Rerun: Lighting Up the Holidays

on November two thousand nineteen. It is titled Lighting Up the Holidays, and as you might guess, it's about the incorporation of electric lights in particular in holiday celebrations, and also you know, talking a little bit about Stranger Things and why it was a challenge to make the holiday lights light up in the way they do in the first season of Stranger Things. So sit back, relax, and

enjoy this episode about lighting up the Holidays. Now, before I dive into all of that, I want to acknowledge

a few things first. While I'll be talking about Christmas lights, there are many people of different faiths, ethnicities, regions, etcetera who celebrates special days during the winter months, and lights nearly always play an important part in those various observations, which makes total sense because the days are shorter in the winter, and thus we have more hours of darkness for every twenty four hour period, so lights would clearly be an important part of any celebration during that part

of the year. So, for example, the manora in the Jewish faith symbolizes how the Maccabees, when rededicating the Holy Temple, which they had just won back from the Greeks, used a single bottle of oil to light the manora used in the rededication ceremony for eight nights, even though the bottle should only have lasted a single night. Then there's also the celebration of Kwanza, where families like candles in the cannara, and the candles represent the seven principles of

the holiday. But getting back to Christmas lights, there's actually an older tradition than the sort of Christmas tree lights, in which Christian families would set out candles within view of a window as a symbol to alert fellow Christians that the family inside the house was they were made up of observing Christians, and that fellow Christians would be welcome to come into that house to worship with the family.

But the Christmas lights we see every year really have their roots pun intended in a Germanic tradition of the Christmas tree. So why would you ever cut down a tree and bring it inside in the first place. Well, again, one of those things that makes sense as you start to think about all the details. Plants like fur trees and holly remain green even in the winter, which otherwise pretty much wipes out everything else and makes it brown and dead, so or appearing to be dead. So these

plants became symbols of resilience and everlasting life. So people would cut down some of those plants and bring them indoors to remind them of that. But you know, then the plants would eventually just dry out and turn brown, and thus negate the whole reason for bringing them inside.

But you know, humans have never been rational creatures. There are some unsupported legends surrounding the origins of the German Christmas tree uh sometimes referred to as the Tannenbaum, but really Tannenbaum is more of a word for fur trees in general, not just those all decked out with bowls

of holly and whatnot. But one legend has it that Martin Luther, the Reformer, who caused a bit of a Ruckus in the fifteen hundreds, when he, you know, decided to criticize the Catholic Church that he had started the tradition of the Christmas tree. However, the earliest written accounts on record that mentioned this tradition date to six oh five. Now that doesn't mean that's when the tradition started, of course, it's just the earliest written account that we happen to have.

Scholars think the tradition might date back at least to the mid sixteenth century, though that would still be after Martin Luther had died. So anyway, that sixteen o five account, all it says is that the people would set up Christmas trees in their rooms in Strasbourg. There's no mention of lights in this particular account, but the decorations consisted of things like roses made out of paper and various foods being shoved into the tree, things like apples or

cookies and sugar. It's very food centric. In fact, there was a tradition of raiding the Christmas tree on one of the days of Christmas, where the kids get to go and actually grab treats from the tree and eat them. The first written account to bring up the detail about lights in the Christmas tree dates to sixteen sixty. People in Germany would pin or otherwise attached candles to branches of these trees, and again, frequently these are trees that have been cut down and put up inside a house,

not just trees out in the woods somewhere. Generally speaking, the practice was to light the candles only for a very short time before you blew them out again. And you were never supposed to leave a tree unattended, because, as you can imagine, combining a cut tree that might be kind of dry with open flames is a recipe for disaster. And in fact, there were more than a few cases of fires with these trees, some of them

ending in catastrophe and tragedy. But I'm sure the effect was really nice, leaning right up to the moment where everything went ablaze. Okay, so let's skip ahead to the eighteen hundreds. At that point the tradition extended beyond Germany. Harvard professor named Charles Fallen, inspired by stories that he had heard in Europe, did a lit up Christmas tree here in America. This was believed to be the first lit Christmas tree in America, or at least the first

