November 27, 2019 • 44 mins
We look at the history of incorporating lights in winter holidays like Christmas and Hanukkah and how electricity changed things dramatically. We'll also dive into those over the top displays that sequence lights with sound and talk about why it was such a challenge for the electrician on Stranger Things to make lights blink a specific way.
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Episode Transcript
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Speaker 1 (00:04):
Welcome to Tech Stuff, a production of I Heart Radios
How Stuff Works. Hey there, and welcome to tech Stuff.
I'm your host, Jonathan Strickland. I'm an executive producer with
iHeart Radio and I love all things tech, And you know, guys,
I was trying to come up with a good idea
for a holiday themed show. In the past, I've done
(00:26):
episodes about some of the big tech items that landed
on holiday wish lists in the past, you know, like
the greatest tech gifts of all time. But I felt
like I've been there, I've done that, And besides, a
lot of those topics are like super timely and aren't
relevant from year to year, so it makes no sense
to ever listen to them after the year they published.
(00:46):
So instead of doing an episode that's going to be
irrelevant next year, I thought I would talk about Christmas
lights and how they work and why it was such
a pain in the neck to rig up special Christmas
lights for the Netflix series Stranger Things, which I've talked
about in a previous episode, but I figured it would
be a good point to return to in this one. Now,
(01:07):
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,
(01:27):
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
(01:49):
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 Quanza, 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
(02:12):
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.
(02:33):
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
(02:54):
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
(03:15):
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
(03:38):
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
(03:58):
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,
(04:19):
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,
(04:42):
and sugar. It's very food centricum. 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
(05:06):
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
(05:28):
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 leading 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.
(05:51):
UH Harvard professor named Charles Fallen, inspired by stories that
he had heard in Europe, did a lit up Christmas
tree 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
(06:12):
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
(06:33):
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
(06:54):
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
(07:18):
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
(07:38):
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
(08:00):
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
(08:21):
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,
(08:43):
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
(09:04):
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
(09:25):
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
(09:46):
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
(10:09):
terms was Benjamin Harrison, the grandson of our ninth President,
William Henry Harrison. Sorry, 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,
(10:31):
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
(10:52):
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
(11:14):
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
(11:36):
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
(11:57):
the lights was undeniable. And with that, I mean not
just Christmas lights, I mean you're run of the mill
light bulbs now. Even in nineteen o 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
(12:21):
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
(12:41):
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
(13:03):
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
(13:23):
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
(13:44):
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
(14:06):
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.
(14:27):
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.
(14:49):
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 caught fire and
be 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
(15:11):
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
(15:32):
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
(15:53):
in front of his business would end up having trees
just draped in lights, and it became the first big
documented door 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
(16:13):
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
(16:35):
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 a concern about the possibility of
(16:56):
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 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
(17:16):
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
(17:42):
way too hot for aluminium trees. They also could potentially
create an electric shock hazard because aluminium can conduct electricity. Plus,
those aluminum 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
(18:03):
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 pains of colored plastic,
(18:24):
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,
(18:46):
the leading manufacturer of Christmas lights, it meant that there
was a drastic drop in Christmas lights sales as these
aluminum trees became all the rage. 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
(19:07):
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
rain of aluminum terror, the Christmas lights on the market
(19:27):
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
(19:47):
kind of cone shaped bulbs that I was talking about
the retro style. They're pretty big. Uh. 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 missed those. But
they drew a lot of power because a string of
fifty five what bulbs means that you're consuming two fifty
(20:08):
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
(20:31):
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
(20:51):
a really short memory, I guess. Anyway, the bulbs were popular,
and they were colorful, but they were also wasteful and expensive.
The many light would become a popular alternative to that bulky, hot,
expensive Christmas light of the past. The many lights are,
as the name implies, smaller. They only need two point
(21:12):
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
(21:33):
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
(21:54):
the behind the movement of electricity, and a volts supply
are 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
(22:16):
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.
(22:36):
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 sockets would mean
that each individual bulb would be slightly, maybe even in
(22:59):
per sceptibly 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
(23:21):
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
(23:44):
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 of the one
bulb that caused the problem. And often it would lead
to people chucking out a string entirely and just replacing
(24:07):
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,
(24:30):
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
(24:51):
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 a 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
(25:11):
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
(25:34):
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 one bulb were to go out, only
(25:57):
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
(26:18):
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,
(26:38):
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. This is important because
(27:01):
if the shunt had an equal or lower electrical resistance,
then the filament inside the lightbulb, the electricity would bypass
the bulb altogether and just go through the shunt. That
means you wouldn't have a string of Christmas lights insteaid.
