080 --> 00:12:38,960 Speaker 1: as I said before, you've got your ionized particles. That's 207 00:12:39,000 --> 00:12:42,319 Speaker 1: a basic component of a large number of smoke detectors. 208 00:12:42,400 --> 00:12:45,160 Speaker 1: There's actually a different type of smoke detector that doesn't 209 00:12:45,280 --> 00:12:48,200 Speaker 1: use an ionization chamber at all, but i'll cover that 210 00:12:48,320 --> 00:12:52,560 Speaker 1: later in this episode. So, these ionized particles are positively charged. 211 00:12:52,720 --> 00:12:55,120 Speaker 1: They've had electrons stripped off of them, so they have 212 00:12:55,200 --> 00:12:59,920 Speaker 1: more protons than electrons. They're positively charged. A battery can 213 00:13:00,280 --> 00:13:04,360 Speaker 1: to two metal plates creates a positively charged surface on 214 00:13:04,360 --> 00:13:08,000 Speaker 1: one side and a negatively charged surface on the other side. 215 00:13:08,320 --> 00:13:13,360 Speaker 1: So the electrons that are stripped away from the molecules 216 00:13:13,679 --> 00:13:17,400 Speaker 1: will then move to the positively charged plate, and the 217 00:13:17,440 --> 00:13:20,480 Speaker 1: positive ions are going to move to the negatively charged plate. 218 00:13:20,520 --> 00:13:25,920 Speaker 1: Because opposite charges attract. This movement of electrons is electricity. 219 00:13:25,960 --> 00:13:28,720 Speaker 1: That's what electricity is. So it's not a lot of 220 00:13:28,760 --> 00:13:34,400 Speaker 1: electrical current, but it's consistent. Jaeger hypothesized that poison gas 221 00:13:34,480 --> 00:13:38,959 Speaker 1: would interfere with that current of electricity, and that if 222 00:13:38,960 --> 00:13:42,440 Speaker 1: you detected a drop in current, that would set off 223 00:13:42,520 --> 00:13:46,720 Speaker 1: the detector, and Jaeger would say, oh, there's poison gas here. 224 00:13:46,800 --> 00:13:49,480 Speaker 1: So he started testing it, except it didn't work. The 225 00:13:49,520 --> 00:13:52,319 Speaker 1: poison gas did not set off the detector, and as 226 00:13:52,360 --> 00:13:56,680 Speaker 1: the story goes Yaeger was getting frustrated and stressed out 227 00:13:56,760 --> 00:13:59,400 Speaker 1: and he decided to smoke a cigarette and think about 228 00:13:59,480 --> 00:14:02,319 Speaker 1: the problem. And so he lights up the cigarette, he 229 00:14:02,360 --> 00:14:04,360 Speaker 1: starts puffing away and the next thing he knows is 230 00:14:04,440 --> 00:14:07,920 Speaker 1: detector's going off. Now, the poison gas had not interacted 231 00:14:07,960 --> 00:14:12,920 Speaker 1: with the ions, but the smoke did, so what's going on. Well, 232 00:14:13,000 --> 00:14:16,600 Speaker 1: there are particles in smoke that can bond to ions, 233 00:14:16,720 --> 00:14:21,240 Speaker 1: neutralizing them, so negatively charged particles that can bond with 234 00:14:21,280 --> 00:14:24,480 Speaker 1: the positive ones. And when that happens, you get a 235 00:14:24,560 --> 00:14:27,800 Speaker 1: drop in current between those two electric plates I was 236 00:14:27,840 --> 00:14:31,120 Speaker 1: talking about, and that's what sets off the detector. Another 237 00:14:31,160 --> 00:14:35,440 Speaker 1: scientist named Ernst Maley improved upon this design by using 238 00:14:35,480 --> 00:14:39,200 Speaker 1: a cold cathode tube. I've talked about cathode tubes in 239 00:14:39,240 --> 00:14:42,520 Speaker 1: the past. Here's a quick rundown. It's essentially a device 240 00:14:42,560 --> 00:14:45,760 Speaker 1: that emits electrons. Looks a lot like a light bulb. 241 00:14:45,800 --> 00:14:51,200 Speaker 1: You've got a filament that's encased inside a vacuum tube, 242 00:14:51,360 --> 00:14:54,080 Speaker 1: and the ideas that you pass an electric current through 243 00:14:54,120 --> 00:14:57,880 Speaker 1: the cathode tube's filament. The cathode tubes filament heats up 244 00:14:58,000 --> 00:15:01,320 Speaker 1: due to electrical resistance, and as it heats up, it 245 00:15:01,400 --> 00:15:07,520 Speaker 1: starts to emit a stream of electrons due to thermionic emission. Essentially, 246 00:15:08,040 --> 00:15:12,640 Speaker 1: that electrical resistance means that the flow gets impeded. You 247 00:15:12,880 --> 00:15:15,720 Speaker 1: convert some of that energy over into heat. The heat 248 00:15:15,760 --> 00:15:19,600 Speaker 1: itself strips electrons away from the tungsten filament inside, and 249 00:15:19,960 --> 00:15:23,520 Speaker 1: then you get your stream. Cold cathode tubes work on 250 00:15:23,640 --> 00:15:28,000 Speaker 1: a different principle, though they aren't necessarily actually cold. So 251 00:15:28,120 --> 00:15:33,200 Speaker 1: you've got a cathode that's the electrode that would emit electrons, 252 00:15:33,760 --> 00:15:35,880 Speaker 1: and on the opposite end of the tube you have 253 00:15:35,960 --> 00:15:39,520 Speaker 1: an anode that's the side that accepts electrons. So it's 254 00:15:39,520 --> 00:15:44,640 Speaker 1: the positively charged part of this particular device, and these 255 00:15:44,640 --> 00:15:47,800 Speaker 1: are both sealed in a tube, and that tube also 256 00:15:47,880 --> 00:15:51,880 Speaker 1: has a gas inside of it, and applying a sufficient 257 00:15:52,040 --> 00:15:55,480 Speaker 1: voltage between the cathode and the anode a difference in 258 00:15:55,560 --> 00:16:00,000 Speaker 1: electrical charge. If it's sufficient enough, it'll cause a discharge 259 00:16:00,440 --> 00:16:02,520 Speaker 1: between the two and the gas will act as a 260 00:16:02,560 --> 00:16:05,600 Speaker 1: carrier for that electrical current. So a neon light is 261 00:16:05,640 --> 00:16:10,800 Speaker 1: an implementation of the cold cathode tube technology. Melee's objective 262 00:16:11,440 --> 00:16:14,960 Speaker 1: was to boost the signal from the detection circuit so 263 00:16:15,000 --> 00:16:17,640 Speaker 1: that the signal could be strong enough to trigger an alarm, 264 00:16:17,760 --> 00:16:20,880 Speaker 1: So not just that it would detect a drop in 265 00:16:21,320 --> 00:16:24,520 Speaker 1: current or a change in the electrical current across these 266 00:16:24,560 --> 00:16:28,000 Speaker 1: two plates, but that it would also have a strong 267 00:16:28,120 --> 00:16:31,560 Speaker 1: enough signal so it could power a loud speaker or 268 00:16:31,600 --> 00:16:36,800 Speaker 1: activate a physical bell. And a separate circuit in the 269 00:16:36,840 --> 00:16:41,160 Speaker 1: smoke detector activates upon this change in electrical current, sending 270 00:16:41,160 --> 00:16:43,600 Speaker 1: a signal to the cold cathode tube, which acts like 271 00:16:43,640 --> 00:16:47,480 Speaker 1: an amplifier. It takes that incoming signal amplifies it enough 272 00:16:47,480 --> 00:16:49,720 Speaker 1: for it to do some of the useful work like 273 00:16:50,400 --> 00:16:53,680 Speaker 1: powering a loud speaker and thus alerting you that there 274 00:16:53,800 --> 00:16:57,160 Speaker 1: is in fact smoke in the area. Now, Jaeger, being 275 00:16:57,160 --> 00:17:00,400 Speaker 1: an enterprising sort, partnered with Melee to launch a business 276 00:17:00,440 --> 00:17:03,600 Speaker 1: offering smoke detectors in the late nineteen forties. However, these 277 00:17:03,640 --> 00:17:08,720 Speaker 1: detectors weren't terribly practical because they required that high voltage 278 00:17:08,840 --> 00:17:13,200 Speaker 1: to operate to create that ionization chamber, and homes were 279 00:17:13,200 --> 00:17:17,639 Speaker 1: not wired for that kind of high voltage, so that 280 00:17:18,040 --> 00:17:20,720 Speaker 1: meant that you couldn't really get one for your house. 