one on record. In the eighteen forties, in England, Queen Victoria and Prince Albert had a Christmas tree famously depicted in an illustration that was published in a newspaper that likely helped boost the practice over in England. Prince Albert brought this over from his homeland in Saxony. So people came up with new ways to attach the candles to trees, you know, they found more improved methods that would catch the wax and things like that. However, there was still

very much a danger of fire with this particular approach. Then, in the later eighteen hundreds we get to Thomas Edison, the inventor and entrepreneur who was spending a lot of time and resources trying to perfect the light bulb. Which he did not invent the light bulb, but he did improve upon it, or rather, I should say his lab

improved upon it. So when he and his engineers managed to make a light bulb that could last more than just a few hours and could be suitable for general use as opposed to stuff like the more dangerous arc lamps that, while extremely bright, were not practical for everyday applications, he then had to figure out a way, how do I sell this idea to cities, right to city officials and then further onto the general public. So he wanted to convince Manhattan officials that his company should be the

one to provide electricity and light all of Manhattan. So he had his employees hang lights during the holiday season in eighteen eighty on the outside of Menlo Park, which was an easy view of trains passing by, and it got a lot of attention. Now, one of the inventors who was working at his Menlo Park facility was Edward

Hibbert Johnson. Johnson had actually been responsible for giving Edison a job at the Automatic Telegraph Company, but later on Johnson would end up working closely with Edison to develop Menlo Park itself and became an inventor and executive at the Edison Light Company. So it's funny because he helped get Edison a job early and then he ended up

working for Edison later. It was at the Menlo Park facility where Johnson developed string lights, and these were lights that were wired together in series and would serve as the basis for Christmas lights. Just moving forward from that point, he used those lights to decorate a Christmas tree and so Johnson is sometimes referred to as the father of electric Christmas tree lights because the original version, the earlier version that Edison did that was a string of lights

they hung up on a building. This was the first time where someone was using electric Christmas lights to replace the candles that were found on the Germanic Christmas trees. His lights, by the way, had bulbs that were red, white, and blue. Is quite the patriotic Christmas tree, and like Edison, Johnson intended that for this not just to be a festive display in the spirit of America and the holiday season, but also a marketing effort to get more people to

support and want and adopt electric lights. There was a general distrust in electricity around this time, so these were the ways in which Edison and his associates could try to win people over to this new technology, and adoption did not take off right away. So for one thing, no New York based reporters wrote about this Christmas tree at all, but one reporter for a Detroit newspaper did publish an account of what it was like seeing the

Christmas tree all lit up. The next big development in the adoption of Christmas lights would come in eight when US President Grover Cleveland incorporated them in decorations for the Christmas Tree at the White House. So we're gonna go off on a little tangent here some fun trivia facts about Grover Cleveland. So he's the only US president whoever served two non consecutive terms, meaning he was both our twenty second and our twenty fourth president of the United States.

The lighting of the Christmas tree would be during his second term as president. And just in case you're wondering the twenty third president, the one who interrupted those two terms was Benjamin Harrison, the grandson of our ninth President, William Henry Harrison. Sorry, I recently, I've been showing up on a lot of ridiculous history episodes and sometimes that

stuff just gonna sticks with you. Anyway. Cleveland's Tree, Grover Cleveland's tree featured one hundred lights with bulbs of various colors, and it must have been a really impressive site for the time. Some of the movers and shakers in America, in other words, people had a ton of cash to burn. They began to put up their own decorated and lit Christmas trees. But it was not something the average person

could do. Because at that time, most of the United States wasn't wired for electricity, so to even have a lit Christmas tree with electric lights, you would have to set up a generator. You'd also typically have to hire an electrician to actually wire it up, and in today's money, that would mean that decorating a tree could cost at least a couple of thousands of dollars, So only the hoity toity folks who wanted to show off their wealth could really afford to have a Christmas tree with electric

lights at that time. Anyway, over the course of the early nineteen hundreds, electric lights began to gain popularity as people became more comfortable with the idea of electricity. And it's really no wonder that folks were nervous at first. Fire is something you can see, at least in most cases,

