Teardown of an LED Traffic Light Module 

Another advantage of coloured LED is like your green it has no colour when off and just lit by the sun. That way you can't accidentally mistake which light is on.

As to the green one not having a green lens - that is extremely common in my city. The red and yellow have red and yellow lenses, but the green one has a clear lens. *(For LED-upgraded intersections.) The best reasoning I can come up with is that way if you have the sun behind you reflecting off, you won't accidentally see the green one reflecting the sun, and think it's lit. You will only see the color green if it is actually illuminated green. Reflections on the red and yellow may make you think they're lit red or yellow - which is a fail-safe condition. "Oh, shoot, I can't tell if that's a red light or a yellow light!" Either way, you stop. You don't want a fail condition to make people think it's green when it isn't.

I immediately got the ''Big Clive'' deja-vu as soon as you've switched to the top view camera.

I love the gag of having a CFL as this channel's icon.

Big Clive would be proud.

Nice teardown! It's worth mentioning that in some cases, each light will have more than a 50% duty cycle. Many lights at intersections between large and small roads remain in one state until the presence detectors notice a car on the smaller road, and then switch over. This is also true at some pedestrian-only intersections where the light is controlled solely by the pedestrian switches.

Great job on the video! Was definitely getting some BigClive vibes during the brute-force destruction with a screwdriver, just missed the common phase "Other things worthy of note...". I like the idea of this second channel for deeper dives into the tech with a sort of informal approach.

The LED board was made in the 36th week of 2008. You can see the date code on 10:37, right under the LUMILEDS brand. The power supply board was made maybe in the 21st week of 2004, as seen on that code on the right top side of the board at 10:37 as well, but you'll have to check the ICs on the board and see their date codes to be sure about that. (Every 4 digit date code is written in the following format: WEEK/YEAR, as in the LEDs board, 3608 (36th week of 2008), other example would be 3691(something that was made in the 36th week of 1991)).

Love these kinds of videos. As a little kid I always wanted my own stop light. My parents got me one of those Spencer Gifts novelty ones for my bedroom that used Christmas tree bulbs. As I got older, I realized how huge they are when they aren't hanging 18 ft up in the air.

You definitely need to contact Big Clive! He'd love this :D It's a massive difference to the regular LED drivers he usually looks at, too :O Email him! :P

The LED traffic light I took apart a while back (11 years?) had a nearly full diameter layout of LEDs, about the size of the first dimpled diffuser you removed. Most likely like the type in the other video where some of the LEDs had failed. I was surprised to see such a small array of LEDs in there! Lumileds was a joint venture between Agilent (HP) and Phillips Lightning. They had their hands into almost anything LED. My dad used to work there as a technician cutting, doping, & inspecting wafers for the dies. Phillips bought out Agilent's interests, and moved production overseas and nearly everyone at their Silicon Valley location, shy of pencil pushers, began counters, and cubicle chattels got handed a pink participation prize.

You may not be Big Clive, but this video amused me and also made me think - wow, is that it?! Thanks!

FWIW, the capacitor looks to be the distinctive brown of Nichicon’s 105°C range. And that’s basically exactly the cap you’d expect to see in an application like this one.

Nice teardown. I love seeing inside items like this, that I wouldn't easily be able to access myself. Some other things you might consider pointing out in the future: ·Capacitor brands - are they crappy, or name-brand (nippon chemicon, rubicon, etc.) ·Date codes on chips - how old are the parts? ·Chip part number "for those playing along at home" (point out common chips like 74 logic, op amps, microcontrollers, etc.) ·Relay specs and branding - are they crappy, or name-brand (omron, schneider, panasonic, etc.) ·Fuse ratings and types (basic glass fuses, high rupture capacity fuses) ·Measure voltages and currents if you have a multimeter (how much power do those LEDs use? Are they in series/parallel combinations?) ·If you have an oscilloscope, you can probe signals in different parts of the circuit (doesn't apply too much for this teardown though)

I insta-subscribed to this channel as soon as I was done watching your stop light video. Your content is top notch. Keep up the awesome work!

