1 00:00:04,240 --> 00:00:07,240 Speaker 1: Welcome to tex Stuff, a production of I Heart Radios 2 00:00:07,320 --> 00:00:14,280 Speaker 1: How Stuff Works. Hey there, and welcome to tex Stuff. 3 00:00:14,320 --> 00:00:17,599 Speaker 1: I'm your host, Jonathan Strickland. I'm an executive producer with 4 00:00:17,680 --> 00:00:19,919 Speaker 1: I Heart Radio and a love of all things tech. 5 00:00:20,560 --> 00:00:22,919 Speaker 1: And you know, recently guys that did episodes about how 6 00:00:23,000 --> 00:00:26,760 Speaker 1: matches work and how lighters work and talked about how 7 00:00:27,040 --> 00:00:31,320 Speaker 1: chemists and physicists and inventors were able to make it 8 00:00:31,360 --> 00:00:33,920 Speaker 1: easier than ever to light a fire. So I thought 9 00:00:34,080 --> 00:00:36,640 Speaker 1: it's really only fitting if I do an episode about 10 00:00:36,760 --> 00:00:40,159 Speaker 1: smoke detectors and smoke alarms and and other types of 11 00:00:40,400 --> 00:00:46,239 Speaker 1: fire alarms to talk about their history and how they work. Now, clearly, 12 00:00:46,680 --> 00:00:51,080 Speaker 1: smoke detectors are incredibly important because we all know fires 13 00:00:51,120 --> 00:00:54,319 Speaker 1: can be life threatening. They can spread quickly, they can 14 00:00:54,360 --> 00:00:57,000 Speaker 1: cut off potential escape routes for the people who are 15 00:00:57,000 --> 00:00:59,880 Speaker 1: caught in the way. So early warning systems that can 16 00:01:00,000 --> 00:01:03,640 Speaker 1: alert us to danger before it becomes a mortal danger 17 00:01:03,760 --> 00:01:07,759 Speaker 1: are fantastic inventions. And there are a couple of inventions 18 00:01:07,760 --> 00:01:10,240 Speaker 1: I want to talk about before we actually get to 19 00:01:10,360 --> 00:01:13,440 Speaker 1: smoke detectors. I'm sure that doesn't come as a surprise 20 00:01:13,480 --> 00:01:15,640 Speaker 1: to any of you who have listened to tech stuff 21 00:01:15,640 --> 00:01:18,720 Speaker 1: episodes before, I always like to set the ground. Well, 22 00:01:18,800 --> 00:01:20,760 Speaker 1: the first one that I want to talk about is 23 00:01:20,760 --> 00:01:24,920 Speaker 1: the portable electric fire alarm, as in a fire alarm 24 00:01:25,000 --> 00:01:28,120 Speaker 1: that works on electricity, not a fire alarm that detects 25 00:01:28,160 --> 00:01:32,440 Speaker 1: electric fires. Francis Robbins Upton, who was a physicist who 26 00:01:32,480 --> 00:01:36,240 Speaker 1: was a partner and general manager of the Edison lamp works, 27 00:01:36,520 --> 00:01:40,520 Speaker 1: you know as in Thomas Edison, developed this particular invention 28 00:01:40,600 --> 00:01:45,080 Speaker 1: back in eight Now. According to the patent, the design 29 00:01:45,120 --> 00:01:49,200 Speaker 1: would sound an alarm after detecting that the temperature had 30 00:01:49,320 --> 00:01:53,920 Speaker 1: risen above some predetermined limit, so if it got too hot, 31 00:01:54,440 --> 00:01:57,280 Speaker 1: this thing would go off. And the way this would 32 00:01:57,320 --> 00:02:00,520 Speaker 1: work was really clever. You can actually learn exactly how 33 00:02:00,520 --> 00:02:03,560 Speaker 1: it was supposed to work based on the patent that 34 00:02:03,920 --> 00:02:08,960 Speaker 1: Upton got on this particular invention. So the way it 35 00:02:09,000 --> 00:02:11,600 Speaker 1: works is that the there are a pair of electrical 36 00:02:11,680 --> 00:02:15,360 Speaker 1: contacts and if they are in in contact with each other, 37 00:02:15,400 --> 00:02:18,400 Speaker 1: if they touch each other, it completes a circuit. But 38 00:02:18,560 --> 00:02:22,400 Speaker 1: normally there's a gap between them. An electricity can't pass 39 00:02:22,520 --> 00:02:26,239 Speaker 1: between the two that it can't cross that gap, so 40 00:02:26,400 --> 00:02:29,839 Speaker 1: it's normally in the off position. However, one of those 41 00:02:29,880 --> 00:02:34,960 Speaker 1: two electrical contacts is mounted on a fixed arm and 42 00:02:35,000 --> 00:02:37,720 Speaker 1: the other is on an arm that's attached to a 43 00:02:37,800 --> 00:02:43,640 Speaker 1: coil of bimetallic material. Now, I mentioned bimetallic strips in 44 00:02:43,680 --> 00:02:46,520 Speaker 1: the episode about lighters, and it's something you find in 45 00:02:46,600 --> 00:02:50,920 Speaker 1: a lot of different technologies that depend upon changes in 46 00:02:51,000 --> 00:02:56,560 Speaker 1: temperature as a variable, like thermostats have bimetallic strips in them. 47 00:02:56,880 --> 00:02:59,320 Speaker 1: And essentially what it is is a strip of metal 48 00:02:59,600 --> 00:03:03,480 Speaker 1: that insists of two different metals. And think of it 49 00:03:03,520 --> 00:03:06,200 Speaker 1: as like a metal sandwich, a top side and a 50 00:03:06,240 --> 00:03:09,760 Speaker 1: bottom side, and one metal is the top side, the 51 00:03:09,840 --> 00:03:12,920 Speaker 1: other metal is the bottom side, and each metal has 52 00:03:12,919 --> 00:03:16,359 Speaker 1: slightly different properties, and one of those properties is how 53 00:03:16,480 --> 00:03:19,960 Speaker 1: quickly they expand when they're heated up. You know, we 54 00:03:20,040 --> 00:03:22,880 Speaker 1: know that metal expands as it gets warmer. While using 55 00:03:22,880 --> 00:03:25,959 Speaker 1: a bimetallic strip, you have one side that will expand 56 00:03:26,080 --> 00:03:29,680 Speaker 1: faster than the other side, and when that happens, it 57 00:03:29,720 --> 00:03:34,240 Speaker 1: causes the strip to curl, so it deforms as it 58 00:03:34,280 --> 00:03:38,200 Speaker 1: gets warmer, one side is expanding faster than the other 59 00:03:38,720 --> 00:03:42,000 Speaker 1: and you get this curled metal as a result. So 60 00:03:42,080 --> 00:03:46,600 Speaker 1: with Upton's proposed invention in the patent, this coil of 61 00:03:46,640 --> 00:03:50,520 Speaker 1: bimetallic material would act as sort of an actuator. As 62 00:03:50,520 --> 00:03:53,840 Speaker 1: it would get warm, it would expand and this in 63 00:03:53,880 --> 00:03:57,800 Speaker 1: turn would create a pushing force on the arm with 64 00:03:57,960 --> 00:04:01,280 Speaker 1: the electrical contact on it that then can move toward 65 00:04:01,480 --> 00:04:04,840 Speaker 1: the other electrical contact that's in a fixed position. And 66 00:04:04,920 --> 00:04:09,080 Speaker 1: so once the coil had expanded enough, the two contacts 67 00:04:09,080 --> 00:04:12,760 Speaker 1: would touch one another and it would complete a circuit. 68 00:04:13,200 --> 00:04:16,800 Speaker 1: At that point, electrical current could actually flow from a 69 00:04:16,839 --> 00:04:20,000 Speaker 1: battery that was connected to this device all the way 70 00:04:20,040 --> 00:04:24,000 Speaker 1: through to activate an alarm bell. So once the temperature 71 00:04:24,040 --> 00:04:27,400 Speaker 1: got hot enough the two contacts touch, you get a circuit. 72 00:04:27,760 --> 00:04:30,120 Speaker 1: The alarm bell goes off. If it cools down, the 73 00:04:30,160 --> 00:04:34,560 Speaker 1: contacts will slowly separate, and eventually they'll separate enough where 74 00:04:34,560 --> 00:04:38,120 Speaker 1: that electrical circuit can't be complete anymore. The alarm bell 75 00:04:38,160 --> 00:04:41,640 Speaker 1: would go off. And Upton's invention was, without a doubt, 76 00:04:41,760 --> 00:04:45,479 Speaker 1: a very clever one, and it could help save property 77 00:04:45,680 --> 00:04:48,839 Speaker 1: by sounding an alarm before a fire had raged completely 78 00:04:48,839 --> 00:04:53,599 Speaker 1: out of control. But there are many dangers with fires, 79 00:04:53,880 --> 00:04:57,480 Speaker 1: and heat is just one of them. Another very serious 80 00:04:57,560 --> 00:05:00,960 Speaker 1: danger is smoke, which not only a scares your vision, 81 00:05:01,360 --> 00:05:04,720 Speaker 1: but it also can suffocate you as well. So while 82 00:05:04,720 --> 00:05:08,800 Speaker 1: the alarm as design would work, it wouldn't necessarily be 83 00:05:08,960 --> 00:05:13,560 Speaker 1: enough to save lives, or it might not save enough lives, 84 00:05:13,600 --> 00:05:16,120 Speaker 1: because it would only go into action after the temperature 85 00:05:16,160 --> 00:05:20,200 Speaker 1: had already increased enough to make this bimetallic strip expand 86 00:05:20,200 --> 00:05:23,720 Speaker 1: to a sufficient degree, and by that time it might 87 00:05:23,760 --> 00:05:27,080 Speaker 1: already be too late for the people in that building. Now, 88 00:05:27,080 --> 00:05:30,640 Speaker 1: as far as I know, Edison's company didn't actually produce 89 00:05:30,800 --> 00:05:33,400 Speaker 1: any of these fire alarms, but they did patent it. 90 00:05:33,960 --> 00:05:36,640 Speaker 1: Over in Great Britain, there was a fellow named George 91 00:05:36,680 --> 00:05:40,799 Speaker 1: Andrew Darby who patented his own fire alarm, also triggered 92 00:05:40,880 --> 00:05:44,719 Speaker 1: by an increase in temperature. But Darby's invention did not 93 00:05:45,000 --> 00:05:50,840 Speaker 1: depend upon bimetallic strips. It depended on butter for some 94 00:05:50,880 --> 00:05:55,880 Speaker 1: other material that melts at higher temperatures. Say what, all right, 95 00:05:56,000 --> 00:06:00,120 Speaker 1: So imagine you've got a see saw like contraption, a 96 00:06:00,240 --> 00:06:03,039 Speaker 1: lever in other words, and the heavy end of the 97 00:06:03,120 --> 00:06:07,680 Speaker 1: lever uh is up in the air actually because you 98 00:06:07,720 --> 00:06:10,320 Speaker 1: have a weight on the opposite end of that lever. 