281 00:17:20,760 --> 00:17:24,280 Speaker 1: They were mostly used, again in big industrial settings where 282 00:17:24,320 --> 00:17:27,159 Speaker 1: you could wire things up for that kind of power. 283 00:17:27,680 --> 00:17:30,720 Speaker 1: The solution to this problem was already set in motion, 284 00:17:31,040 --> 00:17:34,160 Speaker 1: though at the time it was top secret. I'll get 285 00:17:34,200 --> 00:17:44,520 Speaker 1: to that after this quick break. Now, while the high 286 00:17:44,640 --> 00:17:48,840 Speaker 1: voltage smoke detectors weren't seen as practical from an implementation 287 00:17:48,960 --> 00:17:52,719 Speaker 1: standpoint for your average homeowner, it was undeniable that they 288 00:17:52,720 --> 00:17:56,000 Speaker 1: were useful, and this was particularly highlighted in the United 289 00:17:56,000 --> 00:17:59,399 Speaker 1: States by a tragedy that took place on December first, 290 00:17:59,520 --> 00:18:02,560 Speaker 1: nineteen f eight, at the Roman Catholic school in Chicago 291 00:18:03,000 --> 00:18:07,360 Speaker 1: called Our Lady of the Angels School. Now, the origins 292 00:18:07,400 --> 00:18:10,400 Speaker 1: of the fire have never been verified. No one knows 293 00:18:10,480 --> 00:18:14,480 Speaker 1: exactly what started it, but it appeared to begin in 294 00:18:14,560 --> 00:18:18,520 Speaker 1: the stairwell for the school, and the school had limited 295 00:18:18,520 --> 00:18:21,760 Speaker 1: fire prevention measures in place. The school itself was an 296 00:18:21,800 --> 00:18:25,880 Speaker 1: older building in Chicago and had been grandfathered into Chicago's 297 00:18:25,960 --> 00:18:30,520 Speaker 1: safety standards because it had previously met earlier regulations. So 298 00:18:30,600 --> 00:18:34,639 Speaker 1: when the city updated its fire safety regulations, one of 299 00:18:34,640 --> 00:18:37,240 Speaker 1: the policies there was that older buildings that had passed 300 00:18:37,280 --> 00:18:42,880 Speaker 1: the previous ones were considered safe. Students and staff were 301 00:18:42,960 --> 00:18:45,680 Speaker 1: unaware of the danger of the fire until it became 302 00:18:45,720 --> 00:18:49,560 Speaker 1: a critical threat, and more than ninety children died in 303 00:18:49,600 --> 00:18:53,199 Speaker 1: that tragedy. It was a truly horrifying event and it 304 00:18:53,280 --> 00:18:57,320 Speaker 1: illustrated the need to develop better fire detection and prevention methods. 305 00:18:58,119 --> 00:19:01,600 Speaker 1: Research in Canada and the United States began looking into 306 00:19:01,720 --> 00:19:06,240 Speaker 1: various catastrophic fires that had happened over the years, and 307 00:19:06,280 --> 00:19:10,000 Speaker 1: according to doctor Jim Milk of the University of Maryland, 308 00:19:10,280 --> 00:19:15,000 Speaker 1: these studies found evidence suggesting that had smoke detectors been 309 00:19:15,040 --> 00:19:18,359 Speaker 1: available at the time, there would have been forty percent 310 00:19:18,480 --> 00:19:23,119 Speaker 1: fewer deaths in those catastrophic fires. There were more than 311 00:19:23,160 --> 00:19:25,600 Speaker 1: three hundred of them that they were looking at, and 312 00:19:26,359 --> 00:19:29,240 Speaker 1: rise of heat detectors, which I'll talk about in a second, 313 00:19:29,359 --> 00:19:33,120 Speaker 1: would have decreased the number of fatalities less than ten percent. 314 00:19:33,880 --> 00:19:36,360 Speaker 1: And these were hypotheses, mind you, there was no way 315 00:19:36,359 --> 00:19:39,199 Speaker 1: of knowing that that in fact would actually have been 316 00:19:39,200 --> 00:19:42,000 Speaker 1: the way it played out. We only know what actually happened, 317 00:19:42,000 --> 00:19:44,960 Speaker 1: not what might have happened. But the scholars were pointing 318 00:19:44,960 --> 00:19:47,439 Speaker 1: out how the cause of death wasn't always due to 319 00:19:47,480 --> 00:19:51,600 Speaker 1: direct exposure to fire itself, which rise of heat detectors 320 00:19:51,600 --> 00:19:54,920 Speaker 1: would help you avoid, but exposure to smoke, and smoke 321 00:19:54,960 --> 00:19:58,320 Speaker 1: detectors might activate well in advance of a rise of 322 00:19:58,359 --> 00:20:01,760 Speaker 1: heat detector, giving people precious time to evacuate a building. 323 00:20:02,480 --> 00:20:05,359 Speaker 1: So that rise of heat detector, that's like the kind 324 00:20:05,359 --> 00:20:07,760 Speaker 1: I was talking about at the top of this episode. 325 00:20:07,880 --> 00:20:12,840 Speaker 1: It's the type that can monitor increases in temperature and 326 00:20:12,960 --> 00:20:16,560 Speaker 1: at a certain temperature they'll activate, they'll sound an alarm, 327 00:20:17,000 --> 00:20:19,119 Speaker 1: but by then it might be too late. So the 328 00:20:19,200 --> 00:20:22,840 Speaker 1: high voltage requirement for smoke detectors that ionized air that 329 00:20:22,960 --> 00:20:26,480 Speaker 1: had an ionization chamber was still a problem at this point. 330 00:20:26,600 --> 00:20:30,119 Speaker 1: It made them impractical and expensive, particularly for homeowners. It 331 00:20:30,280 --> 00:20:33,080 Speaker 1: was again more common for really big buildings like manufacturing 332 00:20:33,119 --> 00:20:36,000 Speaker 1: plants and factories and that kind of thing, and the 333 00:20:36,080 --> 00:20:38,280 Speaker 1: rise of heat detectors like the ones I first described 334 00:20:38,280 --> 00:20:40,480 Speaker 1: in this episode would also be used in those facilities. 335 00:20:40,680 --> 00:20:43,440 Speaker 1: So the solution to this problem of requiring high voltage 336 00:20:43,560 --> 00:20:46,199 Speaker 1: would have its roots in a top secret program that 337 00:20:46,240 --> 00:20:49,720 Speaker 1: had a very different aim. See back in nineteen forty four, 338 00:20:50,080 --> 00:20:52,760 Speaker 1: there was a guy named Glenn Seborg who had been 339 00:20:52,800 --> 00:20:57,359 Speaker 1: asked to join the highly classified Manhattan Project. Now, this was, 340 00:20:57,440 --> 00:21:01,720 Speaker 1: of course, the United States's effort to find a way 341 00:21:01,760 --> 00:21:05,399 Speaker 1: to weaponize atomic energy, to split the atom to release 342 00:21:05,440 --> 00:21:09,199 Speaker 1: an enormous and destructive force that could be used as 343 00:21:09,200 --> 00:21:13,440 Speaker 1: a weapon. Seborg led a team that researched radioactive materials 344 00:21:13,760 --> 00:21:16,080 Speaker 1: as they tried to determine which of them would be 345 00:21:16,119 --> 00:21:19,320 Speaker 1: the most useful in a weapon like an atomic bomb. 346 00:21:19,800 --> 00:21:23,840 Speaker 1: They discovered and created numerous radioactive elements in the process. 