Hah, just as I was thinking ‘someone send Clive one!’ you made the same reference. Kudos, and good luck on chan 2. :) but ow that buzzing hurts so much.

Happy to see a second channel for more in-depth teardowns of items. yes you are no bigclive but as this is only your first teardown video and bigclive has had years of on the job experience (as that he is an electrician by trade and quite often works for theater companies) you did a fine job. Your knowledge will grow with the more you do.

The power supply is constant current, which unfortunately is more complicated than constant voltage. I agree it looks well made. It has to keep the LEDs within brightness spec across a very wide temperature range.

This is interesting. I had some LED traffic lights from here in NZ (current generation ones that are being installed) and they have a massive array of regular high brightness LEDs, shining through small lenses to focus the beam in a smoother pattern (basically just a solid level of intensity). Some of the older date codes were running 5mm through hole LEDs, and the newer ones used an array of small SMD packages with an integrated lens. 250mW rated IIRC. They were crazily complex compared to the electronics in this too. Running 8 separate series strings if i remember right, all with current controlled drivers. Construction was a single large round driver PCB, and in front an aluminium/FR4 hybrid or a regular pcb with the through hole led ones. There was a lens assembly with separate individual lenses for each LED in front. All in all, it was an interesting thing to take apart. Mine were screwed together with a plastic "cup" for the lens, and a cap that sealed onto the back with a silicone o-ring. The weird part is, despite being super overbuilt and very modular, they get replaced and ditched, even when the issue with them is as simple as a blown fuse (which all of mine were) Obviously it was built as a high reliability unit, but it was truly gilding the lily even in that domain of electronic design. I suspect a very lucrative cost plus style contract or something, where the EE responsible got a chance to just go hog wild with the design :D Anyway, thought you'd enjoy hearing about the differences with lights down under, and keep up the great videos man!

You are very detailed and interesting...I have loved traffic lights, streetlights RR crossing lights and most street furniture since I can remember, looking back as a child riding in the back seat of my Dads car always looking at the different traffic light configurations, lenses, shades, etc. and being so fascinated. Funny how that LED driver/power supply has 2-glass fuses, not really a serviceable component in a sealed fixture. Love the tech talk and traffic engineering talks, great info, keep un the great work!

This is a pretty interesting video; I'm enjoying the more hands-on, in-depth feel. I was just thinking there was something big-clive-y about this video as you mentioned him!

Not gonna lie, I was expecting it to be one big circuit board with a huge grid of LED modules. Not this 8 LED modules madness!

I would also like to mention there's a arrow marking on the back for the installer to position it right. It's there for the refractile grid because it has a rotation bias. The lens emits a horizontal beam when installed correctly to maximize the viewing angle on the ground.

WOW, that lens is amazing. And just think that because they're plastic they can be manufactured so cheaply.Augustin-Jean Fresnel would be so proud.

I've always been curious about the insides of these too, thanks for showing! I'm another person saying that I do think they are a full set, the green LED lenses here are clear as well. So no worries about that!

You were right on with GELcore. "They make high-brightness LEDs used in traffic signals, signs, and automotive applications. *GELcore is a joint-venture* *between General Electric Company* *and EMCORE* *Corporation.* "

I laughed pretty hard when you got to the guts there. Expected a few more LED's than that.

That's a cool power pack, great for testing and whatnot. Thanks for taking that apart, I wanted to see inside one of those style lights too. My town has a lot of the older ones with tons of the domed through hole led's on a board, but we got some of these at new intersections.

Great video! If you wanted to adapt the modules for decoration use indoors, you could probably swap the driver for one of those cheap eBay 1W drivers to make it a lot dimmer.

It was really cool seeing the inside of that. I purchased an old traffic signal from our lighting control company a few blocks away from our shop and wired up to work in my train room with a controller that changes the signal just like a normal traffic signal. I didn't want to take my depart, but I've always wondered what the inside of those LED modules look like.

Oh, another Big Clive viewer :)

Don't ever compare yourself to others! I watch both of you and love both! Your skills are on point with him!