99 00:06:10,440 --> 00:06:12,520 Speaker 1: So it's like a kid sitting on a seesaw that 100 00:06:12,560 --> 00:06:15,080 Speaker 1: doesn't have another kid at the end of it. The 101 00:06:15,160 --> 00:06:17,440 Speaker 1: kid at the end of the seesaw weighs it down 102 00:06:17,800 --> 00:06:20,359 Speaker 1: and the free end of the seesaws up in the 103 00:06:20,400 --> 00:06:24,560 Speaker 1: air well in this case, the fire alarms seesaw. The 104 00:06:24,839 --> 00:06:27,240 Speaker 1: arm that's up in the air has an electrical contact 105 00:06:27,240 --> 00:06:30,560 Speaker 1: point on it, and if the arm of the seesaw 106 00:06:30,600 --> 00:06:34,679 Speaker 1: were to come down, that contact would complete a circuit, 107 00:06:35,200 --> 00:06:38,800 Speaker 1: and thus electricity would be able to run from a 108 00:06:38,800 --> 00:06:43,719 Speaker 1: battery through an alarm, very much like Upton's invention. So 109 00:06:43,800 --> 00:06:45,840 Speaker 1: weighing down the other end of the arm, the thing 110 00:06:45,880 --> 00:06:48,640 Speaker 1: that's actually keeping the electrical contact up in the air 111 00:06:49,360 --> 00:06:53,039 Speaker 1: is a block of butter or fat or wax or 112 00:06:53,120 --> 00:06:57,080 Speaker 1: some other material that can melt at higher temperatures. So 113 00:06:57,160 --> 00:07:00,720 Speaker 1: as the temperature rises, the block begins to melt away, 114 00:07:01,080 --> 00:07:04,320 Speaker 1: and eventually it melts enough so that the weight isn't 115 00:07:04,320 --> 00:07:06,760 Speaker 1: sufficient to keep the other end of the seesaw up 116 00:07:06,760 --> 00:07:09,560 Speaker 1: in the air, and it'll sink down and the contact 117 00:07:09,640 --> 00:07:12,120 Speaker 1: will complete the circuit and the alarm will go off. 118 00:07:12,640 --> 00:07:16,480 Speaker 1: I was amused to find a butter based fire alarm. 119 00:07:16,600 --> 00:07:18,680 Speaker 1: I wasn't surprised that it came out of England, but 120 00:07:18,760 --> 00:07:20,720 Speaker 1: I was amused to find it. I can think of 121 00:07:20,720 --> 00:07:24,280 Speaker 1: a few potential problems with such an arrangement. For example, 122 00:07:24,600 --> 00:07:28,720 Speaker 1: it might start attracting pests that could eat the weight. 123 00:07:29,320 --> 00:07:32,040 Speaker 1: So in those cases you wouldn't actually have a fire alarm, 124 00:07:32,320 --> 00:07:35,640 Speaker 1: but you might have a rat alarm, or it would 125 00:07:35,680 --> 00:07:40,120 Speaker 1: just turn rancid and smell awful. It's still a pretty 126 00:07:40,120 --> 00:07:42,880 Speaker 1: clever approach, but not one that I think you would 127 00:07:42,880 --> 00:07:46,880 Speaker 1: actually want to put in your buildings. But these solutions 128 00:07:47,240 --> 00:07:50,679 Speaker 1: weren't practical for homes or anything like that. As I mentioned, 129 00:07:50,760 --> 00:07:52,960 Speaker 1: they wouldn't really alert you to the presence of smoke, 130 00:07:53,200 --> 00:07:55,120 Speaker 1: which on its own would be enough to be deadly. 131 00:07:55,600 --> 00:07:58,440 Speaker 1: So this was really looked at as more of a 132 00:07:58,480 --> 00:08:02,560 Speaker 1: solution for things like factories facilities, where you've got a 133 00:08:02,560 --> 00:08:05,800 Speaker 1: lot of industrial operations going on, where the risk of 134 00:08:05,840 --> 00:08:09,000 Speaker 1: fire is high and the risk of property loss is 135 00:08:09,080 --> 00:08:15,160 Speaker 1: also high. Smoke detectors also trace their history back to chemists, physicists, 136 00:08:15,200 --> 00:08:18,040 Speaker 1: and inventors, and in fact, you could say that smoke 137 00:08:18,080 --> 00:08:22,080 Speaker 1: detectors were made possible not just through exploratory science, but 138 00:08:22,200 --> 00:08:26,280 Speaker 1: also happy accidents. And will begin with a super smart 139 00:08:26,520 --> 00:08:30,280 Speaker 1: Swiss physicist in the early twentieth century and try saying 140 00:08:30,320 --> 00:08:35,720 Speaker 1: that three times fast super smart Swiss physicist. His name 141 00:08:36,200 --> 00:08:41,280 Speaker 1: was Heinrich Grinaker and Grindeker or grind Acre if you prefer, 142 00:08:41,679 --> 00:08:46,760 Speaker 1: studied a lot of different stuff, including radioactivity. Vilhelm Rindken 143 00:08:46,800 --> 00:08:51,920 Speaker 1: had discovered the existence of X rays in and Grindeker 144 00:08:52,080 --> 00:08:54,440 Speaker 1: devoted a good deal of his work toward getting a 145 00:08:54,520 --> 00:08:59,000 Speaker 1: better understanding of X rays and other forms of radiation, 146 00:08:59,040 --> 00:09:02,560 Speaker 1: and to do that he had to overcome some practical obstacles. 147 00:09:02,679 --> 00:09:05,480 Speaker 1: For example, he needed a device to help measure the 148 00:09:05,520 --> 00:09:08,680 Speaker 1: intensity of X rays, and such a device didn't really 149 00:09:08,720 --> 00:09:12,160 Speaker 1: exist yet, so he got to work inventing one. X 150 00:09:12,240 --> 00:09:16,160 Speaker 1: rays are a type of ionizing radiation that means that 151 00:09:16,200 --> 00:09:20,800 Speaker 1: when they encounter molecules or atoms, they can ionize them. 152 00:09:21,120 --> 00:09:23,960 Speaker 1: And an ion is a molecule or an atom that 153 00:09:24,000 --> 00:09:27,599 Speaker 1: has a net electrical charge, So it's either a positive 154 00:09:28,320 --> 00:09:32,120 Speaker 1: particle or a negative particle. And a positive ion is 155 00:09:32,160 --> 00:09:35,520 Speaker 1: one that has more protons than electrons, so you have 156 00:09:35,559 --> 00:09:38,240 Speaker 1: a net positive charge. A negative ion would be the opposite, 157 00:09:38,320 --> 00:09:42,480 Speaker 1: has more electrons than protons and has a net negative charge. Now, 158 00:09:42,480 --> 00:09:47,199 Speaker 1: one thing Grineker did was to create ions by building 159 00:09:47,280 --> 00:09:50,640 Speaker 1: a grid of wires through which he could stream high 160 00:09:50,760 --> 00:09:55,520 Speaker 1: voltage current and you would pass air molecules essentially through 161 00:09:55,600 --> 00:10:01,040 Speaker 1: this grid, and the current would strip electron off of 162 00:10:01,040 --> 00:10:05,520 Speaker 1: those particles, creating positive ions. So the grid was in 163 00:10:05,559 --> 00:10:08,880 Speaker 1: this chamber through which gas could move, and as I said, 164 00:10:08,880 --> 00:10:11,560 Speaker 1: the current would ionize the gas. But the other really 165 00:10:11,600 --> 00:10:15,079 Speaker 1: neat thing he did was he invented a voltage multiplier 166 00:10:15,240 --> 00:10:18,920 Speaker 1: circuit because he needed to generate this really high voltage 167 00:10:19,559 --> 00:10:23,760 Speaker 1: around two twenty volts actually, and that could take incoming 168 00:10:23,800 --> 00:10:28,960 Speaker 1: alternating current electricity. That's the type of electricity that power 169 00:10:29,040 --> 00:10:31,880 Speaker 1: plants typically send out because it's easier to send out 170 00:10:32,000 --> 00:10:37,199 Speaker 1: alternating current over long distances than direct current. Well, Grindaker's 171 00:10:37,200 --> 00:10:40,720 Speaker 1: invention would bring in alternating current and then convert it 172 00:10:40,720 --> 00:10:43,520 Speaker 1: to direct current and run the direct current through a 173 00:10:43,559 --> 00:10:46,640 Speaker 1: circuit with stuff like capacitors and diodes. And the whole 174 00:10:46,640 --> 00:10:50,520 Speaker 1: process is a bit complicated to explain, particularly without the 175 00:10:50,600 --> 00:10:54,200 Speaker 1: use of visual aids, and also it goes beyond today's topic. 176 00:10:54,480 --> 00:10:56,480 Speaker 1: But the future I will have to talk about voltage 177 00:10:56,520 --> 00:11:00,240 Speaker 1: multiplying circuits more specifically, because they are in and in 178 00:11:00,280 --> 00:11:03,959 Speaker 1: all sorts of technologies, including super cool bleeding edge science 179 00:11:03,960 --> 00:11:07,199 Speaker 1: stuff like particle accelerators. But for the purposes of this episode, 180 00:11:07,200 --> 00:11:09,320 Speaker 1: The important thing to remember is that it made it 181 00:11:09,360 --> 00:11:14,160 Speaker 1: possible for Grindeker to create an ionization chamber. Now, Greennecker's 182 00:11:14,280 --> 00:11:18,280 Speaker 1: concern was radioactivity, and so we're gonna leave off his 183 00:11:18,360 --> 00:11:20,760 Speaker 1: part of the story at this point because that was 184 00:11:20,800 --> 00:11:24,800 Speaker 1: his big contribution, was creating a feasible way to make 185 00:11:24,800 --> 00:11:28,040 Speaker 1: an ionization chamber. We need to focus more on the 186 00:11:28,040 --> 00:11:31,640 Speaker 1: folks who actually made the first smoke detectors. Uh. Maybe 187 00:11:31,679 --> 00:11:34,320 Speaker 1: I'll do a full episode about Grienneker and other early 188 00:11:34,400 --> 00:11:36,920 Speaker 1: physicists in the future, since their work would lead to 189 00:11:36,960 --> 00:11:41,160 Speaker 1: a deeper understanding of atomic physics and by extension, quantum physics. 190 00:11:41,160 --> 00:11:43,560 Speaker 1: But for now, we're going to get back to smoke alarms. 191 00:11:43,640 --> 00:11:47,400 Speaker 1: So that brings us to our next Swiss smarty pants person, 192 00:11:47,880 --> 00:11:52,920 Speaker 1: Valter Yeager. Now, back in n Yeager wasn't setting out 193 00:11:52,960 --> 00:11:56,440 Speaker 1: to build a smoke detector. That wasn't his goal. Instead, 194 00:11:56,520 --> 00:12:00,560 Speaker 1: he had developed a hypothesis. He thought that perhaps using 195 00:12:00,559 --> 00:12:03,480 Speaker 1: a device with an ionization chamber like the one grind 196 00:12:03,520 --> 00:12:07,559 Speaker 1: Acre had made, he could build a poison gas detector. 