347 00:21:24,440 --> 00:21:27,399 Speaker 1: Elements that are above ninety two on the elemental table 348 00:21:27,720 --> 00:21:31,119 Speaker 1: were all synthetic. They were all created in labs and 349 00:21:31,200 --> 00:21:35,320 Speaker 1: their very unstable atoms. Now, among the ones that they 350 00:21:35,320 --> 00:21:40,280 Speaker 1: worked on was one called amerasrium. So ameraserium is a 351 00:21:40,400 --> 00:21:45,760 Speaker 1: synthetic element that was produced in the lab in a 352 00:21:45,800 --> 00:21:50,200 Speaker 1: cyclotron experiment in Berkeley, California. The specific variant that we're 353 00:21:50,240 --> 00:21:53,960 Speaker 1: interested in for this podcast is an isotope of amerasyrium. 354 00:21:54,000 --> 00:21:57,200 Speaker 1: It's ameraserrium two forty one. And you know I mentioned 355 00:21:57,240 --> 00:22:00,760 Speaker 1: what ions are, but what is an isotope case it's 356 00:22:00,760 --> 00:22:03,439 Speaker 1: been a while since you've had basic science because I 357 00:22:03,440 --> 00:22:05,680 Speaker 1: always have to look these up. I'm not trying to 358 00:22:05,680 --> 00:22:08,760 Speaker 1: shame anybody. I get my stuff mixed up, so I 359 00:22:08,760 --> 00:22:10,600 Speaker 1: got to look it up. Well. You know, an ion 360 00:22:10,680 --> 00:22:13,640 Speaker 1: is an atom or molecule that has a net electric charge, right. 361 00:22:13,720 --> 00:22:16,000 Speaker 1: That means it either has too many or too few 362 00:22:16,080 --> 00:22:18,720 Speaker 1: electro electrons for it to balance out with the protons. 363 00:22:19,200 --> 00:22:23,480 Speaker 1: That's an ion. Isotopes are different. You have the right 364 00:22:23,560 --> 00:22:27,040 Speaker 1: number of protons and electrons, but you have different numbers 365 00:22:27,040 --> 00:22:32,400 Speaker 1: of neutrons between two different two or more different variants 366 00:22:32,400 --> 00:22:36,520 Speaker 1: of the same element. So ameraserrium two forty one and 367 00:22:36,560 --> 00:22:40,440 Speaker 1: a marasyrium two forty two are nearly identical. They have 368 00:22:40,480 --> 00:22:42,959 Speaker 1: the same number of protons and the same number of electrons, 369 00:22:43,160 --> 00:22:47,479 Speaker 1: but ameraserrium two forty two has one neutron more than 370 00:22:47,520 --> 00:22:51,560 Speaker 1: a maraserrium two forty one. It changes the atomic mass 371 00:22:52,119 --> 00:22:55,520 Speaker 1: of that particular atom, but otherwise as the same protons 372 00:22:55,520 --> 00:22:59,760 Speaker 1: and electrons as the other isotopes of that element. So 373 00:23:00,000 --> 00:23:03,920 Speaker 1: the maracerrium two forty one is radioactive, which means it 374 00:23:04,080 --> 00:23:08,960 Speaker 1: decays and gives off radiation. It's ionic radiation, so that 375 00:23:09,080 --> 00:23:12,520 Speaker 1: means that the energy that's given off, the radiation that's 376 00:23:12,560 --> 00:23:16,280 Speaker 1: given off is energetic enough to strip electrons off of 377 00:23:16,320 --> 00:23:20,560 Speaker 1: atoms or molecules and ionizing them. A small amount of 378 00:23:20,600 --> 00:23:23,919 Speaker 1: a maraserrium two forty one will ionize atoms like oxygen 379 00:23:23,960 --> 00:23:27,719 Speaker 1: and nitrogen, just through the natural process of radioactive decay. 380 00:23:28,280 --> 00:23:30,560 Speaker 1: So what do I mean by a small amount. I'm 381 00:23:30,560 --> 00:23:34,840 Speaker 1: talking about one five thousandth of a gram, so a 382 00:23:35,080 --> 00:23:41,680 Speaker 1: super tiny amount of radioactive material. Now, smoke detector manufacturers 383 00:23:41,720 --> 00:23:44,879 Speaker 1: did not immediately jump on a maraserium as a replacement 384 00:23:44,960 --> 00:23:48,480 Speaker 1: for a high voltage circuit. That would take some time 385 00:23:48,680 --> 00:23:51,920 Speaker 1: and a lot of study before determining that a maraserrium 386 00:23:52,080 --> 00:23:56,200 Speaker 1: was pretty safe to use under specific parameters. The type 387 00:23:56,240 --> 00:24:00,960 Speaker 1: of radiation gives off is primarily alpha radiation. There's alpha, beta, 388 00:24:01,000 --> 00:24:03,720 Speaker 1: and gamma radiation. I'll talk more about that in a 389 00:24:03,760 --> 00:24:08,560 Speaker 1: subsequent episode, but alpha radiation is the emission of alpha particles, 390 00:24:08,840 --> 00:24:11,560 Speaker 1: and an alpha particle is essentially the same thing as 391 00:24:11,600 --> 00:24:17,040 Speaker 1: a helium nucleus. The nucleus of a helium atom includes 392 00:24:17,080 --> 00:24:20,800 Speaker 1: two protons and two neutrons. That's an alpha particle two 393 00:24:20,800 --> 00:24:25,919 Speaker 1: protons and two neutrons. An alpha particle has good ionization power, 394 00:24:26,480 --> 00:24:29,840 Speaker 1: but it also doesn't have a lot of penetrative power. 395 00:24:29,880 --> 00:24:34,640 Speaker 1: It can't go through matter very easily. It's a massive 396 00:24:34,720 --> 00:24:38,320 Speaker 1: particle in the grand scheme of things and moves more 397 00:24:38,320 --> 00:24:42,040 Speaker 1: slowly than other types of radiation, so an alpha particle 398 00:24:42,119 --> 00:24:44,719 Speaker 1: is too weak to pass through a thin sheet of paper. 399 00:24:45,040 --> 00:24:47,560 Speaker 1: It can only go through a few centimeters of air 400 00:24:48,200 --> 00:24:51,880 Speaker 1: before it loses energy and can't move anymore. So while 401 00:24:51,880 --> 00:24:56,280 Speaker 1: ameras serium two forty one is radioactive, it's considered relatively 402 00:24:56,440 --> 00:25:00,359 Speaker 1: safe in small amounts and if kept in isolation. You 403 00:25:00,400 --> 00:25:03,120 Speaker 1: wouldn't want to come into direct contact with the stuff, 404 00:25:03,400 --> 00:25:06,760 Speaker 1: and you definitely wouldn't want to inhale or ingest any 405 00:25:06,840 --> 00:25:10,639 Speaker 1: mrror serium or get it in an open wound because 406 00:25:10,680 --> 00:25:14,840 Speaker 1: it is carcinogenic. But it would have to get past barriers. 407 00:25:15,240 --> 00:25:17,760 Speaker 1: It's not even strong enough to get through the skin, 408 00:25:18,359 --> 00:25:20,520 Speaker 1: but it is strong enough if you were to ingest 409 00:25:20,600 --> 00:25:24,800 Speaker 1: it or breathe in some dust, it could potentially cause cancer. 410 00:25:24,880 --> 00:25:28,760 Speaker 1: It could certainly increase your risk of developing cancer, so 411 00:25:29,400 --> 00:25:32,000 Speaker 1: there is a danger to it. So your typical smoke 412 00:25:32,080 --> 00:25:36,320 Speaker 1: detector actually has some radioactive material in it to create 413 00:25:36,359 --> 00:25:40,200 Speaker 1: the ions that flow between two charged plates. The ions 414 00:25:40,240 --> 00:25:43,919 Speaker 1: behave just as the ones did with Jaeger's high voltage device. 415 00:25:43,960 --> 00:25:47,080 Speaker 1: It's the same sort of stuff. It's charged particles, So 416 00:25:47,160 --> 00:25:49,439 Speaker 1: smoke particles will still interact with them, just as they 417 00:25:49,440 --> 00:25:53,720 Speaker 1: would with Jaeger's invention with the high voltage grid, and 418 00:25:53,760 --> 00:25:56,480 Speaker 1: they will still bind and cause a drop in current, 419 00:25:56,560 --> 00:25:59,399 Speaker 1: and that's what triggers the circuit that powers the actual alarm. 