I really want big clive to do a tear down now. That is a really complex board just for driving LEDs. There's also a 2 pin connector between the power terminals, so clearly the unit is designed to more that just be on or off on the supply.

The optics remind me of the backlight diffuser seen in most common LCD backlights. I have one of those 115v capable power banks! They are, as you say, cool. Yay fellow BigClive fan!

I thoroughly enjoyed the informal, Big Clive-ish tear down!

Nice to see not designed as disposable (as initially thought they were sealed) but designed for quick repair of the supply or led (probable replace in field and repair in shop).

As soon as you started to pry open the top lens I thought to myself.... if only he had a spudger like big Clive 😁

I also recall technology I first saw in my native California at least 40 years ago: Fresnel lenses. These used conventional bulbs (obviously, in that era) but had a colored Fresnel lens over them, restricting the view of the signal unless you were facing it directly. This was supposedly to keep opposing traffic from jumping the gun by watching the other signals and entering crossing traffic. I suppose they are still around, but I've seen fewer of them lately; most cities now simply add a delay... the opposing signal will go red, but you won't get a green for about 3 seconds.

I've seen every video on your main channel and I'll be catching everyone on this channel :) love the less-edited style and hearing you speak in a more 'conversation' style. Looking forward to more of your content

The LED-panel is pretty much a standard-off-the shelf product. i have the same kind of modules, just as circular rings with lenses mounted.

I liked this video especially when you showed us your hands. This is seriously a compliment and not meant to be weird even though it’s going to sound it, but you have really, really pretty hands. You should be a hand model. Thanks for showing us the inside of the led green light.

I dug the tear down, I'd be interested to see more of these in the future. Subbed, and looking forward to more from this channel as well :)

That's quite fun. I was thinking "Big Clive" would love to take this apart - but you said it yourself. Already love your new channel. Liked and subscribed.

Complete shot in the dark here, but my guess as to why the yellow light needs more energy would be perceived brightness and the filter used. I'm guessing that our eyes pick up green and red light better, so we need more yellow light produced to see an equivalent brightness. Also, the yellow filter may absorb more of the spectrum put out from the LED then the red filter.

It's incredible how big those are when not far away from you.

6:49 although you were trying to hide that you started to unscrew the screws while the lamp was still plugged in your power-bank, I saw it 😂

I am a traffic signal technician for the state of Texas. Every single signal in the state, with extremely few exceptions is using LEDs. I work in the top 20 counties, and only know of one. If you wish to deepen your knowledge about “everything” federal traffic related, including signal look at the MUTCD , manual in uniform traffic control devices. It of course includes a section on signals. I’ve enjoyed your last couple of videos. Thanks

Love this! Please take more things apart! :)

If this were a Big Clive video, the video would end with a nice warm white LED traffic light.

UK has coloured lenses with white LED behind... The green ones in UK look interesting because the coloured lense looks blue when it's off

Hi, I am guessing that the one you took apart is a newer design with fewer, but brighter LEDs? My NC city put in the large array type 10 or so years ago. Maybe 15. They started getting failed LEDs a few years later, but still functioned. Though with dead LEDs they looked like a bad 8 bit video game.

I was actually expecting way more LEDs to be in there than that. Thanks for the teardown.

Here in Australia, there's a sort of quirk in the law where it is *technically* illegal to replace a 240v light bulb, because, in a way, you are manipulating electrical systems, or something to that effect. So traffic lights here have a clever little workaround, so that you don't need to be an electrician (or 'sparky' here) to replace the bulbs. What they do, is they feed 240v to the light bulb box, but behind each light, there is a stepdown, likely isolation, transformer, that turns 240v into 10v, IIRC. So the lights here are all 10VAC, and to that end, I guess that LED retrofits may leave this transformer in place, but have interesting power supplies that would convert 10V into whatever DC the LEDs need. Also, I live in Queensland, but traffic lights in New South Wales and Victoria are *mostly* the same. So I was taken aback when I noticed the LEDs in Tasmania (of which there are very few, most are still incandescent!) looked markedly different. It took a solid couple of days to figure out, and a lot of distracted driving gawking at the goddamn traffic lights, but what they'd done In Van Diemens Land, is they don't use the fresnel lenses. Now the fresnel lenses here along the east coast, aren't to the extent in the states where they mimic incandescent bulbs. You will still readily see each LED, but the lenses are a lot less... aggressive, for want of a better word. The lenses they have, only just diffuse the light a little bit, and spread it out more. So yeah, that's a bit of traffic light trivia that no one will care about, and that Mr Technology Connections will probably not see!