197 00:12:08,000 --> 00:12:10,000 Speaker 1: So how did he think he could do this? Well, 198 00:12:10,000 --> 00:12:12,760 Speaker 1: this gets into how smoke detectors actually work. So we're 199 00:12:12,760 --> 00:12:15,680 Speaker 1: going to dive into it. All right, So, as I 200 00:12:15,720 --> 00:12:18,760 Speaker 1: said before, you've got your ionized particles. That's a basic 201 00:12:18,800 --> 00:12:22,200 Speaker 1: component of a large number of smoke detectors. There's actually 202 00:12:22,240 --> 00:12:25,040 Speaker 1: a different type of smoke detector that doesn't use an 203 00:12:25,040 --> 00:12:28,040 Speaker 1: ionization chamber at all, but i'll cover that later in 204 00:12:28,040 --> 00:12:32,280 Speaker 1: this episode. So, these ionized particles are positively charged. They've 205 00:12:32,280 --> 00:12:34,720 Speaker 1: had electrons stripped off of them, so they have more 206 00:12:34,720 --> 00:12:39,680 Speaker 1: protons than electrons. They're positively charged. A battery connected to 207 00:12:39,760 --> 00:12:43,920 Speaker 1: two metal plates creates a positively charged surface on one 208 00:12:44,000 --> 00:12:47,240 Speaker 1: side and a negatively charged surface on the other side. 209 00:12:47,640 --> 00:12:52,679 Speaker 1: So the electrons that are stripped away from the molecules 210 00:12:53,000 --> 00:12:56,720 Speaker 1: will then move to the positively charged plate and the 211 00:12:56,800 --> 00:12:59,760 Speaker 1: positive ions are going to move to the negatively charged plate. 212 00:12:59,800 --> 00:13:05,280 Speaker 1: But has opposite charges attract this movement of electrons is electricity. 213 00:13:05,320 --> 00:13:08,040 Speaker 1: That's what electricity is. So it's not a lot of 214 00:13:08,080 --> 00:13:13,800 Speaker 1: electrical current, but it's consistent. Yeager hypothesized that poison gas 215 00:13:13,800 --> 00:13:18,280 Speaker 1: would interfere with that current of electricity, and that if 216 00:13:18,280 --> 00:13:21,800 Speaker 1: you detected a drop in current, that would set off 217 00:13:21,840 --> 00:13:26,040 Speaker 1: the detector, and Yeager would say, oh, there's poison gas here. 218 00:13:26,120 --> 00:13:28,840 Speaker 1: So he started testing it accept it didn't work. The 219 00:13:28,840 --> 00:13:31,680 Speaker 1: poison gas did not set off the detector. And as 220 00:13:31,720 --> 00:13:36,000 Speaker 1: the story goes, Yeager was getting frustrated and stressed out 221 00:13:36,120 --> 00:13:38,800 Speaker 1: and he decided to smoke a cigarette and think about 222 00:13:38,840 --> 00:13:41,640 Speaker 1: the problem. And so he lights up the cigarette. He 223 00:13:41,679 --> 00:13:43,680 Speaker 1: starts puffing away, and the next thing he knows is 224 00:13:43,720 --> 00:13:47,240 Speaker 1: detectors going off. Now, the poison gas had not interacted 225 00:13:47,280 --> 00:13:52,280 Speaker 1: with the ions, but the smoke did, So what's going on. Well, 226 00:13:52,320 --> 00:13:55,800 Speaker 1: there are particles in smoke that can bond to ions, 227 00:13:56,040 --> 00:14:00,600 Speaker 1: neutralizing them, So negatively charged particles that can bond with 228 00:14:00,640 --> 00:14:03,800 Speaker 1: the positive ones. And when that happens, you get a 229 00:14:03,880 --> 00:14:07,120 Speaker 1: drop in current between those two electric plates I was 230 00:14:07,160 --> 00:14:10,440 Speaker 1: talking about, and that's what sets off the detector. Another 231 00:14:10,480 --> 00:14:14,760 Speaker 1: scientist named Ernst Maine improved upon this design by using 232 00:14:14,800 --> 00:14:18,560 Speaker 1: a cold cathode tube. I've talked about cathode tubes in 233 00:14:18,559 --> 00:14:21,840 Speaker 1: the past. Here's a quick rundown. It's essentially a device 234 00:14:21,920 --> 00:14:25,360 Speaker 1: that emits electrons. Looks a lot like a lightbulb. You've 235 00:14:25,400 --> 00:14:30,480 Speaker 1: got a a filament that's encased inside a vacuum tube, 236 00:14:30,720 --> 00:14:33,400 Speaker 1: and the ideas that you pass an electric current through 237 00:14:33,440 --> 00:14:37,200 Speaker 1: the cathode tubes filament the cathode tubes filament heats up 238 00:14:37,280 --> 00:14:40,640 Speaker 1: due to electrical resistance, and as it heats up, it 239 00:14:40,720 --> 00:14:46,840 Speaker 1: starts to emit a stream of electrons due to thermionic emission. Essentially, 240 00:14:47,360 --> 00:14:51,960 Speaker 1: that electrical resistance means that the flow gets impeded. You 241 00:14:52,160 --> 00:14:55,080 Speaker 1: convert some of that energy over into heat. The heat 242 00:14:55,120 --> 00:14:59,120 Speaker 1: itself strips electrons away from the tungusten filament inside, and 243 00:14:59,280 --> 00:15:02,880 Speaker 1: then you get your dream. Cold cathode tubes work on 244 00:15:02,960 --> 00:15:07,360 Speaker 1: a different principle, though they aren't necessarily actually cold. So 245 00:15:07,480 --> 00:15:12,520 Speaker 1: you've got a cathode that's the electrode that would emit electrons, 246 00:15:13,120 --> 00:15:15,200 Speaker 1: and on the opposite end of the tube you have 247 00:15:15,280 --> 00:15:18,880 Speaker 1: an anode that's the side that accepts electron. So it's 248 00:15:18,880 --> 00:15:23,960 Speaker 1: the positively charged part of this particular device. And these 249 00:15:24,000 --> 00:15:27,080 Speaker 1: are both sealed in a tube, and that tube also 250 00:15:27,200 --> 00:15:31,239 Speaker 1: has a gas inside of it, and applying a sufficient 251 00:15:31,360 --> 00:15:34,800 Speaker 1: voltage between the cathode and the anode a difference in 252 00:15:34,880 --> 00:15:38,760 Speaker 1: electrical charge. If it's sufficient enough, it will cause a 253 00:15:38,840 --> 00:15:41,720 Speaker 1: discharge between the two and the gas will act as 254 00:15:41,720 --> 00:15:44,720 Speaker 1: a carrier for that electrical current. So a neon light 255 00:15:44,880 --> 00:15:49,560 Speaker 1: is an implementation of the cold cathode tube technology. Malee's 256 00:15:49,600 --> 00:15:53,680 Speaker 1: objective was to boost the signal from the detection circuit 257 00:15:54,120 --> 00:15:56,360 Speaker 1: so that the signal could be strong enough to trigger 258 00:15:56,400 --> 00:15:59,880 Speaker 1: an alarm, so not just that would detect a drop 259 00:16:00,160 --> 00:16:03,680 Speaker 1: in current or a change in the electrical current across 260 00:16:03,720 --> 00:16:06,840 Speaker 1: these two plates, but that it would also have a 261 00:16:06,960 --> 00:16:10,880 Speaker 1: strong enough signal so it could power allowed speaker or 262 00:16:10,920 --> 00:16:16,120 Speaker 1: activate a physical bell. And a separate circuit in the 263 00:16:16,160 --> 00:16:20,480 Speaker 1: smoke detector activates upon this change in electrical current, sending 264 00:16:20,480 --> 00:16:22,920 Speaker 1: a signal to the cold cathode tube, which acts like 265 00:16:22,960 --> 00:16:26,800 Speaker 1: an amplifier. It takes that incoming signal amplifies it enough 266 00:16:26,840 --> 00:16:29,080 Speaker 1: for it to do some of the useful work like 267 00:16:29,720 --> 00:16:33,240 Speaker 1: powering allowed speaker and thus alerting you that there is 268 00:16:33,280 --> 00:16:36,640 Speaker 1: in fact smoke in the area. Now. Yeager, being an 269 00:16:36,720 --> 00:16:40,120 Speaker 1: enterprising sort, partnered with Maine to launch a business offering 270 00:16:40,120 --> 00:16:43,440 Speaker 1: smoke detectors in the late nineteen forties. However, these detectors 271 00:16:43,480 --> 00:16:48,200 Speaker 1: weren't terribly practical because they required that high voltage to 272 00:16:48,360 --> 00:16:52,520 Speaker 1: operate to to create that ionization chamber, and homes were 273 00:16:52,560 --> 00:16:56,960 Speaker 1: not wired for that kind of high voltage, so that 274 00:16:57,360 --> 00:16:59,920 Speaker 1: meant that you couldn't really get one for your house. 275 00:17:00,120 --> 00:17:03,640 Speaker 1: They were mostly used again in big industrial settings where 276 00:17:03,640 --> 00:17:06,439 Speaker 1: you could wire things up for that kind of power. 277 00:17:07,040 --> 00:17:10,119 Speaker 1: The solution to this problem was already set in motion, 278 00:17:10,320 --> 00:17:13,520 Speaker 1: though at the time it was top secret. I'll get 279 00:17:13,520 --> 00:17:23,840 Speaker 1: to that after this quick break. Now, while the high 280 00:17:23,960 --> 00:17:28,240 Speaker 1: voltage smoke detectors weren't seen as practical from an implementation 281 00:17:28,280 --> 00:17:32,080 Speaker 1: standpoint for your average homeowner, it was undeniable that they 282 00:17:32,080 --> 00:17:35,320 Speaker 1: were useful, and this was particularly highlighted in the United 283 00:17:35,359 --> 00:17:38,560 Speaker 1: States by a tragedy that took place on December one, 284 00:17:38,880 --> 00:17:42,600 Speaker 1: ninety eight at the Roman Catholic School of Chicago, called 285 00:17:42,760 --> 00:17:46,800 Speaker 1: Our Lady of the Angels School. Now, the origins of 286 00:17:46,800 --> 00:17:50,280 Speaker 1: the fire have never been verified. No one knows exactly 287 00:17:50,480 --> 00:17:53,960 Speaker 1: what started it, but it appeared to begin in the 288 00:17:54,160 --> 00:17:58,119 Speaker 1: stairwell for the school, and the school had limited fire 289 00:17:58,160 --> 00:18:01,520 Speaker 1: prevention measures in place. The school itself was an older 290 00:18:01,600 --> 00:18:05,720 Speaker 1: building in Chicago and had been grandfathered into Chicago's safety 291 00:18:05,800 --> 00:18:10,120 Speaker 1: standards because it had previously met earlier regulations. So when 292 00:18:10,119 --> 00:18:14,080 Speaker 1: the city updated its fire safety regulations, one of the 293 00:18:14,119 --> 00:18:16,719 Speaker 1: policies there was that older buildings that had passed the 294 00:18:16,800 --> 00:18:22,800 Speaker 1: previous ones were considered safe. Students and staff were unaware 295 00:18:22,880 --> 00:18:25,119 Speaker 1: of the danger of the fire until it became a 296 00:18:25,119 --> 00:18:29,560 Speaker 1: critical threat, and more than ninety children died in that tragedy. 