420 00:26:00,160 --> 00:26:04,320 Speaker 1: It would be nearly two decades between the invention of 421 00:26:04,359 --> 00:26:08,000 Speaker 1: a maraserium to forty one and its application as an 422 00:26:08,000 --> 00:26:11,680 Speaker 1: ion generator in a smoke detector. The United States Atomic 423 00:26:11,840 --> 00:26:16,080 Speaker 1: Energy Commission would grant a license in nineteen sixty three 424 00:26:16,400 --> 00:26:19,840 Speaker 1: authorizing the use of a maraserium to forty one in 425 00:26:20,160 --> 00:26:22,720 Speaker 1: smoke detectors. And the thought was that the amount of 426 00:26:22,760 --> 00:26:28,840 Speaker 1: radioactive material would be so tiny that it would not 427 00:26:28,960 --> 00:26:31,840 Speaker 1: really stand to be a hazard, and it was just 428 00:26:31,880 --> 00:26:34,720 Speaker 1: a very low risk, but there was a very real 429 00:26:34,880 --> 00:26:39,680 Speaker 1: risk of fire and smoke, and so when you weigh 430 00:26:39,720 --> 00:26:42,720 Speaker 1: it against each other and said, the risk of fire 431 00:26:42,840 --> 00:26:45,600 Speaker 1: is high, and the risk of something happening because of 432 00:26:45,640 --> 00:26:48,760 Speaker 1: this very tiny amount of radioactive material is low. It 433 00:26:48,800 --> 00:26:51,480 Speaker 1: makes way more sense to err on the side of 434 00:26:51,920 --> 00:26:55,800 Speaker 1: detecting fires. So two years later, in nineteen sixty five, 435 00:26:56,359 --> 00:27:00,920 Speaker 1: a guy named Dwayne D. Persall introduced a battery powered 436 00:27:01,119 --> 00:27:05,400 Speaker 1: smoke detector. This eliminated the need for that high voltage circuit, 437 00:27:05,760 --> 00:27:09,240 Speaker 1: and Percell came by this accidentally. A lot of inventions 438 00:27:09,480 --> 00:27:12,080 Speaker 1: really ended up being created as a consequence of some 439 00:27:12,200 --> 00:27:15,680 Speaker 1: other unrelated effort. So in nineteen sixty three, that same 440 00:27:15,720 --> 00:27:19,959 Speaker 1: year where the Atomic Energy Commission granted the license, Percell 441 00:27:20,080 --> 00:27:24,040 Speaker 1: had been working on some tough problems with his employees. 442 00:27:24,280 --> 00:27:26,840 Speaker 1: Not problems with his employees, but with his employees. They 443 00:27:26,840 --> 00:27:29,720 Speaker 1: were working on tough problems. Purcell was in a rough spot, 444 00:27:29,800 --> 00:27:31,600 Speaker 1: so he had taken out a second mortgage on his 445 00:27:31,640 --> 00:27:34,399 Speaker 1: house to create a company called Persol Company and a 446 00:27:34,440 --> 00:27:39,280 Speaker 1: spinoff company called Satratol or Sata Troll rather Sata Trill 447 00:27:39,600 --> 00:27:44,840 Speaker 1: Corporation in Denver, Colorado. I find that name incredibly difficult 448 00:27:44,880 --> 00:27:47,480 Speaker 1: to say properly. In fact, I'm sure I'm saying it incorrectly. 449 00:27:47,520 --> 00:27:51,359 Speaker 1: But anyway, The company's main business was selling heating and 450 00:27:51,440 --> 00:27:54,960 Speaker 1: air distribution equipment for commercial buildings, so sort of like 451 00:27:55,000 --> 00:27:59,040 Speaker 1: an HVAC company for big, big, big buildings. But the 452 00:27:59,080 --> 00:28:02,600 Speaker 1: product is engineered were working on was what he called 453 00:28:02,680 --> 00:28:05,919 Speaker 1: a static neutralizer. The idea was he was going to 454 00:28:05,960 --> 00:28:08,720 Speaker 1: create an ion generator, and the idea was that these 455 00:28:08,760 --> 00:28:13,959 Speaker 1: ions would neutralize static electricity build up on equipment, and 456 00:28:14,000 --> 00:28:16,679 Speaker 1: that's something that could be a real issue for industrial 457 00:28:16,720 --> 00:28:19,840 Speaker 1: operations and clean rooms and stuff. So you need to 458 00:28:19,880 --> 00:28:22,400 Speaker 1: have a way to neutralize static build up or else 459 00:28:22,440 --> 00:28:26,560 Speaker 1: you can have a discharge that could ruin tons of work. However, 460 00:28:26,800 --> 00:28:29,800 Speaker 1: his team had encountered a problem. They saw that their 461 00:28:29,840 --> 00:28:33,720 Speaker 1: ion generator was getting clogged up pretty quickly. The ions 462 00:28:33,720 --> 00:28:37,959 Speaker 1: were attracting particles like dust and stuff, and as it 463 00:28:38,000 --> 00:28:41,560 Speaker 1: was attracting dust, it was starting to make the entire 464 00:28:41,600 --> 00:28:45,040 Speaker 1: device as a whole less effective. An engineer named Lyman 465 00:28:45,120 --> 00:28:48,040 Speaker 1: Blackwell was running tests to see what could be done 466 00:28:48,080 --> 00:28:52,440 Speaker 1: to keep the ion generation going. While testing the system, 467 00:28:52,840 --> 00:28:55,360 Speaker 1: they noticed that the ion meter they were using to 468 00:28:55,440 --> 00:28:59,360 Speaker 1: monitor performance would occasionally fluctuate, and one of the technicians 469 00:28:59,440 --> 00:29:03,560 Speaker 1: running the equipment was a smoker. He was chained smoking 470 00:29:03,680 --> 00:29:06,360 Speaker 1: during the whole testing process. Eventually they figured out that 471 00:29:06,360 --> 00:29:10,360 Speaker 1: the meter was detecting fluctuations in the ion flow whenever 472 00:29:10,680 --> 00:29:13,959 Speaker 1: smoke was getting pulled in through the fan on the 473 00:29:14,000 --> 00:29:18,320 Speaker 1: generator and inserted into the ion stream. So essentially they 474 00:29:18,320 --> 00:29:22,080 Speaker 1: were making the same discovery that Jaeger had made decades earlier. 475 00:29:22,560 --> 00:29:26,560 Speaker 1: But the big difference was that Percell's ion generator didn't 476 00:29:26,600 --> 00:29:29,240 Speaker 1: require that high voltage to run because it was depending 477 00:29:29,280 --> 00:29:32,360 Speaker 1: on that small amount of amerserium two forty one. So 478 00:29:32,600 --> 00:29:35,400 Speaker 1: he had the bright idea to take this unexpected result 479 00:29:35,440 --> 00:29:38,600 Speaker 1: and turn it into an actual product. Two years later, 480 00:29:38,840 --> 00:29:42,920 Speaker 1: he had the first battery operated, ionization based smoke detector. 481 00:29:43,120 --> 00:29:46,120 Speaker 1: He called it the Smoke Guard seven hundred, but it 482 00:29:46,160 --> 00:29:49,120 Speaker 1: wasn't quite ready for the home market yet because government 483 00:29:49,160 --> 00:29:52,760 Speaker 1: regulations had not yet caught up to the technology. We're 484 00:29:52,760 --> 00:29:54,360 Speaker 1: going to get into that as well, because, as it 485 00:29:54,400 --> 00:29:56,880 Speaker 1: turns out, it's not enough just to make tech that works. 486 00:29:57,320 --> 00:29:59,800 Speaker 1: You have to make tech that works within the boundaries 487 00:29:59,800 --> 00:30:04,920 Speaker 1: of laws and regulations. Meanwhile, a pair of inventors named 488 00:30:05,040 --> 00:30:08,960 Speaker 1: Donald Steel and Robert Emmerk came up with an alternative 489 00:30:09,120 --> 00:30:13,760 Speaker 1: method for detecting smoke with a device and this approach 490 00:30:13,760 --> 00:30:17,720 Speaker 1: wouldn't used ionized particles at all, so there's no need 491 00:30:17,760 --> 00:30:22,080 Speaker 1: to create any sort of ionization chamber. Instead, Steel and 492 00:30:22,200 --> 00:30:26,360 Speaker 1: Emark created a smoke detector that relied upon light and 493 00:30:26,440 --> 00:30:31,000 Speaker 1: photo detectors. So photo detectors. Those are that's light sensors, right, 494 00:30:31,080 --> 00:30:34,520 Speaker 1: so sensor that detects light. They are two basic categories 495 00:30:34,560 --> 00:30:38,240 Speaker 1: of light sensors. The first type are sometimes called photovoltaics. 