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
(27:23):
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
(27:45):
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
(28:07):
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,
(28:28):
but the reduction in 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,
(28:50):
by mathematical definition, has to increase to make up the difference,
and an increase in current can become dangerous or even deadly.
Now but 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
(29:11):
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
(29:31):
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
(29:52):
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 will go
through the filament instead. Now, if the filament begins to
(30:15):
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
(30:37):
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 frustrating
is that some of the strings and lights are pretty
(30:58):
cheaply made, and the bulb 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
(31:19):
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
(31:43):
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
(32:06):
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
(32:27):
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
(32:48):
means Will can effectively type out messages by making individual
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
(33:10):
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
(33:32):
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 times was needed to make
(33:53):
sure all the letters that were being used were wired
up properly. You might have been able to get away
without wiring up a 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
(34:15):
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
(34:36):
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.
(34:58):
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,
(35:20):
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 am
I kidding? Still is? The line is, now, why the
(35:41):
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.
(36:03):
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
(36:24):
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.
(36:44):
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 of the filament, and since the electricity was
flowing through the strip, it means the electrical path is broken,
(37:06):
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,
(37:28):
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,
(37:51):
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.
(38:15):
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
(38:37):
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
(38:57):
in which the first fifty lights are blinking, than 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
(39:20):
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
(39:42):
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
(40:05):
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
(40:28):
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
(40:49):
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
(41:11):
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
(41:32):
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
(41:54):
used a very lightweight oil as the liquid, but more
modern versions tend to rely upon I 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
(42:19):
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
(42:40):
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 well 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
(43:03):
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
(43:26):
it's time for lights out. So that wraps up this
episode of tech Stuff. If you guys have any suggestions
for future episodes, reach out to me. You can send
me an email the addresses text stuff at how stuff
works dot com, or draw me a line on Facebook
or Twitter. The handle for both of those is text
Stuff h s W. You can also visit our website
(43:46):
that's tech stuff podcast dot com, where you'll find an
archive of how many episodes? Sorry? Oh all of them? Yeah,
all of the episodes is what Taria is saying. So
you can find all the episodes at tech stuff podcast Com.
You'll also find a link to our online store where
you can buy merchandise. And if you do, it's like
you're giving me a little Christmas present, because every purchase
(44:08):
you make goes to help the show, and we greatly
appreciate it, and I'll talk to you again really soon.
Hext Stuff is a production of I Heart Radio's How
Stuff Works. For more podcasts from my heart Radio, visit
the i heart Radio app, Apple Podcasts, or wherever you
listen to your favorite shows.
Welcome to Tech Stuff, a production of I Heart Radios
How Stuff Works. Hey there, and welcome to tech Stuff.
I'm your host, Jonathan Strickland. I'm an executive producer with
iHeart Radio and I love all things tech, And you know, guys,
I was trying to come up with a good idea
for a holiday themed show. In the past, I've done
(00:26):
episodes about some of the big tech items that landed
on holiday wish lists in the past, you know, like
the greatest tech gifts of all time. But I felt
like I've been there, I've done that, And besides, a
lot of those topics are like super timely and aren't
relevant from year to year, so it makes no sense
to ever listen to them after the year they published.
(00:46):
So instead of doing an episode that's going to be
irrelevant next year, I thought I would talk about Christmas
lights and how they work and why it was such
a pain in the neck to rig up special Christmas
lights for the Netflix series Stranger Things, which I've talked
about in a previous episode, but I figured it would
be a good point to return to in this one. Now,
(01:07):
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,
(01:27):
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
(01:49):
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 Quanza, 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
(02:12):
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.
(02:33):
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
(02:54):
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
(03:15):
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
(03:38):
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
(03:58):
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,
(04:19):
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,
(04:42):
and sugar. It's very food centricum. 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
(05:06):
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
(05:28):
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 leading 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.
(05:51):
UH Harvard professor named Charles Fallen, inspired by stories that
he had heard in Europe, did a lit up Christmas
tree 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
(06:12):
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
(06:33):
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
(06:54):
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
(07:18):
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
(07:38):
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
(08:00):
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
(08:21):
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,
(08:43):
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
(09:04):
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
(09:25):
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
(09:46):
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
(10:09):
terms was Benjamin Harrison, the grandson of our ninth President,
William Henry Harrison. Sorry, 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,
(10:31):
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
(10:52):
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
(11:14):
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
(11:36):
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
(11:57):
the lights was undeniable. And with that, I mean not
just Christmas lights, I mean you're run of the mill
light bulbs now. Even in nineteen o 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
(12:21):
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
(12:41):
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
(13:03):
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
(13:23):
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
(13:44):
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
(14:06):
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.
(14:27):
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.