297 00:18:29,560 --> 00:18:33,240 Speaker 1: It was a truly horrifying event and it illustrated the 298 00:18:33,280 --> 00:18:37,880 Speaker 1: need to develop better fire detection and prevention methods. Research 299 00:18:37,920 --> 00:18:41,480 Speaker 1: in Canada and the United States began looking into various 300 00:18:41,840 --> 00:18:46,000 Speaker 1: catastrophic fires that had happened over the years, and according 301 00:18:46,040 --> 00:18:49,800 Speaker 1: to doctor Jim Milkey of the University of Maryland, these 302 00:18:49,800 --> 00:18:55,119 Speaker 1: studies found evidence suggesting that had smoke detectors been available 303 00:18:55,280 --> 00:18:59,440 Speaker 1: at the time, there would have been fewer deaths in 304 00:18:59,480 --> 00:19:03,040 Speaker 1: those catastrophic fires. Uh, there were more than three hundred 305 00:19:03,040 --> 00:19:06,080 Speaker 1: of them that they were looking at, and rise of 306 00:19:06,160 --> 00:19:08,880 Speaker 1: heat detectors, which I'll talk about in a second, would 307 00:19:08,920 --> 00:19:13,400 Speaker 1: have decreased the number of fatalities less than ten. And 308 00:19:13,480 --> 00:19:15,840 Speaker 1: these were hypotheses, mind you, you there's no way of 309 00:19:15,880 --> 00:19:18,600 Speaker 1: knowing that that in fact would actually have been the 310 00:19:18,640 --> 00:19:21,280 Speaker 1: way it played out. We only know what actually happened, 311 00:19:21,320 --> 00:19:24,280 Speaker 1: not what might have happened. But the scholars were pointing 312 00:19:24,280 --> 00:19:26,760 Speaker 1: out how the cause of death wasn't always due to 313 00:19:26,800 --> 00:19:30,960 Speaker 1: direct exposure to fire itself, which rise of heat detectors 314 00:19:30,960 --> 00:19:34,240 Speaker 1: would help you avoid, but exposure to smoke, and smoke 315 00:19:34,280 --> 00:19:37,679 Speaker 1: detectors might activate well in advance of a rise of 316 00:19:37,720 --> 00:19:41,080 Speaker 1: heat detector, giving people precious time to evacuate a building. 317 00:19:41,800 --> 00:19:44,640 Speaker 1: So that rise of heat detector, that's like the kind 318 00:19:44,720 --> 00:19:46,960 Speaker 1: I was talking about at the top of this episode. 319 00:19:47,240 --> 00:19:51,960 Speaker 1: It's the type that can uh monitor increases in temperature 320 00:19:52,080 --> 00:19:56,320 Speaker 1: and at a certain temperature they'll activate, they'll sound an alarm, 321 00:19:56,359 --> 00:19:58,440 Speaker 1: but by then it might be too late. So the 322 00:19:58,520 --> 00:20:02,159 Speaker 1: high voltage requirement for smoke detectors that ionized air that 323 00:20:02,280 --> 00:20:05,840 Speaker 1: had an ionization chamber was still a problem at this point. 324 00:20:05,920 --> 00:20:09,440 Speaker 1: They made them impractical and expensive, particularly for homeowners. It 325 00:20:09,600 --> 00:20:12,400 Speaker 1: was again more common for really big buildings like manufacturing 326 00:20:12,440 --> 00:20:15,320 Speaker 1: plants and factories and that kind of thing, and the 327 00:20:15,440 --> 00:20:17,600 Speaker 1: rise of heat detectors like the ones I first described 328 00:20:17,600 --> 00:20:19,800 Speaker 1: in this episode would also be used in those facilities. 329 00:20:20,040 --> 00:20:22,760 Speaker 1: So the solution to this problem of requiring high voltage 330 00:20:22,880 --> 00:20:25,520 Speaker 1: would have its roots in a top secret program that 331 00:20:25,560 --> 00:20:29,600 Speaker 1: had a very different aim seem Back in ninety there 332 00:20:29,640 --> 00:20:32,399 Speaker 1: was a guy named Glenn Seaborg who had been asked 333 00:20:32,400 --> 00:20:36,679 Speaker 1: to join the highly classified Manhattan Project. Now this was, 334 00:20:36,760 --> 00:20:41,040 Speaker 1: of course, the United States effort to find a way 335 00:20:41,080 --> 00:20:44,719 Speaker 1: to weaponize atomic energy to split the atom to release 336 00:20:44,760 --> 00:20:48,520 Speaker 1: an enormous and destructive force that could be used as 337 00:20:48,520 --> 00:20:52,760 Speaker 1: a weapon. Seaborg led a team that researched radioactive materials 338 00:20:53,080 --> 00:20:55,399 Speaker 1: as they tried to determine which of them would be 339 00:20:55,440 --> 00:20:58,639 Speaker 1: the most useful in a weapon like an atomic bomb. 340 00:20:59,119 --> 00:21:04,240 Speaker 1: They discovered in numerous radioactive elements in the process, elements 341 00:21:04,240 --> 00:21:07,280 Speaker 1: that are above ninety two on the elemental table. We're 342 00:21:07,280 --> 00:21:10,800 Speaker 1: all synthetic. They were all created in labs, and they're 343 00:21:11,240 --> 00:21:14,960 Speaker 1: very unstable atoms now. Among the ones that they worked 344 00:21:14,960 --> 00:21:19,199 Speaker 1: on was one called amerasirium. So a Mera sirium is 345 00:21:19,520 --> 00:21:24,840 Speaker 1: a synthetic h element that was produced in the lab 346 00:21:24,880 --> 00:21:29,000 Speaker 1: in a cyclotron experiment in Berkeley, California. The specific variant 347 00:21:29,160 --> 00:21:32,480 Speaker 1: that we're interested in for this podcast is an isotope 348 00:21:32,520 --> 00:21:35,040 Speaker 1: of a Mera cirium. It's a Mera cirium too forty one. 349 00:21:35,680 --> 00:21:37,639 Speaker 1: And you know I mentioned what ions are, but what 350 00:21:37,840 --> 00:21:40,760 Speaker 1: is an isotope in case it's been a while since 351 00:21:40,760 --> 00:21:43,520 Speaker 1: you've had basic science. Because I always have to look 352 00:21:43,560 --> 00:21:46,639 Speaker 1: these up. I'm not trying to shame anybody. I I 353 00:21:46,720 --> 00:21:49,080 Speaker 1: get my stuff mixed up, so I gotta look it up. Well. 354 00:21:49,200 --> 00:21:51,320 Speaker 1: You know, an ion is an atom or molecule that 355 00:21:51,359 --> 00:21:53,680 Speaker 1: has a net electric charge, right, the means that either 356 00:21:54,080 --> 00:21:56,800 Speaker 1: has too many or too few electron electrons for it 357 00:21:56,840 --> 00:21:59,840 Speaker 1: to balance out with the protons. That's an ion. I 358 00:22:00,000 --> 00:22:03,240 Speaker 1: aotopes are different. You have the the right number of 359 00:22:03,240 --> 00:22:07,200 Speaker 1: protons and electrons, but you have different numbers of neutrons 360 00:22:07,320 --> 00:22:11,960 Speaker 1: between two different two or more different variants of the 361 00:22:12,080 --> 00:22:16,160 Speaker 1: same element. So amerasirium two forty one and a Mera 362 00:22:16,280 --> 00:22:19,879 Speaker 1: sirium two forty two are nearly identical. They have the 363 00:22:19,920 --> 00:22:22,280 Speaker 1: same number of protons and the same number of electrons, 364 00:22:22,520 --> 00:22:26,280 Speaker 1: but a merasirium two forty two has one neutron more 365 00:22:26,640 --> 00:22:29,560 Speaker 1: than a Mera cirium too forty one. It changes the 366 00:22:29,600 --> 00:22:34,000 Speaker 1: atomic mass of that particular atom, but otherwise as the 367 00:22:34,040 --> 00:22:38,560 Speaker 1: same protons and electrons as the other isotopes of that element. 368 00:22:39,080 --> 00:22:42,760 Speaker 1: So a Mera cirium to forty one is radioactive, which 369 00:22:42,800 --> 00:22:47,919 Speaker 1: means it decays and gives off radiation. It's ionic radiation, 370 00:22:48,080 --> 00:22:51,040 Speaker 1: so that means that the energy that's given off, the 371 00:22:51,280 --> 00:22:55,200 Speaker 1: radiation that's given off is energetic enough to strip electrons 372 00:22:55,280 --> 00:22:59,040 Speaker 1: off of atoms or molecules and ionizing them. A small 373 00:22:59,080 --> 00:23:02,639 Speaker 1: amount of amerasium to forty one will ionize atoms like 374 00:23:02,680 --> 00:23:07,480 Speaker 1: oxygen and nitrogen just through the natural process of radioactive decay. 375 00:23:07,600 --> 00:23:09,880 Speaker 1: So what do I mean by a small amount. I'm 376 00:23:09,920 --> 00:23:14,119 Speaker 1: talking about one five thousand of a gram, so a 377 00:23:14,359 --> 00:23:21,000 Speaker 1: super tiny amount of radioactive material. Now, smoke detector manufacturers 378 00:23:21,040 --> 00:23:23,600 Speaker 1: did not immediately jump on a mera cirium as a 379 00:23:23,600 --> 00:23:27,399 Speaker 1: replacement for a high voltage circuit. That would take some 380 00:23:27,520 --> 00:23:31,200 Speaker 1: time and a lot of study before determining that amerasirium 381 00:23:31,400 --> 00:23:35,560 Speaker 1: was pretty safe to use under specific parameters. The type 382 00:23:35,560 --> 00:23:40,320 Speaker 1: of radiation gives off is primarily alpha radiation. There's alpha, beta, 383 00:23:40,359 --> 00:23:43,040 Speaker 1: and gamma radiation. I'll talk more about that in a 384 00:23:43,080 --> 00:23:47,919 Speaker 1: subsequent episode. But alpha radiation is the emission of alpha particles, 385 00:23:48,160 --> 00:23:50,920 Speaker 1: and an alpha particle is essentially the same thing as 386 00:23:50,920 --> 00:23:55,160 Speaker 1: a helium UH nucleus. UH. The nucleus of a helium 387 00:23:55,200 --> 00:23:59,479 Speaker 1: atom includes two protons and two neutrons. That's an alpha 388 00:23:59,480 --> 00:24:03,560 Speaker 1: particle two protons and two neutrons. An alpha particle has 389 00:24:03,720 --> 00:24:08,000 Speaker 1: good ionization power, but it also doesn't have a lot 390 00:24:08,000 --> 00:24:12,720 Speaker 1: of penetrative power. It can't go through matter very easily. 391 00:24:13,119 --> 00:24:16,000 Speaker 1: It's a massive particle in the grand scheme of things 392 00:24:16,600 --> 00:24:19,600 Speaker 1: UH and moves more slowly than other types of radiation. 