496 00:30:38,560 --> 00:30:42,800 Speaker 1: These are devices that emit electrons when they're exposed to light, 497 00:30:43,040 --> 00:30:48,040 Speaker 1: so solar panels are a type of photovoltaic cells. They 498 00:30:48,440 --> 00:30:52,200 Speaker 1: generate electricity when exposed to light. The other type of 499 00:30:52,320 --> 00:30:56,000 Speaker 1: light sensor would be the photo resistor or photoconductor. These 500 00:30:56,040 --> 00:31:00,400 Speaker 1: sensors have electrical properties that change if they are actually 501 00:31:00,440 --> 00:31:04,440 Speaker 1: exposed to light. So, for example, a photo resistor has 502 00:31:04,480 --> 00:31:08,080 Speaker 1: a relatively high electrical resistance when it's in the dark, 503 00:31:08,480 --> 00:31:13,200 Speaker 1: so that material resists the flow of electricity going through it. However, 504 00:31:13,440 --> 00:31:17,120 Speaker 1: as the material is exposed to light, the electrical resistance 505 00:31:17,320 --> 00:31:21,160 Speaker 1: decreases and electricity can pass through it more readily. So 506 00:31:21,400 --> 00:31:23,480 Speaker 1: if you place one of these devices in a circuit 507 00:31:23,880 --> 00:31:27,280 Speaker 1: and you have a voltage detector also attached to that circuit. 508 00:31:27,640 --> 00:31:30,720 Speaker 1: The detector will pick up changes in voltage as light 509 00:31:30,880 --> 00:31:36,120 Speaker 1: hits the sensor. Now, you could try and build a 510 00:31:36,240 --> 00:31:39,760 Speaker 1: smoke detector that works by having a light shining on 511 00:31:39,800 --> 00:31:43,480 Speaker 1: a photosensor of some sort that's at least partially open 512 00:31:43,520 --> 00:31:46,480 Speaker 1: to the air outside of the detector, and if something 513 00:31:46,560 --> 00:31:51,320 Speaker 1: like smoke were to enter that pathway the direct detector's vents, 514 00:31:51,360 --> 00:31:54,320 Speaker 1: and it somehow gets in between the light and the sensor, 515 00:31:55,120 --> 00:31:59,400 Speaker 1: then you would have smoke obscuring or blocking some of 516 00:31:59,440 --> 00:32:02,200 Speaker 1: that light, and if it were enough, then the alarm 517 00:32:02,240 --> 00:32:04,720 Speaker 1: would go off. But that actually wouldn't be a very 518 00:32:04,800 --> 00:32:07,960 Speaker 1: sensitive smoke detector. It wouldn't work unless the smoke was 519 00:32:07,960 --> 00:32:10,880 Speaker 1: thick enough to really cause an issue. It's actually pretty 520 00:32:10,880 --> 00:32:15,240 Speaker 1: tricky for a sensor to detect dips in light intensity, 521 00:32:15,800 --> 00:32:18,200 Speaker 1: and by the time it would the smoke might be 522 00:32:18,240 --> 00:32:20,760 Speaker 1: thick enough to already be a major threat to people's safety. 523 00:32:21,080 --> 00:32:23,720 Speaker 1: But there's a clever workaround to this. So instead of 524 00:32:23,720 --> 00:32:26,680 Speaker 1: an alarm that goes off when a light no longer 525 00:32:26,800 --> 00:32:30,600 Speaker 1: is shining on, it, design a system where the alarm 526 00:32:30,640 --> 00:32:34,240 Speaker 1: goes off if the sensor detects light. Even a small 527 00:32:34,240 --> 00:32:37,760 Speaker 1: amount of light can create enough of a signal for 528 00:32:37,840 --> 00:32:41,560 Speaker 1: it to send a message to start the alarm. So 529 00:32:41,600 --> 00:32:44,520 Speaker 1: in this version, you've got a light that's shining down 530 00:32:44,640 --> 00:32:47,840 Speaker 1: a pathway. So imagine a chamber. You got a light 531 00:32:47,880 --> 00:32:52,440 Speaker 1: at one end, and it's open so that air can 532 00:32:52,520 --> 00:32:56,240 Speaker 1: come into the chamber at a nine degree angle, like 533 00:32:56,280 --> 00:32:59,520 Speaker 1: a perpendicular angle to this light, and tucked away just 534 00:32:59,560 --> 00:33:02,840 Speaker 1: a bit, you have a little alcove where there's a sensor. 535 00:33:03,120 --> 00:33:06,400 Speaker 1: So under normal conditions, the light is going through the chamber, 536 00:33:06,640 --> 00:33:09,320 Speaker 1: but the sensor is tucked in at a right angle, 537 00:33:09,680 --> 00:33:11,960 Speaker 1: so it's not picking up any light. The sensor stays 538 00:33:12,000 --> 00:33:16,880 Speaker 1: in the dark. However, if smoke enters the chamber that 539 00:33:16,960 --> 00:33:19,760 Speaker 1: the light is passing through, some of that light hits 540 00:33:19,800 --> 00:33:23,040 Speaker 1: the smoke and starts to scatter. And this is the 541 00:33:23,040 --> 00:33:24,920 Speaker 1: same sort of effect you would see if you were 542 00:33:25,040 --> 00:33:28,320 Speaker 1: driving a car on a really foggy day. It's why 543 00:33:28,320 --> 00:33:30,440 Speaker 1: you're not supposed to use the high beams on your 544 00:33:30,440 --> 00:33:32,840 Speaker 1: head lights when you're in the fog. The light will 545 00:33:32,920 --> 00:33:35,320 Speaker 1: hit the fog and scatter, and it's more likely to 546 00:33:35,320 --> 00:33:38,880 Speaker 1: make it harder for you to see rather than easier. Well, 547 00:33:38,880 --> 00:33:42,320 Speaker 1: on the smoke detector, some of that scattered light hits 548 00:33:42,400 --> 00:33:45,360 Speaker 1: the sensor, which then activates a signal to the alarm, 549 00:33:45,880 --> 00:33:49,480 Speaker 1: and that approach allows for far more sensitivity in a 550 00:33:49,520 --> 00:33:53,400 Speaker 1: smoke detector. They can go off much faster than one 551 00:33:53,440 --> 00:33:56,920 Speaker 1: that would require the smoke to block the light. So 552 00:33:57,000 --> 00:33:59,240 Speaker 1: a dark sensor picking up on light is just more 553 00:33:59,280 --> 00:34:02,640 Speaker 1: reliable than a lit up since they're trying to detect 554 00:34:02,680 --> 00:34:06,440 Speaker 1: a dip in brightness. However, it's also not fool proof 555 00:34:06,480 --> 00:34:10,959 Speaker 1: because vapor or dust could cause false alarms. Now, during 556 00:34:11,000 --> 00:34:14,560 Speaker 1: all this innovation, changes were starting to happen on regulatory 557 00:34:14,640 --> 00:34:16,960 Speaker 1: levels around the world, and when we come back, I'll 558 00:34:16,960 --> 00:34:19,440 Speaker 1: talk more about how that played out in the United States. 