but electricity could be deadly but was also invisible. And Edison's company had already engaged in some pretty heavy smear campaigns against alternating current, since Edison was pushing direct current as a means to distribute electricity regionally, and a lot of those events and demonstrations that his company held involves showing off how deadly electricity could be, so they were kind of feeding into that fear. But the allure of the lights was undeniable. And with that, I mean not

just Christmas lights. I mean you're running of the mill light bulbs. Now. Even in n three, when General Electric introduced string Christmas light kits, which will let people string up their own lights at home without necessarily the use of an electrician, it was still really expensive a string of lights, and General Electric actually referred to these strings

as festoons. Anyway. The string of lights consisted of eight whole light bulb sockets and they would hold Edison light bulbs and it cost the equivalent of about three hundred dollars today. That's just the lights, and this was not something that the average family would necessarily spring for. Also, you wouldn't buy these kits. You would rent them for three hundred dollars, so after the rental period you would

actually have to return them. So yikes. Now, the bulbs on these things were small, round bulbs, almost like manature incandescent light bulbs. Actually that's exactly what they were, but I'm talking more about the form factor rather than the actual lighting mechanism. In nineteen nineteen, General Electric introduced a new bulb shape and filament. It was more of a flame shape, is that sort of classic, large, kind of clunky,

retro looking light bulb. That was the general shape that they introduced, and it had a filament made out of Mazda toungusten. The filament is the part of the incandescent bulb that actually glows. The company would use Mazda filaments in all sorts of lamp bulbs, not just Christmas ones. Now, there were a couple of possibly apocryphal stories about some smaller companies around this time that played an important role

in popularizing Christmas lights. One of those stories is about a telephone company employee named Ralph E. Morris who at some point. Different versions of this story can date it to either eight, the same year that Grover Cleveland was

lighting up the White House, or nineteen o eight. There's a pretty big discrepancy, but the stories say that he looked at a telephone switchboard, and telephone switchboards had these little tiny light bulbs mounted in them that would light up when you were making connections, and he thought those

little light bulbs might make nice Christmas decorations. So he took a bunch of those little lightbulbs, a bunch of telephone wire, wired them all together, electrified the wire, and made up a little lit Christmas tree, a little fake lit Christmas tree, because the story says that he made a makeshift Christmas tree out of feathers. I don't know exactly how he did it, but that's what the story says. His son would later write an article claiming that his

father invented Christmas lights, which wasn't quite accurate. They predated this, but I'm pretty sure it was an honest mistake, not something that was done, you know, maliciously. Now. The other, possibly an apocryphal story involves a guy named Albert Sadaka. This story goes that when Sedaka was fifteen, he heard about a terrible tragedy involving a deadly fire that began when a Christmas tree lit with candles fire and people

died as a result. His family made novelty lights with white bulbs, so he thought, hey, how about we change out those regular bulbs with bulbs of different colors and we use electric lights instead of candles to light up a Christmas tree. According to this story, he and his brothers began to do just that, and a few years later, they led an effort to bring together several small competing

light companies. They're all going for the same customers, and they formed the National Outfit Manufacturers Association, or NOMA, which would become its own company and by became the leading manufacturing company for electric Christmas lights. Now, as power companies wired up the United States for electricity, the popularity of

electric Christmas lights began to grow. In nineteen twenty, a hardware store owner in California named Frederick Nash decorated trees outside his establishment, and that quickly grew into a tradition in which a nine block stretch of the road in front of his business would end up having trees just draped in lights, and it became the first big documented

outdoor Christmas lights display. When we come back, i'll talk more about the evolution of Christmas lights, and then we'll dive into how the heck they work, and in the case of traditional Christmas lights, how they don't work if just one bulb goes bad. But let's take a quick break. I've got a little bit more to go on to the history of Christmas lights and some of the interesting things about them before we get into how they work.

So by the late nineteen thirties, electric Christmas lights had become a popular new tradition, with homeowners and businesses alike uh using them to create bright, colorful displays, and in some cases they went a little bit overboard. A few places became truly famous for their decorated trees and buildings.