1:00 I wouldn't assume it's from another set, i've seen a few traffic lights that have coloured plastic for red and yellow but clear plastic for the green. No idea why they do that. Edit: thinking a bit, maybe it's to make it extra clear when the green light is not on if you just can't see any green at all?

Great second channel! Big Clive is probably proud of you!

Like for Bigclive reference

I don't know, I was seriously impressed when you opened it up, just those 8 LEDs are all it takes?! Optics for the win!

Never thought that Ross Matthews would get me so interested in traffic lights

Please post another video if Big Clive decides to take a look at one of these for you!!

I was surprised at how many components were on that circuit board. As a regular Big Clive viewer, I expected it to be just a bridge rectifier, a couple of caps, and a transformer.

I chuckled a little when I saw that the avatar for this channel is a CFL.

I wouldn't exactly call it ruining the stop light, unless you plan on running it outdoors in weather. It'll all go back together with the outer rubber gasket holding the sandwich of layers. Even if used outdoors after this, you could easily use some RTV/gasket maker on the inner edge. Also, if you re-assemble it, but leave out the diffuser lens but leave the Fresnel lens, it creates a very smooth, even glow that can be nice for some applications..

Now I want to be like Mr. Rogers, and have an operational traffic light hanging on my wall for no reason.

The "prismatic" lens is a microlens array or homogenizer, and it does more than just look incandescent. When the 8 sources are focused through the Fresnel, the light is collimated (mostly directed out in a fairly narrow beam), but there is still a distinct image of 8 LEDs. You can see this when the camera points at the ceiling. The homogenizer turns the large image of 8 LEDs into hundreds of tiny overlapping images of 8 LEDs. The reason it "looks incandescent" is that incandescent bulbs need the same thing. The parabolic reflector behind the bulb makes most of the light come out the front, but it still has an imaging problem--a bright spot direct from the filament, and a halo from the reflector. The homogenizer changes this to hundreds of tiny overlapping images of a spot and halo.

For what it's worth, I think I actually *preferred* the switch to the camera mic. Your lav mic was sounding awfully rumbly. Perhaps it might benefit from a little highpassing? (Or maybe something something positioning?)

4:46 Knew would be able to open w/o breaking outer “shell” with screwdriver (what I prefer using are nylon “plastic” car clip/panel removal tools for things like this, as helps to not chip, crack…..damage anything while taking a peak. Or at least mitigating damage if does happen) as have repaired some old incandescent ones in my electronics repair business long ago. What I didn’t know about these new LED ones is how few LEDs are actually inside. Thought for sure would have 16-22; wasn’t expecting to see just 8….COOL! Thx again for making info/learning FUN & COOL (if only you were my science teacher decades ago when in school; wouldn’t have been sleeping and bored during class😉) ✌🏻✌🏻

If you asked 100 people how large are traffic lamps. 99+ would say smaller than they are. I remember looking at a fallen pole and being impressed at the size of the thing. It's a great example of perception vs reality. Only 8 leds? Wow. White led tech advanced overnight.

That's incredible, I never would have guessed it was just 8 LEDs magnified through a massive 1-foot diameter lens.

I like the old style that was filled with all 5mm LEDs.

I was just thinking you should send it to Big Clive as you said his name.

Please do send one of these to Big Clive. Im sure he'd have some intersting things to say about it. Looks very well made. Lumiled & Luxeon are trademarks of Philips. So these are Philips power LED chips. Looks like they made the LED array PCB as well. Probably specifically to order for the company that put these traffic light modules together.

You gotta give us a link to that powerpack (if you'd recommend it)!