559 00:34:19,440 --> 00:34:29,560 Speaker 1: But first let's take another quick break. All right, So 560 00:34:29,600 --> 00:34:33,120 Speaker 1: now we've got the basic technology of smoke detectors understood, 561 00:34:33,200 --> 00:34:36,440 Speaker 1: let's talk about regulations. See, if you're going to produce 562 00:34:36,600 --> 00:34:40,800 Speaker 1: and market something that's meant to protect lives, it's often 563 00:34:40,800 --> 00:34:44,200 Speaker 1: the case that a government agency or two will take 564 00:34:44,280 --> 00:34:46,919 Speaker 1: notice and they want to make sure that the thing 565 00:34:47,000 --> 00:34:51,240 Speaker 1: you're making does what you claim it does. If lives 566 00:34:51,320 --> 00:34:54,040 Speaker 1: literally hang in the balance, it's important. So this is 567 00:34:54,080 --> 00:34:57,759 Speaker 1: the same basic underlying philosophy we see in agencies that 568 00:34:57,840 --> 00:35:02,960 Speaker 1: monitor stuff like food processing, pharmaceutical development and production. The 569 00:35:03,000 --> 00:35:06,120 Speaker 1: era I'm talking about in the late nineteen sixties in 570 00:35:06,160 --> 00:35:10,080 Speaker 1: the United States was a particularly tumultuous time. You had 571 00:35:10,120 --> 00:35:13,560 Speaker 1: the civil rights movement, you had America's involvement in Vietnam, 572 00:35:14,000 --> 00:35:18,320 Speaker 1: and other really politically charged events playing out in the US. 573 00:35:18,760 --> 00:35:23,160 Speaker 1: And these were sparks pun intended that ignited civil unrest 574 00:35:23,200 --> 00:35:27,480 Speaker 1: across the entire country, and in turn that was testing 575 00:35:27,520 --> 00:35:31,920 Speaker 1: the limits of police forces and fire prevention and fire 576 00:35:33,719 --> 00:35:40,120 Speaker 1: extinguishing services. So this prompted the US Congress to re 577 00:35:40,239 --> 00:35:45,319 Speaker 1: examine policies around safety to better protect citizens. One thing 578 00:35:45,360 --> 00:35:47,960 Speaker 1: to come out of this was the Fire Research and 579 00:35:48,080 --> 00:35:51,080 Speaker 1: Safety Act, which was signed into law by then President 580 00:35:51,239 --> 00:35:55,360 Speaker 1: Lyndon Johnson. The President was citing some figures that suggested 581 00:35:55,360 --> 00:35:58,920 Speaker 1: as many as twelve thousand Americans had died in fires 582 00:35:59,000 --> 00:36:04,160 Speaker 1: in nineteen sixty. Later estimates adjusted that number down significantly 583 00:36:04,200 --> 00:36:06,920 Speaker 1: to like eight thousand, but that's still way too many people. 584 00:36:07,600 --> 00:36:10,600 Speaker 1: The Act called for the creation of a twenty person 585 00:36:10,800 --> 00:36:15,040 Speaker 1: panel to study the challenges and make recommendations for new 586 00:36:15,120 --> 00:36:18,360 Speaker 1: safety standards that could be carried out at the federal 587 00:36:18,480 --> 00:36:22,520 Speaker 1: level and require any building in the US to follow 588 00:36:22,640 --> 00:36:25,760 Speaker 1: certain processes to make sure that they were safe for people, 589 00:36:26,239 --> 00:36:27,840 Speaker 1: and it took a few years for all of this 590 00:36:27,960 --> 00:36:30,880 Speaker 1: to actually coalesce into a report. I mean, it was 591 00:36:31,160 --> 00:36:34,839 Speaker 1: a big task, and we also happen to know that 592 00:36:35,160 --> 00:36:39,040 Speaker 1: things in the US government don't go super fast. But 593 00:36:39,120 --> 00:36:43,000 Speaker 1: in nineteen seventy three, the panel released a report. The 594 00:36:43,080 --> 00:36:47,839 Speaker 1: report was titled America Burning, which is pretty sobering all 595 00:36:47,880 --> 00:36:51,319 Speaker 1: on its own. And America was leading the way in 596 00:36:51,320 --> 00:36:54,759 Speaker 1: industrial nations when it came to per capita deaths and 597 00:36:54,800 --> 00:36:59,239 Speaker 1: property loss due to fire. So the argument they were 598 00:36:59,239 --> 00:37:02,719 Speaker 1: making was that America is this incredibly advanced country, Why 599 00:37:02,760 --> 00:37:05,040 Speaker 1: the heck are we losing so much to fire? We 600 00:37:05,080 --> 00:37:07,880 Speaker 1: should be doing better than that, And eighty percent of 601 00:37:07,920 --> 00:37:12,480 Speaker 1: the deaths were occurring in people's homes. The report also 602 00:37:12,560 --> 00:37:17,719 Speaker 1: contained pictures of Percell's smoke Guard detector. He had come 603 00:37:17,760 --> 00:37:22,040 Speaker 1: to overcome challenges to make his detectors practical and safe. Now. 604 00:37:22,040 --> 00:37:25,719 Speaker 1: His original design did not have a battery. Instead, it 605 00:37:25,760 --> 00:37:28,800 Speaker 1: was to be hardwired into the electrical system of a building. 606 00:37:29,560 --> 00:37:31,960 Speaker 1: It didn't require two hundred and twenty volts like the 607 00:37:32,080 --> 00:37:35,600 Speaker 1: earlier smoke detectors off Switzerland did, but it still was 608 00:37:35,640 --> 00:37:39,320 Speaker 1: an expensive proposition, and it made it an unlikely candidate 609 00:37:39,400 --> 00:37:42,680 Speaker 1: for home adoption because every unit would set someone back 610 00:37:42,719 --> 00:37:45,440 Speaker 1: about one thousand dollars at the time, which would be 611 00:37:45,520 --> 00:37:48,680 Speaker 1: a lot more than that today. So his team was 612 00:37:48,719 --> 00:37:51,440 Speaker 1: able to create a version that would operate on battery power, 613 00:37:51,680 --> 00:37:54,120 Speaker 1: which was already an engineering triumph. But they need to 614 00:37:54,120 --> 00:37:57,960 Speaker 1: figure out how to make this a reliable one, or 615 00:37:58,000 --> 00:38:01,600 Speaker 1: to convince people that it was reliable, because batteries, as 616 00:38:01,600 --> 00:38:06,040 Speaker 1: we all know, eventually exhaust themselves. The chemical reactions inside 617 00:38:06,040 --> 00:38:10,759 Speaker 1: a battery are what produces electrons, and over time, you 618 00:38:10,800 --> 00:38:12,719 Speaker 1: get to a point where there's been enough of the 619 00:38:12,800 --> 00:38:15,720 Speaker 1: chemical reaction going on that you don't have the active 620 00:38:15,840 --> 00:38:21,719 Speaker 1: ingredients necessary to sustain that supply of electricity anymore, and 621 00:38:21,760 --> 00:38:24,719 Speaker 1: not the proper voltage anyway. And we're talking about something 622 00:38:24,719 --> 00:38:27,440 Speaker 1: as critical as a smoke detector, that's a real problem. 623 00:38:27,760 --> 00:38:31,520 Speaker 1: So his team solved this issue by creating circuits that 624 00:38:31,600 --> 00:38:36,240 Speaker 1: would send a chirping alarm to the smoke detector if 625 00:38:36,320 --> 00:38:39,720 Speaker 1: it detected a drop in voltage across the primary circuit 626 00:38:39,800 --> 00:38:42,600 Speaker 1: of the smoke detector. So the chirp wouldn't require very 627 00:38:42,640 --> 00:38:46,120 Speaker 1: much energy of itself, and it would be repeated until 628 00:38:46,200 --> 00:38:49,120 Speaker 1: the voltage across the circuit returned to the proper level, 629 00:38:49,160 --> 00:38:52,200 Speaker 1: in other words, until the battery was replaced. In addition, 630 00:38:52,560 --> 00:38:56,279 Speaker 1: Percell included a small card in the box for the 631 00:38:56,280 --> 00:38:59,439 Speaker 1: smoke Guard seven hundred, and customers were meant to take 632 00:38:59,480 --> 00:39:02,759 Speaker 1: the card and then fill out little forms on the 633 00:39:02,800 --> 00:39:06,279 Speaker 1: card with their own information, including their address and the 634 00:39:06,360 --> 00:39:10,200 Speaker 1: date that they installed their smoke detector, and Personal's company 635 00:39:10,200 --> 00:39:14,080 Speaker 1: would actually mail out an annual reminder to its customers saying, hey, 636 00:39:14,200 --> 00:39:16,000 Speaker 1: it's time for you to replace the battery and your 637 00:39:16,040 --> 00:39:19,520 Speaker 1: smoke detector. In order to keep it operational, Personal worked 638 00:39:19,640 --> 00:39:24,080 Speaker 1: closely with safety officials and organizations both to improve his 639 00:39:24,200 --> 00:39:27,840 Speaker 1: smoke detectors and make them more useful, and also to 640 00:39:27,920 --> 00:39:31,880 Speaker 1: help shape policy so that these detectors would be recognized 641 00:39:31,920 --> 00:39:34,239 Speaker 1: as effective and a good option to help curb the 642 00:39:34,280 --> 00:39:38,279 Speaker 1: problem of fatalities due to fire disasters, and the work 643 00:39:38,280 --> 00:39:40,800 Speaker 1: paid off both for Personal and for people in general. 