When the United States entered into World War Two and there was an learn about the possibility of cities being bombed, there were blackout orders in various cities like New York, and that meant that Christmas lights would actually go dark in nineteen forty four in New York City, but with the war's end the following year, people made up for lost time. Meanwhile, tastes began to change. In America, families in the late nineteen fifties were introduced to a new invention,

the aluminium Christmas tree. Yeah, I can't even I can't believe this this really happened either, guys. These were trees made out of aluminium, a space age material that was clearly so much better than a freshly cut fir tree. However, the Christmas lights of the day, which were still incandescent bulbs in sometimes questionable wires, would get way too hot for aluminium trees. They also could potentially create an electric

shock hazard because aluminum can conduct electricity. Plus, those aluminium trees had needles quote unquote made out of foil, which would easily melt. So instead of hanging electric lights on the tree, companies began to manufacture lamps that had a rotating color wheel. And it's just what it sounds like, and it's not all that different from what was inside

old mechanical television sets before electric TV was invented. So you've got a bulb that's what provides the light, kind of like a projector, and in front of the bulb, you have a wheel that has different panes of colored plastic, and this wheel rotates past the bulb, and different colors of light shine out of your glorious lamp towards your even more glorious aluminum Christmas tree. It was a thing, y'all. Now, I can't say I personally found it appealing, but back

then it was selling like gangbusters. Unfortunately for companies like Noma, the leading manufacturer of Christmas lights, it meant that there was a drastic drop in Christmas lights sales as these aluminium trees became all the eight Noma would actually end up going into bankruptcy, and today it exists as a

brand name. But that's about it. The era of the aluminum tree lasted about a decade, upon which time many people either went back to using the previously live trees or they switched to more natural looking artificial trees, and that meant the electric lights were back baby. However, because of the American manufacturers going out of business during the reign of aluminum Terror, the Christmas lights on the market mostly came from other countries, so America would no longer

be king of the electric Christmas light all right. Now we're getting up to about nineteen seventy and the introduction of the mini light. So for a very long time, the typical Christmas light was a five or ten watt bulb, typically the size of a night light bulb, those little kind of cone shaped bulbs that I was talking about, the retro style, They were pretty big. These were the type of lights that I grew up with when I was a kid. That's the kind we had on our trees,

the big, big, bright lights. I still miss those. But they drew a lot of power because the string of fifty five what bulbs means that you're consuming two fifty what's and most people were using multiple strands, like one string wouldn't do it. You might have three strands, three to five for a tree, maybe five to ten for your house. So you're consuming an enormous amount of power

when you're having this stuff lit up. So the Christmas lights were greedy for electricity, then they pushed electric bills pretty high. They would also get really hot, which you know I mentioned back with the aluminium trees. Touching a bulb could give you a little bit of a minor burn, as I found out on more than one occasion when I was a kid, because I had three qualities that

guaranteed I was gonna get burned. First, I was curious. Second, I was foolish or maybe stupid, and third I had a really short memory, I guess anyway, the bulbs were popular. They were colorful, but they were also wasteful and expensive. The mini light would become a popular alternative to that bulky, hot, expensive Christmas light of the past. The mini lights are, as the name implies, smaller, They only need two point five volts of electricity, and they don't get nearly as hot.

Although they are still incandescent bulbs, so they still do generate heat. They're just not as hot as those larger bulbs were. It does, however, raise a question, how do you supply electricity to a two and a half volt socket if your source is an outlet that's putting out a hundred twenty volts. This is a good time to transition into a talk about circuits. So a quick reminder in electricity, voltage is sort of like water pressure in a water system. It's how hard the electricity is being

pushed through. You can think of it like that. It's not exactly the same, but that's a rough analogy. It's the behind the movement of electricity, and a one volts supply far overshadows a two and a half volt load. So imagine like having a fire hose of water directed at you. You've got a little shot glass that you're filling up and dumping out. It would just be way too much. But these Christmas lights were chained together in series, which meant one bulb socket connects to the next bulb