The power supply board is just that. It takes your 120VAC source, steps it down with the transformer to most likely to a voltage a bit over 12VAC. From there it goes to the four diodes and a couple of resistors to be dropped to and converted to 12VDC. The rest of the components on the thing are all control circuitry to smooth out the DC power to as consistent of a voltage as possible, supply a load resistance for the LED board, and to eliminate flicker as flickering will destroy the filament in the LED. Given the color of the LEDs, it would be very safe to assume that the maker did know the application that the LED board was going to be used in. The application would be a basic part of the design spec given to the part supplier so they can build a part that would meet a minimum reliability requirement.

So, I'm using headphones at the moment, and each time the video cuts to sped up video with the sped up audio I have this eerie feeling that my head is submerged in water. Tripy!

I think the LED boards are purpose-made because the light wavelengths need to be really precise to meet standards (and the blueish-green is a pretty unusual color I think)

I noticed that pigeons would huddle in the old incandescent traffic lights in cool weather. But not since LEDs came to town.

That beer can shaped battery pack inverter thing is noisy but cool. How long does it last before needing to be recharged?

I've taken quite a few of those GE Traffic Signal inserts apart. I'm glad you did not cut it open. They have a power supply with a output of 24VDC. The power supply can be repurposed into other electronic projects or used to repair other lights. The screw that holds the wire cover has kind of a dual function. it not only hold on the cover but when assembling the light it allows the air trapped inside to escape. Also I have found some that where full of water from being stored improperly so the seal is not 100%.

still wanna see what is inside the red one

That LED module will have been manufactured specifically for a traffic light; the NTSB (or one of them agencies) specifies the allowed color range for traffic signal colors, so the module has to fall w/in that range, which is on the blue side of green (where standard LED green is a bit on the yellow side) and is an inconvenient color to create with LEDs.

Figured it be simple. But funny as you said you would use a Dremel, I was thinking, ugh just Start with prying, and you did, well done. :)

I saw a dumped old style console flatscreen TV behind one of the stores rotting in the rain. I pulled the tinted screen off and wala a massive flexible Fresnel lens "30"x 40". In normal sun it will burn instantly any thing I focus it on. So those things are a sweet item to have. Little history that maybe you would like as a video. I do believe they where originally invented for lighthouse use to focus the meager light into a more intense beam making it visible from long ways. So logically this would be applied to traffic lights.

Wow, that was a lot fewer LED's than I was imagining! I got a little nervous when you started working with the innards with your screwdriver while it was still plugged into your power supply, but you seemed to correct that quickly before taking the bits out.

I'm the guy that changes these things out.

I believe green LEDs with clear lenses are starting to become more and more commonplace. The general idea is so they don't get mistaken for a green when the sun hits them, to prevent drivers from blindly proceeding into an intersection when they aren't supposed to. They do throw off the look of a traffic light when they're powered off though, especially if you're a collector.

Foolish me, here I thought all those dots were individual LEDs... That's what I like about engineering. The simplest solution isn't always the most obvious.

Definitely deserves a link up with Big Clive :)

The LED signal bulb I have is much thinner than yours and has many more than 8 LEDs on it. I can even see which capacitor blew on it's circuit board should I want to replace it.

That's interesting and makes alot more sense. I remember about a decade ago when they started converting to LED traffic lights, then all of a sudden more recently, they started looking like the old incandescent ones again. They used to be about (idk exact #s) but like a 60x60 array of 'dot matrix' circular arrays of small LED's that covered the entire surface of the bulb area. Now I see in this video they went to more condensed and only 8 of them and artificially diffusing and magnifying them (similar to an incandescent). Why is that?? Doesn't that eliminate one of the advantages of the original LED matrix bulbs - which was equal spread of brightness across the surface? And what about graphics such as an arrow for a turn signal? Used to be, the LED's were simply arranged in the shape of the arrow, like pixels, and that used much less number of individual LED's. Now I'm assuming they went back to some sort of filter that is shaped like an arrow, again why? The original LED's seem and look better, in my opinion.