644 00:39:40,840 --> 00:39:43,720 Speaker 1: He was able to convince officials that a battery powered 645 00:39:43,760 --> 00:39:47,759 Speaker 1: smoke detector was effective if it had the ability to 646 00:39:47,800 --> 00:39:51,359 Speaker 1: alert occupants of a dying battery. The government actually would 647 00:39:51,400 --> 00:39:55,480 Speaker 1: mandate that the chirping alarm sound should last at least 648 00:39:55,640 --> 00:39:59,520 Speaker 1: seven consecutive days in an effort to alert homeowners to 649 00:39:59,640 --> 00:40:02,880 Speaker 1: change battery. And this was specifically in case someone might 650 00:40:02,920 --> 00:40:05,279 Speaker 1: be out of town when the battery starts to give out. 651 00:40:05,719 --> 00:40:08,160 Speaker 1: They wanted it to last long enough so that you 652 00:40:08,200 --> 00:40:10,800 Speaker 1: would have time to get back and find out, oh, gosh, 653 00:40:10,840 --> 00:40:13,080 Speaker 1: I need to switch out the batteries on my smoke detector. 654 00:40:13,480 --> 00:40:15,640 Speaker 1: The government also had to balance out the cost of 655 00:40:15,640 --> 00:40:21,640 Speaker 1: installing fire prevention systems and homes, including in newly constructed homes. Initially, 656 00:40:21,680 --> 00:40:26,680 Speaker 1: plans called for both smoke detectors and rise of heat detectors. However, 657 00:40:27,120 --> 00:40:30,560 Speaker 1: after numerous studies, the government concluded that rise of heat 658 00:40:30,560 --> 00:40:33,799 Speaker 1: detectors weren't really practical if you were looking at trying 659 00:40:33,840 --> 00:40:37,560 Speaker 1: to save lives. They just weren't good enough to do that, 660 00:40:38,120 --> 00:40:41,919 Speaker 1: and they were really expensive, and that smoke detectors were 661 00:40:42,040 --> 00:40:46,279 Speaker 1: much better for the purpose of preventing fatalities. And so 662 00:40:46,320 --> 00:40:48,319 Speaker 1: that meant that they got rid of the rise of 663 00:40:48,360 --> 00:40:52,680 Speaker 1: heat detector requirement, and that helped bring the cost down 664 00:40:52,840 --> 00:40:56,200 Speaker 1: of implementing fire protection systems and homes, and that in 665 00:40:56,239 --> 00:40:59,040 Speaker 1: turn increased the likelihood that people would actually follow the 666 00:40:59,120 --> 00:41:03,200 Speaker 1: rules and adopt smoke detectors. The regulations paved the way 667 00:41:03,239 --> 00:41:06,400 Speaker 1: for Personal to manufacture, market, and sell his smoke detectors 668 00:41:06,440 --> 00:41:09,040 Speaker 1: to the American public, who could be reassured that the 669 00:41:09,040 --> 00:41:12,680 Speaker 1: devices would actually provide a valuable and potentially life saving service. 670 00:41:13,120 --> 00:41:16,280 Speaker 1: He scaled up his company to meet demand before eventually 671 00:41:16,360 --> 00:41:19,520 Speaker 1: selling it off in nineteen seventy seven. And from everything 672 00:41:19,560 --> 00:41:22,040 Speaker 1: I've read about him, it sounds like he was motivated 673 00:41:22,040 --> 00:41:26,000 Speaker 1: not only by an entrepreneurial spirit, although he certainly had that, 674 00:41:26,640 --> 00:41:29,200 Speaker 1: but also a genuine desire to make his community and 675 00:41:29,239 --> 00:41:32,400 Speaker 1: the world a better place if he could. And I 676 00:41:32,400 --> 00:41:35,800 Speaker 1: think that's pretty cool. Since the introduction of the optical 677 00:41:35,840 --> 00:41:40,879 Speaker 1: and the ionization chamber based smoke detectors, we've seen some innovations, 678 00:41:40,960 --> 00:41:44,359 Speaker 1: but the basic principles all remain the same. There are 679 00:41:44,400 --> 00:41:48,640 Speaker 1: smoke detectors that incorporate both types of methodologies, meaning there 680 00:41:48,640 --> 00:41:52,080 Speaker 1: are smoke detectors that have independent systems to detect the 681 00:41:52,120 --> 00:41:55,880 Speaker 1: presence of smoke, and we've seen some incorporate other types 682 00:41:55,920 --> 00:41:58,200 Speaker 1: of tech, such as network connectivity in the form of 683 00:41:58,239 --> 00:42:02,319 Speaker 1: products like the Nest Protect smoke detector, and those smoke 684 00:42:02,400 --> 00:42:05,720 Speaker 1: detectors add a little more functionality to the basic kind. 685 00:42:06,000 --> 00:42:08,719 Speaker 1: They work on basically the same principle, but they have 686 00:42:08,800 --> 00:42:13,680 Speaker 1: some more features. For example, they can send information across 687 00:42:13,719 --> 00:42:17,000 Speaker 1: a local area network wirelessly and then that network can 688 00:42:17,040 --> 00:42:20,480 Speaker 1: send an alert to you on an app on a smartphone, 689 00:42:20,560 --> 00:42:22,719 Speaker 1: and that could be valuable if, for example, you're away 690 00:42:22,719 --> 00:42:25,200 Speaker 1: from your home when an alarm goes off. To give 691 00:42:25,200 --> 00:42:29,680 Speaker 1: you a notification, you can perhaps either call home, or 692 00:42:29,680 --> 00:42:31,600 Speaker 1: if no one's home, you might even call a fire 693 00:42:31,640 --> 00:42:33,960 Speaker 1: department to go and check on your home to make 694 00:42:34,000 --> 00:42:37,279 Speaker 1: sure that everything is all right. And most homes have 695 00:42:37,440 --> 00:42:39,919 Speaker 1: multiple smoke detectors. In fact, you're supposed to have one 696 00:42:39,960 --> 00:42:43,080 Speaker 1: outside of every bedroom, for example, as well as maybe 697 00:42:43,200 --> 00:42:46,080 Speaker 1: one in the kitchen. My own home has six of 698 00:42:46,080 --> 00:42:49,480 Speaker 1: the darn things, and it can be an issue of 699 00:42:49,480 --> 00:42:52,959 Speaker 1: figuring out which detector is going off, and that could 700 00:42:52,960 --> 00:42:58,239 Speaker 1: be of vital importance. So with connected detectors, then you 701 00:42:58,280 --> 00:43:01,719 Speaker 1: get a notification saying toctor number three is going off, 702 00:43:02,000 --> 00:43:04,880 Speaker 1: and you know that number three happens to be outside 703 00:43:04,920 --> 00:43:08,160 Speaker 1: the guest room, so you would be able to very 704 00:43:08,239 --> 00:43:11,759 Speaker 1: quickly figure out what's going on, as opposed to trying 705 00:43:11,800 --> 00:43:14,879 Speaker 1: to determine which of your numerous alarms is going off. 706 00:43:15,880 --> 00:43:18,200 Speaker 1: It also means that if a battery is running out 707 00:43:18,280 --> 00:43:21,920 Speaker 1: and a smoke detector is chirping, or maybe a battery 708 00:43:22,040 --> 00:43:24,600 Speaker 1: was just a bad battery and starts to chirp, you 709 00:43:24,640 --> 00:43:27,840 Speaker 1: can more quickly track down which detector is making the 710 00:43:27,920 --> 00:43:32,200 Speaker 1: chirping noise. This really applies to folks like me because 711 00:43:32,239 --> 00:43:35,080 Speaker 1: I live in a townhouse that has a few floors, 712 00:43:35,440 --> 00:43:38,040 Speaker 1: and the center of the townhouse is essentially like a chimney. 