socket in the same circuit and so on. So if you've got two two and a half volt sockets, you end up with a load that requires five volts. If you were to multiply two and a half volts by I don't know, let's say forty eight, you'd get a hundred twenty. So yeah, if you string together forty eight light bulb sockets and each one of those is a two and a half volt socket, you end up with a full load what requires a hundred twenty volts. Problem

solved now. Typically companies would actually bump that up to fifty light sockets per series, and those extra two socket would mean that each individual bulb would be slightly, maybe even imperceptibly dimmer than it would be if you only had forty eight, but it wouldn't be so dim that it would make a huge difference. So imagine a pathway from an electric outlet that goes down a line of wires, and those wires connect to fifty bulbs in series, so

bulb one, the bulb two, the bulb three, etcetera. This represents the path that electricity takes, and along the way, the electricity is doing work in the form of producing light with those little light bulbs. And here's where a drawback of Christmas lights comes in. Let's say one of those bulbs burns out. Well, a burnt out bulb is

going to break that pathway for the electricity. It opens the circuit, and because the path is broken and electricity needs that clear unbroken path, the whole string of lights will go out. This is how Christmas lights used to be, where you'd have to go down a line of dark lights and you would swap out one bulb for another.

Over and over. You would be searching for the one bulb that caused the problem, and often it would lead to people chucking out a string entirely and just replacing it because trying to find that one bird's out bulb and a string of fifty just wasn't fun. And it was even worse if more than one bulb had been affected, because you might replace one bad bulb and never know it because there's a second or third bad bulb in

that same string. It was infuriating. Now, on top of that, later electric lights would have even longer strings, like one hundred, hundred fifty or two hundred lights. Not in order to achieve this, because I was just talking about how if you put these in series it creates that greater load. Well, engineers were able to kind of cheat with this they were using both series circuits and parallel circuits for these lights. Now, as I mentioned, a series circuit strings one electric load

after another along the same electrical path or circuit. So you can think of that as like one long street with houses on either side of the street, and houses represent the load on the electric circuit. So in this example, with a string that has fifty lights, think of a street and there are fifty houses twenty five on either side of the street. So to visit a house a little further down the street, you have to pass all

the other ones first. Parallel circuits create multiple paths, a an independent pathway for each circuit, so different loads are on their own distinct pathways. So with a string of one fifty Christmas lights, for example, you would actually have three fifty lights series circuits. Right, So you've got one string of fifty lights in series, a second string of fifty lights in series, and a third string of fifty

lights in series. But all three are then connected in parallel with each other in the street analogy, this would be like having three parallel streets that all connect to the same main road. Now, with this kind of string of lights, if un bulb were to go out, only the other bulbs in that same series circuit would go dark. So with a hundred fifty light string, it would mean

one third of those lights would go dark. Right, fifty lights would go out, but the other one hundred would stay lit because they were actually still in those parallel circuits. They were independent of that one fifty light string. You still have a problem with a third of your lights going dark, though, Engineers figured out how to solve this issue by creating what's called a shunt. Now, essentially, a shunt is an alternative circuitry path that electricity can pass

through even if a load has otherwise failed. So in this case, if a light bulb were to burn out, the light bulb would go dark, but the shunt would take over as the path for electricity to flow through, and that way the other bulbs in that series would still stay lit. So how does that work. Well, First, the shunt is lined with insulating material and that boosts

the electric resistance of the shunt. And this is important because if the shunt had an equal or lower electrical resistance, then the filament inside the lightbulb, the electricity would bypass the bulb all together and just go through the shunt. That means you wouldn't have a string of Christmas lights. Instead, you would have a really bad extension cord that was eating up a lot of power. And more than that, it would start to heat up and could potentially pose

as a fire hazard. And that's no bueno. So this is a good opportunity to talk about short circuits. A short circuit and I am not talking about the movie that featured Johnny five the Robot. A short circuit is when electricity encounters a pathway of lower resistance than the path it is supposed to follow. And yeah, the path of least resistance is a thing. We see it in nature all the time. If there are multiple ways for something to happen, the way that has the least obstacles

tends to be the one we end up with. So electricity is going through its circuit Do do Do Do, and suddenly there's a detour. Something has made contact with the circuit that represents a lower resistance pathway. The electricity takes the lower resistance pathway. That's just nature. The electricity skips out on doing whatever it was supposed to do, like light a light bulb, and rushes down this new path. Now, at a steady voltage, This means you get a spike