I don't know "Big Clive", but that is a high efficiency switching power supply and controller you are referencing at 9:50. Similar to what is powering your computer. LED's don't generally like seeing large potentials (voltages) and will last much longer with steady controlled power. There will also be some logics on the power supply to keep things from going "Pop!". Odd thing is, I don't see a full wave bridge rectifier on there, which would help to explaing the unusual amount of noise coming from your square wave portable inverter. Sweet gadget by the way.

In regards to the heat synch not having thermal paste, it wouldn’t need any to keep it cool. They probably wouldn’t get hot enough on the led board to need it. Cpus require it cause of the extremely high temps they get, they need more uniform and efficient cooling that the thermal paste provides.

Exactly what I expected... except I expected more LED's. The real hero here is the fresnel + prismatic lens combo.

I was just thinking that this was Big Clives's territory, and then you said it!

I'll take a shot at some of the questions raised by this video. (BigClive fan) This is a full switchmode power supply, and it is arguably over engineered for a lighting circuit. They haven't gone cheap on this. There are ways to do this very cheaply, but it would almost certainly compromise efficiency and reliability. You might have got this for ten bucks, but I'm betting GE sell them for much more than that, maybe ten times more. The buzzing coming from the power supply when you run it off the powerbank/inverter is most probably because the inverter is outputting a square wave. It's much cheaper to just make it a square wave output than it is to synthesize a sine wave. The buzzing noise is some of the high voltage components not being very happy about the square wave. It's low frequency, so it's definitely on the 60/120Hz side of things. (120 Hz because that's the overall frequency of rectified 60Hz power). It's not a "120V power supply". That's just the input voltage, which usually goes without saying in whatever country you are in. We normally describe power supplies by the output voltage, which would tell us a lot more about the application and how it is used. You missed an opportunity here to measure the output voltage which would tell us a lot about how the LEDs are being used. If I was designing this I would put all the LEDs in parallel, because LEDs normally fail open circuit, so a failure in any one LED would not take out any of the others. That would mean that the output of the power supply would need to be between 3.0 and 3.2 volts depending on how hard you want to drive the Luxeon LEDs. 16 watts (for example) at 3.2 volts would be five amps, which means that is quite a power supply. The reason they use coloured lenses over the red and amber lights, is because LEDs with longer wavelengths have much lower light output. It's much more efficient to use white LEDs and put a coloured lens over the top. Green LEDs can be made with similar light output compared to white LEDs with a coloured lens, so you probably save some money on being able to use a clear lens. The only real difference between the Luxeon white and green LEDs is the type of phosphor used - the driven semiconductor is the same. You were exactly right about the heat sink - there's no other reason to put a large aluminium plate behind the LED circuit board. You'll notice that the LED circuit board is on an aluminium substrate for the same reason. I don't know why they didn't use heatsink compound, but I'll bet that those lights are not designed to be on constantly. They will have at best a 50% duty cycle with a maximum on time of only one minute (maybe two). This problem will be mostly because the whole thing is inside a plastic enclosure with no ventilation. If left on for long periods either the LEDs will fail or the plastic shell will start to deform.

If you cursed a lot more I'd be getting an ave vibe.

Wouldn't have thought a small switchmode PSU would take too kindly to being flashed on and off repeatedly, still, a necessary evil if you're manufacturing these things as a direct swap-out replacement for oldschool lamps I suppose. I'm guessing that a brand new traffic light installation would do away with the separate PSUs and feed the lights with the low voltage DC that the LEDs use, would be a lot more reliable I'd have thought.

That 3608 on the LED board looks like the date code. If it is, that board was manufactured during the 36th week of 2008.

judging from the tabs on the clear cover and the longer slots in the back piece I believe these twist off

Youre the only channel that I have notifications turnt on for.

GELcore L.L.C. designs and manufactures a full line of discrete, high-brightness LED's (Light Emitting Diodes). The Company's LED's are used in traffic signals, signs, displays, and specialty automotive applications. GELcore is a joint- venture between General Electric Company and EMCORE Corporation. (from Bloomberg's website)