393 00:24:20,040 --> 00:24:22,760 Speaker 1: So an alpha particle is too weak to pass through 394 00:24:22,800 --> 00:24:25,480 Speaker 1: a thin sheet of paper. It can only go through 395 00:24:25,520 --> 00:24:29,479 Speaker 1: a few centimeters of air before it loses energy and 396 00:24:29,520 --> 00:24:32,800 Speaker 1: can't move anymore. So, while embarrass serrium to forty one 397 00:24:33,160 --> 00:24:37,640 Speaker 1: is radioactive, it's considered relatively safe in small amounts, and 398 00:24:37,680 --> 00:24:40,880 Speaker 1: if kept in isolation. You wouldn't want to come into 399 00:24:40,920 --> 00:24:44,320 Speaker 1: direct contact with the stuff. And you definitely wouldn't want 400 00:24:44,359 --> 00:24:48,239 Speaker 1: to inhale or ingest any emiss cerium or get it 401 00:24:48,600 --> 00:24:52,080 Speaker 1: in an open wound because it is carcinogenic. But it 402 00:24:52,080 --> 00:24:55,320 Speaker 1: would have to get past barriers. It's not even strong 403 00:24:55,440 --> 00:24:58,359 Speaker 1: enough to get through the skin, but it is strong 404 00:24:58,440 --> 00:25:01,159 Speaker 1: enough if you were to ingest or breathe in some dust, 405 00:25:01,680 --> 00:25:05,679 Speaker 1: it could potentially cause cancer. It could certainly increase your 406 00:25:05,760 --> 00:25:09,959 Speaker 1: risk of developing cancer. So there is a danger to it. 407 00:25:10,359 --> 00:25:14,760 Speaker 1: So your typical smoke detector actually has some radioactive material 408 00:25:14,800 --> 00:25:17,400 Speaker 1: in it to create the ions that flow between two 409 00:25:17,480 --> 00:25:21,320 Speaker 1: charged plates. The ions behave just as the ones did 410 00:25:21,359 --> 00:25:24,639 Speaker 1: with Yeager's high voltage device. It's the same source stuff. 411 00:25:24,640 --> 00:25:28,320 Speaker 1: It's charged particles, So smoke particles will still interact with them, 412 00:25:28,359 --> 00:25:30,640 Speaker 1: just as they would with Yeager's invention with the high 413 00:25:30,720 --> 00:25:34,680 Speaker 1: voltage grid, and they will still bind and cause a 414 00:25:34,960 --> 00:25:37,280 Speaker 1: drop in current, and that's what triggers the circuit that 415 00:25:37,320 --> 00:25:40,879 Speaker 1: powers the actual alarm. Now, it would be nearly two 416 00:25:40,960 --> 00:25:46,040 Speaker 1: decades between the invention of amerasirium two forty one and 417 00:25:46,119 --> 00:25:49,480 Speaker 1: its application as an ion generator in a smoke detector. 418 00:25:49,880 --> 00:25:53,520 Speaker 1: The United States Atomic Energy Commission would grant a license 419 00:25:53,640 --> 00:25:57,040 Speaker 1: in nineteen sixty three authorizing the use of a Merra 420 00:25:57,119 --> 00:26:00,879 Speaker 1: cirium to forty one in smoked at hectors. And the 421 00:26:00,920 --> 00:26:04,800 Speaker 1: thought was that the amount of radioactive material that would 422 00:26:04,800 --> 00:26:09,440 Speaker 1: be so tiny that, uh, it would not really stand 423 00:26:09,480 --> 00:26:12,160 Speaker 1: to be a hazard, and it's just a very low risk. 424 00:26:12,680 --> 00:26:16,760 Speaker 1: But there was a very real risk of fire and smoke. 425 00:26:17,400 --> 00:26:20,480 Speaker 1: And so when you weighed it against each other and 426 00:26:20,520 --> 00:26:23,200 Speaker 1: said the risk of fire is high and the risk 427 00:26:23,359 --> 00:26:26,119 Speaker 1: of something happening because of this very tiny amount of 428 00:26:26,160 --> 00:26:29,320 Speaker 1: radioactive material is low, it makes way more sense to 429 00:26:29,600 --> 00:26:34,040 Speaker 1: air on the side of detecting fires. So two years later, 430 00:26:34,080 --> 00:26:39,679 Speaker 1: in a guy named Dwayne d Personal introduced a battery 431 00:26:39,800 --> 00:26:43,600 Speaker 1: powered smoke detector. This eliminated the need for that high 432 00:26:43,680 --> 00:26:47,840 Speaker 1: voltage circuit, and Personal came by this accidentally. A lot 433 00:26:47,840 --> 00:26:51,200 Speaker 1: of inventions really end up being created as a consequence 434 00:26:51,240 --> 00:26:54,480 Speaker 1: of some other unrelated effort. So in nineteen sixty three, 435 00:26:54,640 --> 00:26:58,280 Speaker 1: that same year where the Atomic Energy Commission granted the license, 436 00:26:58,920 --> 00:27:03,360 Speaker 1: Personal had been working on some tough problems with his employees. 437 00:27:03,600 --> 00:27:06,159 Speaker 1: Not problems with his employees, but with his employees. They 438 00:27:06,160 --> 00:27:09,080 Speaker 1: were working on tough problems. Personal was in a rough spot, 439 00:27:09,119 --> 00:27:10,919 Speaker 1: so he had taken out a second mortgage on his 440 00:27:11,000 --> 00:27:13,720 Speaker 1: house to create a company called Personal Company and a 441 00:27:13,760 --> 00:27:17,600 Speaker 1: spinoff company called Satra. To all are Sata Troll rather 442 00:27:18,040 --> 00:27:23,080 Speaker 1: Santatoral Corporation in Denver, Colorado. Uh I find that name 443 00:27:23,280 --> 00:27:25,920 Speaker 1: incredibly difficult to say properly. In fact, I'm sure I'm 444 00:27:25,920 --> 00:27:29,520 Speaker 1: saying it incorrectly. But anyway, the company's main business was 445 00:27:29,560 --> 00:27:33,800 Speaker 1: selling heating and air distribution equipment for commercial buildings, so 446 00:27:33,920 --> 00:27:38,080 Speaker 1: sort of like an HVAC company for big, big, big buildings. 447 00:27:38,119 --> 00:27:41,240 Speaker 1: But the products his engineers were working on was what 448 00:27:41,400 --> 00:27:44,920 Speaker 1: he called a static neutralizer. The idea was he was 449 00:27:44,960 --> 00:27:47,720 Speaker 1: going to create an ion generator, and the idea was 450 00:27:47,760 --> 00:27:52,840 Speaker 1: that these ions would neutralize static electricity build up on equipment, 451 00:27:53,200 --> 00:27:55,359 Speaker 1: and that's something that could be a real issue for 452 00:27:55,440 --> 00:27:59,080 Speaker 1: industrial operations and clean rooms and stuff. So you need 453 00:27:59,119 --> 00:28:01,439 Speaker 1: to have a way to new trill eyes static build up, 454 00:28:01,520 --> 00:28:03,359 Speaker 1: or else you can have a discharge that could ruin 455 00:28:04,200 --> 00:28:08,320 Speaker 1: tons of work. However, his team had encountered a problem. 456 00:28:08,359 --> 00:28:11,679 Speaker 1: They saw that their ion generator was getting clogged up 457 00:28:11,720 --> 00:28:15,920 Speaker 1: pretty quickly. The ions were attracting particles like dust and stuff, 458 00:28:16,480 --> 00:28:19,679 Speaker 1: and as it was attracting dust, it was starting to 459 00:28:20,119 --> 00:28:23,239 Speaker 1: make the entire device as a whole less effective. An 460 00:28:23,280 --> 00:28:26,639 Speaker 1: engineer named Lyman Blackwell was running tests to see what 461 00:28:26,720 --> 00:28:30,760 Speaker 1: could be done to keep the ion generation going. While 462 00:28:30,800 --> 00:28:33,919 Speaker 1: testing the system, they noticed that the ion meter they 463 00:28:33,960 --> 00:28:37,840 Speaker 1: were using to monitor performance would occasionally fluctuate, and one 464 00:28:37,840 --> 00:28:41,360 Speaker 1: of the technicians running the equipment was a smoker. He 465 00:28:41,480 --> 00:28:45,120 Speaker 1: was chained smoking during the whole testing process. Eventually, they 466 00:28:45,120 --> 00:28:47,760 Speaker 1: figured out that the meter was detecting fluctuations in the 467 00:28:47,840 --> 00:28:52,400 Speaker 1: ion flow whenever smoke was getting pulled in through the 468 00:28:52,440 --> 00:28:56,840 Speaker 1: fan on the generator and inserted into the ion stream. 469 00:28:56,920 --> 00:28:59,640 Speaker 1: So essentially they were making the same discovery that Yeager 470 00:28:59,720 --> 00:29:03,080 Speaker 1: had aid decades earlier, but the big difference was that 471 00:29:03,440 --> 00:29:07,480 Speaker 1: Purcell's ion generator didn't require that high voltage to run 472 00:29:07,560 --> 00:29:09,960 Speaker 1: because it was depending on that small amount of ameras 473 00:29:10,040 --> 00:29:12,840 Speaker 1: serium to forty one. So he had the bright idea 474 00:29:12,960 --> 00:29:15,800 Speaker 1: to take this unexpected result and turn it into an 475 00:29:15,840 --> 00:29:19,480 Speaker 1: actual product. Two years later, he had the first battery 476 00:29:19,560 --> 00:29:23,400 Speaker 1: operated ionization based smoke detector. He called it the Smoke 477 00:29:23,480 --> 00:29:26,760 Speaker 1: Guard seven hundred, but it wasn't quite ready for the 478 00:29:26,800 --> 00:29:30,120 Speaker 1: home market yet because government regulations had not yet caught 479 00:29:30,280 --> 00:29:33,440 Speaker 1: up to the technology. We're gonna get into that as well, because, 480 00:29:33,440 --> 00:29:35,360 Speaker 1: as it turns out, it's not enough just to make 481 00:29:35,400 --> 00:29:38,040 Speaker 1: tech that works. You have to make tech that works 482 00:29:38,080 --> 00:29:42,680 Speaker 1: within the boundaries of laws and regulations. Meanwhile, a pair 483 00:29:42,760 --> 00:29:47,360 Speaker 1: of inventors named Donald Steele and Robert Emerk came up 484 00:29:47,360 --> 00:29:51,240 Speaker 1: with an alternative method for detecting smoke with a with 485 00:29:51,320 --> 00:29:55,240 Speaker 1: a device, And this approach wouldn't used ionized particles at all, 486 00:29:55,360 --> 00:30:00,560 Speaker 1: so there's no need to create any sort of ionization chamber. Instead, 487 00:30:00,960 --> 00:30:04,360 Speaker 1: Steel and m Mark created a smoke detector that relied 488 00:30:04,440 --> 00:30:08,920 Speaker 1: upon light and photo detectors. So photo detectors those are 489 00:30:09,000 --> 00:30:12,560 Speaker 1: that's light sensors, rights a sensor that detects light. There 490 00:30:12,560 --> 00:30:15,720 Speaker 1: are two basic categories of light sensors. The first type 491 00:30:15,720 --> 00:30:20,480 Speaker 1: are sometimes called photovoltaics. These are devices that emit electrons 492 00:30:20,560 --> 00:30:23,880 Speaker 1: when they're exposed to light, So solar panels are a 493 00:30:23,880 --> 00:30:29,720 Speaker 1: type of photovoltaic cells, uh they generate electricity when exposed 494 00:30:29,720 --> 00:30:32,760 Speaker 1: to light. The other type of light sensor would be 495 00:30:32,800 --> 00:30:36,560 Speaker 1: the photo resistor or photo conductor. These sensors have electrical 496 00:30:36,560 --> 00:30:41,480 Speaker 1: properties that change if they are actually exposed to light. So, 497 00:30:41,640 --> 00:30:45,520 Speaker 1: for example, a photo resistor has a relatively high electrical 498 00:30:45,600 --> 00:30:49,600 Speaker 1: resistance when it's in the dark, so that material resists 499 00:30:49,640 --> 00:30:53,040 Speaker 1: the flow of electricity going through it. However, as the 500 00:30:53,080 --> 00:30:57,800 Speaker 1: material is exposed to light, the electrical resistance decreases, an 501 00:30:57,840 --> 00:31:00,960 Speaker 1: electricity can pass through it more readily. So if you 502 00:31:01,000 --> 00:31:03,400 Speaker 1: place one of these devices in a circuit and you 503 00:31:03,440 --> 00:31:07,040 Speaker 1: have a voltage detector also attached to that circuit, the 504 00:31:07,120 --> 00:31:10,480 Speaker 1: detector will pick up changes in voltage as light hits 505 00:31:10,560 --> 00:31:15,880 Speaker 1: the sensor. Now, you could try and build a smoke 506 00:31:15,960 --> 00:31:19,200 Speaker 1: detector that works by having a light shining on a 507 00:31:19,240 --> 00:31:22,800 Speaker 1: photo sensor of some sort that's at least partially open 508 00:31:22,880 --> 00:31:25,800 Speaker 1: to the air outside of the detector, and if something 509 00:31:25,840 --> 00:31:30,680 Speaker 1: like smoke were to enter that pathway the direct detector's events, 510 00:31:30,680 --> 00:31:33,640 Speaker 1: and it somehow gets in between the light and the sensor. 511 00:31:34,400 --> 00:31:38,720 Speaker 1: Then you would have smoke obscuring or blocking some of 512 00:31:38,760 --> 00:31:41,560 Speaker 1: that light, and if it were enough, then the alarm 513 00:31:41,560 --> 00:31:44,080 Speaker 1: would go off. But that actually wouldn't be a very 514 00:31:44,080 --> 00:31:47,280 Speaker 1: sensitive smoke detector. It wouldn't work unless the smoke was 515 00:31:47,320 --> 00:31:50,200 Speaker 1: thick enough to really cause an issue. It's actually pretty 516 00:31:50,240 --> 00:31:54,560 Speaker 1: tricky for a sensor to detect dips in light intensity, 517 00:31:55,160 --> 00:31:57,520 Speaker 1: and by the time it would the smoke might be 518 00:31:57,560 --> 00:32:00,240 Speaker 1: thick enough to already be a major threat to people's safety. 519 00:32:00,440 --> 00:32:02,959 Speaker 1: But there's a clever work around to this. So instead 520 00:32:02,960 --> 00:32:05,360 Speaker 1: of an alarm that goes off when a light no 521 00:32:05,560 --> 00:32:09,920 Speaker 1: longer is shining on it, designer system where the alarm 522 00:32:09,960 --> 00:32:13,520 Speaker 1: goes off if the sensor detects light. Even a small 523 00:32:13,560 --> 00:32:17,120 Speaker 1: amount of light can create enough of a signal for 524 00:32:17,160 --> 00:32:20,880 Speaker 1: it to send a message to start the alarm. So 525 00:32:20,920 --> 00:32:23,960 Speaker 1: in this version, you've got a light that's shining down 526 00:32:24,000 --> 00:32:27,160 Speaker 1: a pathway. So imagine a chamber. You've got a light 527 00:32:27,200 --> 00:32:31,520 Speaker 1: at one end, and uh it's open, so that air 528 00:32:31,640 --> 00:32:35,280 Speaker 1: can come into the chamber nine at a nine degree angle, 529 00:32:35,440 --> 00:32:38,600 Speaker 1: like a perpendicular angle to this light and tucked away 530 00:32:38,720 --> 00:32:41,280 Speaker 1: just a bit back. You have a little alcove where 531 00:32:41,320 --> 00:32:44,720 Speaker 1: there's a sensor. So under normal conditions, the light is 532 00:32:44,760 --> 00:32:47,200 Speaker 1: going through the chamber, but the sensor is tucked in 533 00:32:47,320 --> 00:32:50,360 Speaker 1: at a right angle, so it's not picking up any light. 534 00:32:50,440 --> 00:32:54,800 Speaker 1: The sensor stays in the dark. However, if smoke enters 535 00:32:54,880 --> 00:32:58,239 Speaker 1: the chamber that the light is passing through, some of 536 00:32:58,240 --> 00:33:01,960 Speaker 1: that light hits the smoke and starts to scatter. And 537 00:33:02,000 --> 00:33:03,800 Speaker 1: this is the same sort of effect you would see 538 00:33:03,840 --> 00:33:07,280 Speaker 1: if you were driving a car on a really foggy day. 539 00:33:07,320 --> 00:33:09,440 Speaker 1: That's why you're not supposed to use the high beams 540 00:33:09,480 --> 00:33:12,000 Speaker 1: on your headlights when you're in the fog. The light 541 00:33:12,040 --> 00:33:14,640 Speaker 1: will hit the fog and scatter. It's more likely to 542 00:33:14,680 --> 00:33:17,600 Speaker 1: make it harder for you to see rather than easier. 543 00:33:18,120 --> 00:33:21,680 Speaker 1: When the smoke detector, some of that scattered light hits 544 00:33:21,720 --> 00:33:24,680 Speaker 1: the sensor, which then activates a signal to the alarm. 545 00:33:25,240 --> 00:33:28,760 Speaker 1: And that approach allows for far more sensitivity In a 546 00:33:28,840 --> 00:33:32,680 Speaker 1: smoke detector. They can go off much faster than one 547 00:33:32,800 --> 00:33:36,280 Speaker 1: that would require the smoke to block the light. So 548 00:33:36,320 --> 00:33:38,560 Speaker 1: a dark sensor picking up on light is just more 549 00:33:38,600 --> 00:33:42,120 Speaker 1: reliable than a lit up sensor trying to detect a 550 00:33:42,240 --> 00:33:46,120 Speaker 1: dip in brightness. However, it's also not fool proof because 551 00:33:46,240 --> 00:33:50,440 Speaker 1: vapor or dust could cause false alarms. Now, during all 552 00:33:50,440 --> 00:33:54,240 Speaker 1: this innovation, changes were starting to happen on regulatory levels 553 00:33:54,240 --> 00:33:56,520 Speaker 1: around the world. And when we come back, I'll talk 554 00:33:56,600 --> 00:33:58,800 Speaker 1: more about how that played out in the United States. 555 00:33:58,800 --> 00:34:08,759 Speaker 1: But first let's take an their quick break. All right, 556 00:34:08,800 --> 00:34:12,480 Speaker 1: So now we've got the basic technology of smoke detectors understood, 557 00:34:12,560 --> 00:34:15,760 Speaker 1: let's talk about regulations. See, if you're going to produce 558 00:34:15,920 --> 00:34:20,120 Speaker 1: and market something that's meant to protect lives, it's often 559 00:34:20,160 --> 00:34:23,560 Speaker 1: the case that a government agency or two will take 560 00:34:23,600 --> 00:34:26,239 Speaker 1: notice and they want to make sure that the thing 561 00:34:26,320 --> 00:34:30,040 Speaker 1: you're making does what you claim it does it if 562 00:34:30,200 --> 00:34:33,239 Speaker 1: lives literally hang in the balance, it's important. So this 563 00:34:33,320 --> 00:34:36,960 Speaker 1: is the same basic underlying philosophy we see an agencies 564 00:34:37,000 --> 00:34:41,360 Speaker 1: that monitor stuff like food processing and pharmaceutical development and production. 565 00:34:42,160 --> 00:34:45,360 Speaker 1: The era I'm talking about in the late nineteen sixties 566 00:34:45,400 --> 00:34:49,239 Speaker 1: in the United States was a particularly tumultuous time. You 567 00:34:49,280 --> 00:34:53,280 Speaker 1: had the Civil rights movement, you had America's involvement in Vietnam, 568 00:34:53,320 --> 00:34:57,640 Speaker 1: and other really politically charged events playing out in the US, 569 00:34:58,080 --> 00:35:01,920 Speaker 1: and these were sparks pun in tended that ignited civil 570 00:35:02,040 --> 00:35:06,360 Speaker 1: unrest across the entire country, and in turn that was 571 00:35:06,400 --> 00:35:10,799 Speaker 1: testing the limits of police forces and fire prevention and 572 00:35:10,920 --> 00:35:19,200 Speaker 1: fire uh extinguishing services. So this prompted the US Congress 573 00:35:19,200 --> 00:35:23,640 Speaker 1: to re examine policies around safety to better protect citizens. 574 00:35:24,239 --> 00:35:26,560 Speaker 1: One thing to come out of this was the Fire 575 00:35:26,640 --> 00:35:29,560 Speaker 1: Research and Safety Act, which was signed into law by 576 00:35:29,600 --> 00:35:34,080 Speaker 1: then President Lyndon Johnson. The President was citing some figures 577 00:35:34,080 --> 00:35:37,440 Speaker 1: that suggested as many as twelve thousand Americans had died 578 00:35:37,520 --> 00:35:42,160 Speaker 1: in fires in nineteen sixties. Six Later estimates adjusted that 579 00:35:42,239 --> 00:35:45,200 Speaker 1: number down significantly to like eight thousand, but that's still 580 00:35:45,239 --> 00:35:48,680 Speaker 1: way too many people. The Act called for the creation 581 00:35:48,760 --> 00:35:52,400 Speaker 1: of a twenty person panel to study the challenges and 582 00:35:52,480 --> 00:35:56,920 Speaker 1: make recommendations for new safety standards that could be carried 583 00:35:56,960 --> 00:36:00,200 Speaker 1: out at the federal level and require any building in 584 00:36:00,239 --> 00:36:03,960 Speaker 1: the US to follow certain processes to make sure that 585 00:36:04,000 --> 00:36:06,279 Speaker 1: they were safe for people. And it took a few 586 00:36:06,360 --> 00:36:09,200 Speaker 1: years for all of this to actually coalesce into a report. 