in current. This is because the voltage is that pressure I was talking about, and the pressure remains the same, but the reduction and electrical resistance means it's easier for electricity to flow through that part of the circuit. So the current has to increase. We expressed this mathematically by saying voltage is current times resistance, So if voltage is

staying the same, it's not changing and electrical resistance is decreasing. Current, by mathematical definition, has to increase to make up the difference, and increase in current can become dangerous or even deadly. Now, because of that risk, engineers began to include fuses in Christmas lights. The fuse in a Christmas light is kind of a strip of thin wire that's near the plug end of a string of lights, the part that actually

plugs into the wall. That's where the fuse is. It's rated for a certain maximum of current, and if the current increases beyond that maximum because of a short typically then this wire will actually kind of burn through and then it leaves a gap, and that gap ends up having such a high electrical resistance that electricity cannot flow through the string of lights and they all go dark.

So the fuse is typically replaceable, and in these strings of lights you can even open up a little window and put in a replacement fuse if the one that you have in there has burnt out for any reason. So that is sort of a safety measure in case of a short circuit. All right, now, let's get back

to the shunt. So this insulating wire that's around this this shunt typically wraps around the base of the filament in a Christmas light bulb, and because it has a higher electrical resistance than the filament does, electricity is not going to go through the shunt normally, it'll go through the filament instead. Now, if the filament begins to burn out, it starts to get really hot, and that heat is enough to melt the insulating material off of the shunt.

So the bulb burns out, the shunt wire essentially sheds its insulation it's melted off. As a result, the shunt becomes a lower resistance pathway for electricity, and electricity can then pass through the light bulb socket and keep the other lights on the series lit. It means you can actually spot the burnout bulb in a string and replace it. You don't have to worry about one bulb going out and everything going out. You'll just see that one bulb

burnout and you can then swap it out. Now, one other thing that can happen that can be for sustrating is that some of the strings of lights are pretty cheaply made, and the bulbs can be loose in their sockets, and if they're not making good contact with the parts of the socket where the electricity flows through, then you're not gonna get electricity flowing through the series, because it'll be like an open circuit or a circuit where the

switches in the off position. So in that case, you have to go down the length of the wire and check to make sure that each bulb is plugged in properly for electricity to flow through that series of bulbs. Some Christmas lights actually put the shunt into the socket itself rather than inside the bulb, which helps side stuff that problem. So in those cases, just like with a burnt out bulb, the affected bulb would be the one that was not lit, but the rest of it should

still be shining brightly. Now, when we come back, I'll talk a bit more about how the series Circuits and Christmas Lights created a headache for the electricians on the Netflix series Stranger Things, as well as a couple of other interesting facts. But first, let's take a quick break. Okay, So, in case you've not seen the series Stranger Things, let me explain why Christmas lights are important and why they posed a big challenge to the crew of that show.

So in the show, there's a boy named Will Buyers who is trapped in a sort of parallel dimension and he can't interact directly with people in our dimension, but he discovers that he can affect electrical devices. The show is set in the nineteen eighties and Will comes from sort of a lower middle class family and they still have the big, bulky Christmas lights they haven't switched over

to the smaller ones. And when Will's mother, Joyce, figures out that Will can affect these lights, she devises away for him to communicate with her. She labels a string of Christmas lights with letters of the alphabet, and that means Will can effectively type out messages by making individ will lights go off and on, which is a clever

idea for a show. It's also not how Christmas lights work, because, as I've described in this podcast, they're supposed to all be in series and you can't turn them off and on individually because they're all in a series circuit. They're strung in such a way that turning off one means they all go off. So how did the show get around that? Well? It was surprisingly challenging. The solution was

sort of straightforward, but it wasn't easy or convenient. The electrician had to wire each bulb individually to a switchboard that could supply electricity to that bulb. Now, that also meant having to control the voltage that was going to each bulb since they were no longer in series and the load wouldn't be shared across the whole wire. So you had to control the voltage to be appropriate for the individual bulbs and then isolate it from all the