713 00:43:38,280 --> 00:43:41,279 Speaker 1: There are stairs that go from the bottom floor, and 714 00:43:42,600 --> 00:43:44,719 Speaker 1: the stairwells open all the way to the top of 715 00:43:44,800 --> 00:43:49,760 Speaker 1: the townhouse, so it's like an echo chamber inside my house, 716 00:43:50,280 --> 00:43:52,880 Speaker 1: which means when something like a smoke detector starts to chirp, 717 00:43:53,080 --> 00:43:55,920 Speaker 1: I can't easily identify whether it's on the floor I'm 718 00:43:55,960 --> 00:43:58,840 Speaker 1: on the floor above me or the floor below me. 719 00:43:59,200 --> 00:44:02,759 Speaker 1: And I have six smoke detectors. If it's time to 720 00:44:02,840 --> 00:44:05,600 Speaker 1: replace the batteries, that's one thing, But if it's just 721 00:44:05,640 --> 00:44:09,040 Speaker 1: that a battery is going bad early, then I have 722 00:44:09,080 --> 00:44:12,320 Speaker 1: to figure out which of those detectors is making the problem. 723 00:44:12,480 --> 00:44:16,400 Speaker 1: And exacerbating this issue for me is the fact that 724 00:44:16,400 --> 00:44:19,239 Speaker 1: I have a cute little doggie named tibult and the 725 00:44:19,400 --> 00:44:24,360 Speaker 1: chirping smoke detector noise causes him intense distress, like he 726 00:44:24,440 --> 00:44:29,720 Speaker 1: starts to shake with fear. So I get really upset 727 00:44:29,840 --> 00:44:33,280 Speaker 1: when one of my smoke detectors starts to chirp prematurely. 728 00:44:33,440 --> 00:44:36,120 Speaker 1: There's no smoke or anything. It's just giving me a 729 00:44:36,200 --> 00:44:40,000 Speaker 1: chirp alarm. But that's a me problem. One other thing 730 00:44:40,040 --> 00:44:42,160 Speaker 1: that a lot of smoke detectors can do these days 731 00:44:42,640 --> 00:44:47,799 Speaker 1: is they can also perform as carbon monoxide detectors. So 732 00:44:47,840 --> 00:44:52,120 Speaker 1: carbon monoxide is an odorless and colorless gas, so human 733 00:44:52,120 --> 00:44:56,359 Speaker 1: beings can't easily detect it, and it's also toxic. It's 734 00:44:56,360 --> 00:45:00,280 Speaker 1: a byproduct from burning carbon based fuels like gasoline, heating oil, 735 00:45:00,360 --> 00:45:04,200 Speaker 1: or natural gas, and in confined spaces it can be 736 00:45:04,239 --> 00:45:07,759 Speaker 1: really dangerous stuff, so like a garage, for example. And 737 00:45:07,840 --> 00:45:11,120 Speaker 1: while we humans can't really detect carbon monoxide with our 738 00:45:11,160 --> 00:45:13,640 Speaker 1: own senses, there are a lot of other ways to 739 00:45:13,719 --> 00:45:17,160 Speaker 1: see if the stuff is around. So carbon monoxide detectors 740 00:45:17,200 --> 00:45:20,800 Speaker 1: can work using one of a few different methods. Upon detection, 741 00:45:20,880 --> 00:45:23,160 Speaker 1: they basically do the same thing as a smoke detector. 742 00:45:23,200 --> 00:45:25,600 Speaker 1: They send a signal to sound an alarm, but the 743 00:45:25,640 --> 00:45:29,360 Speaker 1: way they detect the carbon monoxide can be a little different. 744 00:45:30,200 --> 00:45:34,760 Speaker 1: So there are three basic approaches to this, and one 745 00:45:34,840 --> 00:45:39,600 Speaker 1: you might have what are called biomimetic sensors. These sensors 746 00:45:39,920 --> 00:45:44,319 Speaker 1: mimic us the name some sort of biological function, such 747 00:45:44,360 --> 00:45:49,400 Speaker 1: as hemoglobin, which interacts with carbon monoxide. So these sensors 748 00:45:49,800 --> 00:45:52,759 Speaker 1: have a gel inside of them, and that gel can 749 00:45:52,840 --> 00:45:57,480 Speaker 1: absorb carbon monoxide. As the gel does absorb carbon monoxide, 750 00:45:57,520 --> 00:46:02,760 Speaker 1: the gel changes color. Separate sensor that's monitoring the color 751 00:46:02,880 --> 00:46:06,400 Speaker 1: of the gel, and if the gel changes, then the 752 00:46:06,440 --> 00:46:09,360 Speaker 1: sensor picks up on that change and sends a signal 753 00:46:09,360 --> 00:46:13,200 Speaker 1: to the alarm. These sensors can actually be reset. The 754 00:46:13,239 --> 00:46:18,640 Speaker 1: gel will return to its original color once it gets 755 00:46:18,719 --> 00:46:20,879 Speaker 1: rid of that carbon monoxide, but it has to be 756 00:46:20,920 --> 00:46:23,480 Speaker 1: set in an environment that's free of carbon monoxide for 757 00:46:23,520 --> 00:46:27,279 Speaker 1: several hours in order to reset. The next type is 758 00:46:27,320 --> 00:46:31,239 Speaker 1: the metal oxide semiconductor sensor. This has components that have 759 00:46:31,280 --> 00:46:34,080 Speaker 1: a certain level of electrical resistance, very much like the 760 00:46:34,120 --> 00:46:37,880 Speaker 1: optical smoke detectors I talked about earlier. So these components 761 00:46:38,120 --> 00:46:41,359 Speaker 1: react with carbon monoxide in a way that lowers the 762 00:46:41,400 --> 00:46:45,960 Speaker 1: material's electrical resistance and so meters are monitoring a voltage 763 00:46:46,000 --> 00:46:49,960 Speaker 1: across a circuit, and if it detects this change in voltage, 764 00:46:50,239 --> 00:46:55,319 Speaker 1: then it will send a signal to the alarm. And 765 00:46:55,360 --> 00:46:58,040 Speaker 1: the third type of sensor that you could find in 766 00:46:58,080 --> 00:47:02,640 Speaker 1: a carbon monoxide detector as an electrochemical sensor. These sensors 767 00:47:02,680 --> 00:47:06,120 Speaker 1: also detect changes an electrical current in the presence of 768 00:47:06,160 --> 00:47:10,319 Speaker 1: carbon monoxide, but they have electrodes that are inside a 769 00:47:10,400 --> 00:47:14,360 Speaker 1: chemical solution, so they're actually engulfed in a chemical solution. 770 00:47:14,520 --> 00:47:17,960 Speaker 1: Around these electrodes and the chemicals in the solution react 771 00:47:18,120 --> 00:47:21,400 Speaker 1: very very quickly in the presence of carbon monoxide, and 772 00:47:21,440 --> 00:47:26,920 Speaker 1: that changes the electrical qualities of the solution, which means 773 00:47:27,239 --> 00:47:29,920 Speaker 1: that you are able to detect a change in the 774 00:47:29,960 --> 00:47:33,800 Speaker 1: circuit very very quickly. In fact, this stuff is used 775 00:47:33,840 --> 00:47:38,640 Speaker 1: in professional settings. It's a very sensitive kind of alarm. Today, 776 00:47:38,680 --> 00:47:40,560 Speaker 1: there are a lots of smoke detectors that double as 777 00:47:40,600 --> 00:47:45,560 Speaker 1: carbon monoxide detectors with separate components monitoring the environment. I 778 00:47:45,640 --> 00:47:48,600 Speaker 1: hope you enjoyed that episode from February tenth, twenty twenty, 779 00:47:48,600 --> 00:47:51,560 Speaker 1: how smoke detectors work. As a reminder, I will be 780 00:47:51,680 --> 00:47:54,560 Speaker 1: back next week with all new episodes. I have no 781 00:47:54,640 --> 00:47:57,440 Speaker 1: idea what they'll be about because currently I'm on space 782 00:47:57,480 --> 00:48:00,279 Speaker 1: mountain or something. I hope you're all well, and I'll 783 00:48:00,280 --> 00:48:08,360 Speaker 1: talk to you again really soon. Tech Stuff is a 784 00:48:08,360 --> 00:48:12,720 Speaker 1: production of iHeartRadio's House Stuff Works. For more podcasts from iHeartRadio, 785 00:48:13,040 --> 00:48:16,759 Speaker 1: visit the iHeartRadio app, Apple Podcasts, or wherever you listen 786 00:48:16,800 --> 00:48:17,840 Speaker 1: to your favorite shows.