587 00:36:09,719 --> 00:36:13,040 Speaker 1: I mean, it was a big task, and we also 588 00:36:13,239 --> 00:36:15,760 Speaker 1: happen to know that things in the U. S. Government 589 00:36:15,800 --> 00:36:20,319 Speaker 1: don't go super fast. But in nineteen seventy three, the 590 00:36:20,360 --> 00:36:24,560 Speaker 1: panel released a report. The report was titled America Burning, 591 00:36:24,840 --> 00:36:28,759 Speaker 1: which is pretty sobering all on its own, and America 592 00:36:28,920 --> 00:36:32,160 Speaker 1: was leading the way in industrial nations when it came 593 00:36:32,200 --> 00:36:35,840 Speaker 1: to per capita deaths and property loss due to fire. 594 00:36:36,400 --> 00:36:39,920 Speaker 1: So the argument they were making was that America is 595 00:36:39,960 --> 00:36:43,320 Speaker 1: this incredibly advanced country, Why the heck are we losing 596 00:36:43,400 --> 00:36:45,600 Speaker 1: so much to fire? We should be doing better than that, 597 00:36:46,320 --> 00:36:50,279 Speaker 1: And of the deaths were occurring in people's homes. The 598 00:36:50,360 --> 00:36:56,480 Speaker 1: report also contained pictures of Person's smoke guard detector. He 599 00:36:56,600 --> 00:37:00,440 Speaker 1: had come to overcome challenges to make his detector practical 600 00:37:00,480 --> 00:37:04,960 Speaker 1: and safe, and his original design did not have a battery. Instead, 601 00:37:04,960 --> 00:37:07,600 Speaker 1: it was to be hardwired into the electrical system of 602 00:37:07,640 --> 00:37:11,319 Speaker 1: a building. It didn't require two twenty volts like the 603 00:37:11,400 --> 00:37:14,920 Speaker 1: earlier smoke detectors of Switzerland did, but it still was 604 00:37:14,960 --> 00:37:18,680 Speaker 1: an expensive proposition and it made it an unlikely candidate 605 00:37:18,719 --> 00:37:22,000 Speaker 1: for home adoption because every unit would set someone back 606 00:37:22,040 --> 00:37:24,799 Speaker 1: about a thousand dollars at the time, which would be 607 00:37:24,840 --> 00:37:28,000 Speaker 1: a lot more than that today. So his team was 608 00:37:28,080 --> 00:37:30,680 Speaker 1: able to create a version that would operate on battery power, 609 00:37:31,040 --> 00:37:33,440 Speaker 1: which was already an engineering triumph, but they need to 610 00:37:33,480 --> 00:37:37,200 Speaker 1: figure out how to make this a reliable one, or 611 00:37:37,320 --> 00:37:40,920 Speaker 1: to convince people that it was reliable, because batteries, as 612 00:37:40,920 --> 00:37:45,360 Speaker 1: we all know, eventually exhaust themselves. The chemical reactions inside 613 00:37:45,360 --> 00:37:50,120 Speaker 1: a battery are what produces electrons, and over time you 614 00:37:50,120 --> 00:37:52,040 Speaker 1: get to a point where there's been enough of the 615 00:37:52,120 --> 00:37:55,040 Speaker 1: chemical reaction going on that you don't have the active 616 00:37:55,160 --> 00:38:00,360 Speaker 1: ingredients necessary to sustain that that supply of electricity anymore, 617 00:38:00,960 --> 00:38:03,839 Speaker 1: and not the proper voltage anyway. And we're talking about 618 00:38:03,880 --> 00:38:06,680 Speaker 1: something as critical as a smoke detector, that's a real problem. 619 00:38:07,080 --> 00:38:10,920 Speaker 1: So his team solved this issue by creating circuits that 620 00:38:10,920 --> 00:38:15,520 Speaker 1: would send a chirping alarm to the smoke detector if 621 00:38:15,640 --> 00:38:19,040 Speaker 1: it detected a drop in voltage across the primary circuit 622 00:38:19,120 --> 00:38:21,960 Speaker 1: of the smoke detector. So the chirp wouldn't require very 623 00:38:22,000 --> 00:38:25,400 Speaker 1: much energy of itself, and it would be repeated until 624 00:38:25,520 --> 00:38:28,479 Speaker 1: the voltage across the circuit returned to the proper level, 625 00:38:28,480 --> 00:38:31,560 Speaker 1: in other words, until the battery was replaced. In addition, 626 00:38:31,880 --> 00:38:35,600 Speaker 1: Personal included a small card in the box for the 627 00:38:35,600 --> 00:38:38,920 Speaker 1: smoke guards seven, and customers were meant to take the 628 00:38:38,960 --> 00:38:42,400 Speaker 1: card and then fill out little forms on the card 629 00:38:42,600 --> 00:38:45,959 Speaker 1: with their own information, including their address and the date 630 00:38:46,120 --> 00:38:49,759 Speaker 1: that they installed their smoke detector, and Personal's company would 631 00:38:49,760 --> 00:38:53,439 Speaker 1: actually mail out an annual reminder to its customers saying, hey, 632 00:38:53,560 --> 00:38:55,319 Speaker 1: it's time for you to replace the battery and your 633 00:38:55,360 --> 00:38:58,880 Speaker 1: smoke detector. In order to keep it operational. Personal worked 634 00:38:58,960 --> 00:39:03,480 Speaker 1: closely with safety officials and organizations both to improve his 635 00:39:03,520 --> 00:39:07,160 Speaker 1: smoke detectors and make them more useful, and also to 636 00:39:07,200 --> 00:39:11,239 Speaker 1: help shape policy so that these detectors would be recognized 637 00:39:11,280 --> 00:39:13,600 Speaker 1: as effective and a good option to help curb the 638 00:39:13,600 --> 00:39:17,600 Speaker 1: problem of fatalities due to fire disasters, and the work 639 00:39:17,600 --> 00:39:20,080 Speaker 1: paid off both for Personal and for people in general. 640 00:39:20,200 --> 00:39:23,040 Speaker 1: He was able to convince officials that a battery powered 641 00:39:23,080 --> 00:39:27,080 Speaker 1: smoke detector was effective if it had the ability to 642 00:39:27,120 --> 00:39:30,719 Speaker 1: alert occupants of a dying battery. The government actually would 643 00:39:30,719 --> 00:39:34,800 Speaker 1: mandate that the chirping alarm sound should last at least 644 00:39:35,000 --> 00:39:38,880 Speaker 1: seven consecutive days in an effort to alert homeowners to 645 00:39:39,040 --> 00:39:41,480 Speaker 1: change out a battery. And this was specifically in case 646 00:39:41,719 --> 00:39:43,800 Speaker 1: so I might be out of town when the battery 647 00:39:43,800 --> 00:39:46,719 Speaker 1: starts to give out. They wanted it to last long 648 00:39:46,840 --> 00:39:48,720 Speaker 1: enough so that you would have time to get back 649 00:39:49,160 --> 00:39:51,080 Speaker 1: and find out. Oh gosh, I need to switch out 650 00:39:51,080 --> 00:39:53,719 Speaker 1: the batteries on my smoke detector. The government also had 651 00:39:53,760 --> 00:39:56,720 Speaker 1: to balance out the cost of installing fire prevention systems 652 00:39:56,719 --> 00:40:01,720 Speaker 1: and homes, including in newly constructed homes. Initially, plans called 653 00:40:01,760 --> 00:40:06,000 Speaker 1: for both smoke detectors and rise of heat detectors. However, 654 00:40:06,440 --> 00:40:09,879 Speaker 1: after numerous studies, the government concluded that rise of heat 655 00:40:09,880 --> 00:40:13,120 Speaker 1: detectors weren't really practical if you were looking at trying 656 00:40:13,160 --> 00:40:16,120 Speaker 1: to save lives. They just they just weren't good enough 657 00:40:16,200 --> 00:40:19,799 Speaker 1: to do that, and they were really expensive, and that 658 00:40:19,920 --> 00:40:24,720 Speaker 1: smoke detectors were much better for the purpose of preventing fatalities. 659 00:40:25,239 --> 00:40:27,200 Speaker 1: And so that meant that they got rid of the 660 00:40:27,320 --> 00:40:31,160 Speaker 1: rise of heat detector requirement, and that helped bring the 661 00:40:31,200 --> 00:40:35,000 Speaker 1: cost down of implementing fire protection systems and homes, and 662 00:40:35,040 --> 00:40:37,960 Speaker 1: that in turn increased the likelihood that people would actually 663 00:40:37,960 --> 00:40:42,280 Speaker 1: follow the rules and adopt smoke detectors. The regulations paved 664 00:40:42,280 --> 00:40:44,960 Speaker 1: the way for Personal to manufacture, market, and sell his 665 00:40:45,000 --> 00:40:48,120 Speaker 1: smoke detectors to the American public, who could be reassured 666 00:40:48,160 --> 00:40:51,000 Speaker 1: that the devices would actually provide a valuable and potentially 667 00:40:51,040 --> 00:40:54,080 Speaker 1: life saving service. He scaled up his company to meet 668 00:40:54,120 --> 00:40:57,800 Speaker 1: demand before eventually selling it off in nineteen seventy seven. 669 00:40:58,120 --> 00:41:00,480 Speaker 1: And from everything I've read about him, it sounds like 670 00:41:00,520 --> 00:41:03,960 Speaker 1: he was motivated not only by an entrepreneurial spirit, although 671 00:41:04,000 --> 00:41:07,440 Speaker 1: he certainly had that, but also a genuine desire to 672 00:41:07,440 --> 00:41:10,480 Speaker 1: make his community and the world a better place if 673 00:41:10,560 --> 00:41:13,759 Speaker 1: he could, And I think that's pretty cool. Since the 674 00:41:13,800 --> 00:41:18,480 Speaker 1: introduction of the optical and the ionization chamber based smoke detectors, 675 00:41:18,880 --> 00:41:22,240 Speaker 1: we've seen some innovations, but the basic principles all remain 676 00:41:22,320 --> 00:41:26,640 Speaker 1: the same. There are smoke detectors that incorporate both types 677 00:41:26,640 --> 00:41:30,279 Speaker 1: of methodologies, meaning there are smoke detectors that have independent 678 00:41:30,320 --> 00:41:33,600 Speaker 1: systems to detect the presence of smoke, and we've seen 679 00:41:33,719 --> 00:41:36,960 Speaker 1: some incorporate other types of text such as network connectivity 680 00:41:37,000 --> 00:41:40,240 Speaker 1: in the form of products like the Nest Protect smoke detector, 681 00:41:40,960 --> 00:41:44,120 Speaker 1: and those smoke detectors add a little more functionality to 682 00:41:44,200 --> 00:41:47,280 Speaker 1: the basic kind. They work on basically the same principle, 683 00:41:47,640 --> 00:41:51,799 Speaker 1: but they have some more features. For example, they can 684 00:41:51,800 --> 00:41:55,560 Speaker 1: send information across a local area network wirelessly, and then 685 00:41:55,600 --> 00:41:58,399 Speaker 1: that network can send an alert to you on an 686 00:41:58,400 --> 00:42:01,080 Speaker 1: app on a smartphone, and that could be valuable if, 687 00:42:01,120 --> 00:42:03,280 Speaker 1: for example, you're away from your home. When an alarm 688 00:42:03,360 --> 00:42:06,840 Speaker 1: goes off to give you a notification, you can perhaps 689 00:42:08,000 --> 00:42:10,040 Speaker 1: either call home, or if no one's home, you might 690 00:42:10,120 --> 00:42:12,080 Speaker 1: even call a fire department to go and check on 691 00:42:12,080 --> 00:42:14,640 Speaker 1: your home to make sure that everything is all right. 