other bulbs. And you had to do it twenty six times, or at least however many time was needed to make sure all the letters that were being used were wired up properly. You might have been able to get away without wiring up say X or Z or some of the other letters that aren't a common The switchboard was effectively a keyboard, so you could like press the a button that would activate a switch, and the switch would open the circuit, meaning it breaks the pathway, And because

it breaks the pathway, the light would go out. And if you close the circuit, if you close the switch, that would restore the pathway the light bulb would come on again. So that wiring was probably a huge pain in the neck because it meant having to do this for multiple letters and making sure each set of wires had the appropriate label on the switchboard, not to mention being sure that no bulb was going to get too

much voltage for it to handle. And on top of that, the wiring had to be hidden so the camera would make it look like it was just a normal string of Christmas lights. You couldn't see all these individual wires going to each bulb. It would break the illusion. So while you wouldn't call this a high tech special effect, it was one that required a lot of work and trial by error to get it just right to produce

the effect that the series directors were looking for. Now, we're not quite done with the evolution of Christmas lights. We've got a few more things to chat about. As the novelty song The Twelve Pains of Christmas reveals Christmas lights present their own frustrating challenges. If they're not stored properly, they become a tangled mess. There's the problem of one

going out and then they all go out. If you have a shuntless kind of string of Christmas lights at any rate, then there's the line that used to make me crack up as a kid. This will tell you how sophisticated my sense of humor was, and who my kidding still is. The line is, now, why the hell are they all blinking? Yeah, blinking lights? Okay, there are two general ways of creating blinking Christmas lights if you're a manufacturer. One of those ways is brilliantly simple and

kind of jankie. So let's go with that one first. All right, So let's say get a couple of different metals, and you create a strip using these two different metals. Maybe one side is copper and the other side is you know, iron or something. These two metals have slightly different properties, and one of the different properties they have is their rate of expansion when they get hot. Because one metal will expand faster than the other, it causes the strip to bend, it curls as one side of

the strip expands faster than the other one does. These are called bimetallic strips, and they're using lots of stuff like thermostats, but thermostats are a different podcast. Alright, So you've got this bimetallic strip and you use it to make a circuit path to a filament on a light bulb. So the strip itself is acting like a kind of wire. Electricity is passing through the strip to the filament, But then the filament starts to heat up, and when it heats up, it causes the strip to start to bend.

Because of that expansion thing I was just talking about. The strip bends to a point where it no longer makes contact with the filament, and since the electricity was flowing through the strip, it means the electrical path is broken, right because there's no more contact between the strip and the filament, no more electricity goes to the filament, and

so the light blinks out. Further, This bulb, called a blinker bulb, doesn't have a shunt in it, so when it goes out, all the other lights in that series blink out at the same time. Then the bimetallic strip begins to cool down because the filament is no longer glowing, so it's no longer putting off heat. And as it begins to cool down, it straightens out again. And when it straightens out, it makes contact with the filament, which causes the circuit to re establish and the lights come

on again. This process repeats itself over and over until the blinker bulb finally burns out and you have to replace the darn thing. Now, I love this approach because it's a low tech, practical way to create blinking lights, and it even includes a little mechanical element in the form of those bending strips. I think it's pun intended brilliant. Now, the other way to make blinking lights is also brilliant, but it's a bit more sophisticated. There are strings of

lights that come with sixteen function controllers. These controllers have four transistors, each of which drives a separate strand of lights, so the full string of lights is made up of four strands of lights. Further, these lights on these these full strands are in an interleaving pattern, meaning that you don't just get all the lights in one strand followed by all the lights in the second strand and so on.

The string would interleave these strands, so you could have something like light one from Strand one, light one from strand to, light one from Strand three, light one from Strand four, light two from Strand one, and so on. And that way you can apply different effects to each strand in the full string, and you could get really interesting results. Otherwise you might end up with a tree in which the first fifty lights are blinking, the next fifty lights are fading in and out, the next fifty

are twinkling, etcetera. So by doing it this way, you can have that effects spread out throughout the entire string of lights, and you get a more interesting, varied effect. More recently, we've seen LED lights start to replace the old incandescent many lights. The incandescent bulbs work by feeding electricity through a filament which heats up and gives off light, but LED lights generate light in a totally different way. L E D s have electrons moving through a semiconductor material.