(14:49):
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 caught fire and
be 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
(15:11):
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
(15:32):
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
(15:53):
in front of his business would end up having trees
just draped in lights, and it became the first big
documented door 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
(16:13):
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
(16:35):
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 a concern about the possibility of
(16:56):
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 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
(17:16):
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
(17:42):
way too hot for aluminium trees. They also could potentially
create an electric shock hazard because aluminium can conduct electricity. Plus,
those aluminum 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
(18:03):
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 pains of colored plastic,
(18:24):
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,
(18:46):
the leading manufacturer of Christmas lights, it meant that there
was a drastic drop in Christmas lights sales as these
aluminum trees became all the rage. 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
(19:07):
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
rain of aluminum terror, the Christmas lights on the market
(19:27):
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
(19:47):
kind of cone shaped bulbs that I was talking about
the retro style. They're pretty big. Uh. 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 missed those. But
they drew a lot of power because a string of
fifty five what bulbs means that you're consuming two fifty
(20:08):
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
(20:31):
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
(20:51):
a really short memory, I guess. Anyway, the bulbs were popular,
and they were colorful, but they were also wasteful and expensive.
The many light would become a popular alternative to that bulky, hot,
expensive Christmas light of the past. The many lights are,
as the name implies, smaller. They only need two point
(21:12):
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
(21:33):
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
(21:54):
the behind the movement of electricity, and a volts supply
are 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
(22:16):
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.
(22:36):
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 sockets would mean
that each individual bulb would be slightly, maybe even in
(22:59):
per sceptibly 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
(23:21):
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
(23:44):
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 of the one
bulb that caused the problem. And often it would lead
to people chucking out a string entirely and just replacing
(24:07):
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,
(24:30):
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
(24:51):
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 a 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
(25:11):
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
(25:34):
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 one bulb were to go out, only
(25:57):
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
(26:18):
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,
(26:38):
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. This is important because
(27:01):
if the shunt had an equal or lower electrical resistance,
then the filament inside the lightbulb, the electricity would bypass
the bulb altogether and just go through the shunt. That
means you wouldn't have a string of Christmas lights insteaid.
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
(27:23):
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
(27:45):
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
(28:07):
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,
(28:28):
but the reduction in 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,
(28:50):
by mathematical definition, has to increase to make up the difference,
and an increase in current can become dangerous or even deadly.
Now but 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
(29:11):
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
(29:31):
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
(29:52):
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 will go
through the filament instead. Now, if the filament begins to
(30:15):
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
(30:37):
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 frustrating
is that some of the strings and lights are pretty
(30:58):
cheaply made, and the bulb 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
(31:19):
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
(31:43):
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
(32:06):
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
(32:27):
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
(32:48):
means Will can effectively type out messages by making individual
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
(33:10):
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
(33:32):
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 times was needed to make
(33:53):
sure all the letters that were being used were wired
up properly. You might have been able to get away
without wiring up a 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
(34:15):
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
(34:36):
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.
(34:58):
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,
(35:20):
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 am
I kidding? Still is? The line is, now, why the
(35:41):
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.
(36:03):
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
(36:24):
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.
(36:44):
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 of the filament, and since the electricity was
flowing through the strip, it means the electrical path is broken,
(37:06):
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,
(37:28):
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,
(37:51):
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.
(38:15):
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
(38:37):
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
(38:57):
in which the first fifty lights are blinking, than 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
(39:20):
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
(39:42):
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
(40:05):
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
(40:28):
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
(40:49):
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
(41:11):
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
(41:32):
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
(41:54):
used a very lightweight oil as the liquid, but more
modern versions tend to rely upon I 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
(42:19):
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
(42:40):
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 well 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
(43:03):
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
(43:26):
it's time for lights out. So that wraps up this
episode of tech Stuff. If you guys have any suggestions
for future episodes, reach out to me. You can send
me an email the addresses text stuff at how stuff
works dot com, or draw me a line on Facebook
or Twitter. The handle for both of those is text
Stuff h s W. You can also visit our website
(43:46):
that's tech stuff podcast dot com, where you'll find an
archive of how many episodes? Sorry? Oh all of them? Yeah,
all of the episodes is what Taria is saying. So
you can find all the episodes at tech stuff podcast Com.
You'll also find a link to our online store where
you can buy merchandise. And if you do, it's like
you're giving me a little Christmas present, because every purchase
(44:08):
you make goes to help the show, and we greatly
appreciate it, and I'll talk to you again really soon.
Hext Stuff is a production of I Heart Radio's How
Stuff Works. For more podcasts from my heart Radio, visit
the i heart Radio app, Apple Podcasts, or wherever you
listen to your favorite shows.
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