692 00:42:15,080 --> 00:42:18,359 Speaker 1: And most homes have multiple smoke detectors. In fact, you're 693 00:42:18,400 --> 00:42:21,680 Speaker 1: supposed to have one outside of every bedroom, for example, 694 00:42:21,680 --> 00:42:24,040 Speaker 1: as well as maybe one in the kitchen. My own 695 00:42:24,080 --> 00:42:28,319 Speaker 1: home has six of the darned things, and there could 696 00:42:28,320 --> 00:42:31,720 Speaker 1: be an issue of figuring out which detector is going off, 697 00:42:31,800 --> 00:42:36,879 Speaker 1: and that could be of vital importance. So with connected detectors, 698 00:42:37,239 --> 00:42:40,520 Speaker 1: then you get a notification saying detector number three is 699 00:42:40,560 --> 00:42:43,120 Speaker 1: going off, and you know that number three happens to 700 00:42:43,120 --> 00:42:46,880 Speaker 1: be outside the guest room, so you would be able 701 00:42:46,920 --> 00:42:50,640 Speaker 1: to very quickly figure out what's going on, as opposed 702 00:42:50,680 --> 00:42:53,680 Speaker 1: to trying to determine which of your numerous alarms is 703 00:42:53,680 --> 00:42:56,960 Speaker 1: going off. It also means that if a battery is 704 00:42:57,000 --> 00:43:00,360 Speaker 1: running out and a smoke detector is chure ing, or 705 00:43:00,400 --> 00:43:03,040 Speaker 1: maybe a battery was just a bad battery and starts 706 00:43:03,080 --> 00:43:06,320 Speaker 1: to chirp, you get more quickly track down which detector 707 00:43:06,560 --> 00:43:10,680 Speaker 1: is making the chirping noise. This really applies to folks 708 00:43:10,719 --> 00:43:13,320 Speaker 1: like me because I live in a townhouse that has 709 00:43:13,360 --> 00:43:16,120 Speaker 1: a few floors, and the center of the townhouse is 710 00:43:16,200 --> 00:43:19,200 Speaker 1: essentially like a chimney. There are stairs that go from 711 00:43:19,200 --> 00:43:23,440 Speaker 1: the bottom floor, and the stairwells open all the way 712 00:43:23,480 --> 00:43:27,080 Speaker 1: to the top of the town house, so it's like 713 00:43:27,120 --> 00:43:30,479 Speaker 1: an echo chamber inside my house, which means when something 714 00:43:30,520 --> 00:43:33,360 Speaker 1: like a smoke detector starts to chirp, I can't easily 715 00:43:33,440 --> 00:43:36,319 Speaker 1: identify whether it's on the floor I'm on the floor 716 00:43:36,360 --> 00:43:39,319 Speaker 1: above me or the floor below me. And I have 717 00:43:39,480 --> 00:43:43,160 Speaker 1: six smoke detectors. If it's time to replace the batteries, 718 00:43:43,400 --> 00:43:45,600 Speaker 1: that's one thing, But if it's just that a battery 719 00:43:45,719 --> 00:43:48,919 Speaker 1: is going bad early, then I have to figure out 720 00:43:48,920 --> 00:43:53,280 Speaker 1: which of those detectors is making the problem. And exacerbating 721 00:43:53,520 --> 00:43:55,920 Speaker 1: this issue for me is the fact that I have 722 00:43:55,960 --> 00:43:59,480 Speaker 1: a cute little doggie named Timbolt, and the chirping smoke 723 00:43:59,560 --> 00:44:04,200 Speaker 1: detector noise causes him intense distress, like he starts to 724 00:44:04,560 --> 00:44:09,680 Speaker 1: shake with fear. So I get really upset when one 725 00:44:09,680 --> 00:44:13,160 Speaker 1: of my smoke detectors starts to chirp prematurely. There's no 726 00:44:13,200 --> 00:44:16,200 Speaker 1: smoke or anything, it's just giving me a chirp alarm, 727 00:44:16,760 --> 00:44:19,560 Speaker 1: but that's a me problem. One other thing that a 728 00:44:19,560 --> 00:44:22,239 Speaker 1: lot of smoke detectors can do these days is they 729 00:44:22,239 --> 00:44:28,120 Speaker 1: can also perform as carbon monoxide detectors. So carbon monoxide 730 00:44:28,520 --> 00:44:32,280 Speaker 1: is an odorless and colorless gas, so human beings can't 731 00:44:32,320 --> 00:44:36,400 Speaker 1: easily detect it, and it's also toxic. It's a byproduct 732 00:44:36,400 --> 00:44:39,759 Speaker 1: from burning carbon based fuels like gasoline, heating oil, or 733 00:44:39,840 --> 00:44:43,840 Speaker 1: natural gas, and in confined spaces it can be really 734 00:44:43,960 --> 00:44:47,399 Speaker 1: dangerous stuff, so like a garage, for example. And while 735 00:44:47,400 --> 00:44:51,360 Speaker 1: we humans can't really detect carbon monoxide with our own senses, 736 00:44:51,760 --> 00:44:53,520 Speaker 1: there are a lot of other ways to see if 737 00:44:53,560 --> 00:44:56,919 Speaker 1: the stuff is around. So carbon monoxide detectors can work 738 00:44:57,000 --> 00:45:00,239 Speaker 1: using one of a few different methods. Upon detect action, 739 00:45:00,280 --> 00:45:02,480 Speaker 1: they basically do the same thing as a smoke detector. 740 00:45:02,520 --> 00:45:04,880 Speaker 1: They send a signal to sound an alarm, but the 741 00:45:04,960 --> 00:45:08,760 Speaker 1: way they detect the carbon monoxide can be a little different. 742 00:45:09,520 --> 00:45:13,560 Speaker 1: So there are three basic approaches to this uh and 743 00:45:13,800 --> 00:45:17,880 Speaker 1: one you might have what are called bio mimetic sensors. 744 00:45:17,920 --> 00:45:23,440 Speaker 1: These sensors mimic, thus the name some sort of biological functions, 745 00:45:23,440 --> 00:45:28,080 Speaker 1: such as hemoglobin, which interacts with carbon monoxide. So These 746 00:45:28,120 --> 00:45:31,880 Speaker 1: sensors have a gel inside of them, and that gel 747 00:45:31,920 --> 00:45:36,799 Speaker 1: can absorb carbon monoxide. As the gel does absorb carbon monoxide, 748 00:45:36,840 --> 00:45:40,839 Speaker 1: the gel changes color. You have a separate sensor that's 749 00:45:40,920 --> 00:45:44,760 Speaker 1: monitoring the color of the gel, and if the gel changes, 750 00:45:45,320 --> 00:45:48,200 Speaker 1: then the sensor picks up on that change and sends 751 00:45:48,239 --> 00:45:51,720 Speaker 1: a signal to the alarm. UH. These sensors can actually 752 00:45:51,719 --> 00:45:54,960 Speaker 1: be reset. The gel will return to its original color 753 00:45:55,400 --> 00:45:59,600 Speaker 1: once it it gets rid of that carbon monoxide, but 754 00:45:59,680 --> 00:46:01,879 Speaker 1: it has to be set in an environment that's free 755 00:46:01,880 --> 00:46:04,480 Speaker 1: of carbon monoxide for several hours in order to reset. 756 00:46:05,200 --> 00:46:09,600 Speaker 1: The next type is the metal oxide semiconductor sensor. This 757 00:46:09,640 --> 00:46:12,640 Speaker 1: has components to have a certain level of electrical resistance, 758 00:46:12,719 --> 00:46:15,800 Speaker 1: very much like the optical smoke detectors I talked about earlier. 759 00:46:16,239 --> 00:46:19,160 Speaker 1: So these components react with carbon monoxide in a way 760 00:46:19,200 --> 00:46:23,839 Speaker 1: that lowers the materials electrical resistance, and so meters are 761 00:46:23,840 --> 00:46:27,040 Speaker 1: monitoring a voltage across a circuit and if it detects 762 00:46:27,080 --> 00:46:32,920 Speaker 1: this change in voltage, then it will send a signal 763 00:46:33,239 --> 00:46:36,360 Speaker 1: to the alarm. And the third type of sensor that 764 00:46:36,480 --> 00:46:39,480 Speaker 1: you could find in a carbon monoxide detector is an 765 00:46:39,480 --> 00:46:44,240 Speaker 1: electrochemical sensor. These sensors also detect changes an electrical current 766 00:46:44,719 --> 00:46:48,080 Speaker 1: in the presence of carbon monoxide, but they have electrodes 767 00:46:48,120 --> 00:46:52,600 Speaker 1: that are inside a chemical solution, so they're actually engulfed 768 00:46:52,640 --> 00:46:56,120 Speaker 1: in a chemical solution around these electrodes, and the chemicals 769 00:46:56,120 --> 00:46:59,160 Speaker 1: in the solution react very very quickly in the presence 770 00:46:59,160 --> 00:47:03,839 Speaker 1: of carbon monox eide, and that changes the electrical qualities 771 00:47:04,000 --> 00:47:07,320 Speaker 1: of the the solution, which means that you are able 772 00:47:07,320 --> 00:47:11,000 Speaker 1: to detect a change in the circuit very very quickly. 773 00:47:11,040 --> 00:47:15,320 Speaker 1: In fact, this stuff is used in professional settings. Uh, 774 00:47:15,440 --> 00:47:18,200 Speaker 1: it's a very sensitive kind of alarm. Today, there are 775 00:47:18,200 --> 00:47:20,759 Speaker 1: a lot of smoke detectors that double as carbon monoxide 776 00:47:20,760 --> 00:47:24,879 Speaker 1: detectors with separate components monitoring the environment. And that's all 777 00:47:24,880 --> 00:47:28,920 Speaker 1: smoke detectors work. Uh. It's a fascinating journey letting us 778 00:47:29,080 --> 00:47:32,920 Speaker 1: learn a lot about physics, including nuclear physics, and we 779 00:47:32,960 --> 00:47:36,280 Speaker 1: will be talking more about nuclear physics in our next episode. 780 00:47:36,280 --> 00:47:41,600 Speaker 1: We'll talk about radiation and Geiger counters and uh, the 781 00:47:41,640 --> 00:47:45,920 Speaker 1: discoveries that were made that really taught us all about radiation, 782 00:47:45,960 --> 00:47:49,440 Speaker 1: and a lot of those discoveries came at a significant 783 00:47:49,560 --> 00:47:55,440 Speaker 1: human cost. But that's an episode for our next tech stuff. 784 00:47:56,040 --> 00:48:00,000 Speaker 1: This particular episode is now concluded, so if you guys 785 00:48:00,040 --> 00:48:03,160 Speaker 1: have suggestions for future episodes of tech Stuff, reach out 786 00:48:03,160 --> 00:48:05,799 Speaker 1: to me on social media. We are at Facebook and 787 00:48:05,840 --> 00:48:08,719 Speaker 1: we are at Twitter with the handle text stuff H 788 00:48:08,920 --> 00:48:12,359 Speaker 1: s W and I'll talk to you again really soon. 789 00:48:16,800 --> 00:48:19,000 Speaker 1: Text Stuff is a production of I Heart Radio's How 790 00:48:19,080 --> 00:48:22,480 Speaker 1: Stuff Works. For more podcasts from my heart Radio, visit 791 00:48:22,480 --> 00:48:25,600 Speaker 1: the i heart Radio app, Apple Podcasts, or wherever you 792 00:48:25,640 --> 00:48:27,000 Speaker 1: listen to your favorite shows.