Now I've talked about this in past episodes, and frankly, I'm running out of time in this episode, so I don't feel like I can really go into a lot of detail here about how it works, but from a sub atomic level, here's what's going on. You've got an electron inhabiting a certain energy shell around the nucleus of an atom. You pour some energy into that atom that causes the electron to jump to a higher energy shell

a little further out from the atoms nucleus. But then you cut off the energy that's going into the atom, and the electrons natural state is to be closer to the nucleus. But in order to move back to where it's supposed to be at first has to give off that excess energy, which it does so by emitting the energy in the form of photons or light, and they do it in very specific frequencies, so with different semiconductors

you can produce different colors of light. One nice thing about L E d s is that when an LED light fails, which typically takes a long time, LED lights tend to last much longer than incandescent lights. Anyway, the failed L E ED can still serve as a pathway for electricity to flow through, so the other lights on the string will continue to stay lit. It's more or less that like the L E ED is is in itself,

acting like a shunt. Led lights, just like other Christmas lights, tend to be wired in series, and you have multiple series of lights wired in parallel on a single string. And another great thing about LED lights is that they typically require way less energy to run, so you can run them longer and for less money in the long

run than you can with classic incandescent bulbs. They tend to be more expensive than incandescent bulb lights are on initial purchase, but in the long run you actually save money by using those, and you save a lot of energy. So highly recommended h and one type of bulb I didn't mention, I skipped over it, but this was a favorite of mine when I was growing up are bubble lights, which made a comeback not too long ago, but these

were like common when I was a kid. These lights have a fluid with a relatively low boiling point, and it's inside of a glass tube and at the base of the tube is an incandescent bulb. So when the bulb lights up, it gives off heat. Then eventually that heat reaches the temperature sufficient to bring the liquid inside the tube to a boil, which produces bubbles inside the tube. Now we had these on our Christmas trees when I was a kid, and I thought they were super awesome.

The early versions of these lights used a very lightweight oil as the liquid, but more modern versions tend to rely upon die chlora methane, which has a boiling point of thirty nine point six degrees celsius or a hundred three point three degrees fahrenheit. Oh And on the other end of the spectrum are the projector systems being used to create all sorts of effects on house exteriors, like snowfall or I don't know, an ELF strike team descending

on a house. These projectors typically use LEDs to generate lasers to create the light needed for the projection. The light passes through lenses that magnify whatever images are being displayed and then shoots them up so that they appear on the side of a house. And lasers are pretty nifty. They're also super technical, and I've talked about them another episodes, so I won't go into detail here, but I wanted to mention them because it's another high tech gadget being

used in holiday decorations these days. Also, um, if you have one of these things, make sure that it's pointed at your house and not the sky, because lasers have been known to cause problems for pilots because that light can be seriously powerful, so you know, just be responsible. There are other lights I can mention. They're like micro lights and mesh lights and icicle lights, but essentially all of these are variations upon the stuff I've already talked

about in this episode. And then there are the Christmas light displays that synchronize the lights with the soundtrack using various micro controllers and sequencers. And maybe I'll do a full episode about that kind of stuff in the future, but for now, I say it's time for lights out. I hope you enjoyed that episode from two thousand nineteen on lighting up the Holidays. I hope that your own

holidays have been happy, healthy and safe. I hope you're staying warm wherever you are, unless you're in Australia, in which case I hope you're staying cool. And I look forward to chatting with you again tomorrow. I should be back with more episodes about the big tech news stories of two because gosh darn it, there were just so many this past year. And let me know what else you would like me to chat about in three by

reaching out on Twitter. The handle for the show is tech Stuff h s W. Or you can download the i Heart Radio app for free and navigate on over to tech Stuff using that little search field and use the little microphone icon to leave me a voice message up to thirty seconds in length and tell me there and until then, I'll talk to you again really soon.

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