Photoelectric light controls are weirder than they seem

[@Demonrifts]

I don't know what kind of magic Alec uses, but the fact that he releases videos on topics that I really couldn't care less about, and that I watch them, is a testament to something I suppose. He finds a way to make things that are rather irrelevant to me interesting, and I rarely pass up the opportunity to watch a Technology Connections video. EDIT: Wow. KZbin is really bad at notifying you for activity on comments. Last time I got a notification for this, I had a few replies and a handful of likes. Cool to see a lot of people seem to agree with me.

[@drumset09]

Usually the magic of buying two

[@TonyP9279]

@@drumset09 Somewhere there is a streetlight that is oddly missing a sensor and a bulb.

[@Dargonhuman]

@@TonyP9279 It's probably the one at the end of my street that hasn't worked right since I moved in and all calls to the city have gone unanswered...

[@tanya5322]

His videos are curiously entertaining and educational. His voice is generally calming. And the detail he gives during explanations are usually so good that I can visualize what’s happening even though my eyes are closed and I’m using the video as a bedtime story 👍🏽😉 There is even more edu-tainment if you actually *watch* the video. Especially if watching with captions. 😊

[@OutOnALimb9199]

anything is interesting if the presenter is interested. That’s what I think :)

[@w49660]

The little bit of heat they create probably helps melt snow off them in the winter, keeping the light from being on all the time because the sensor is covered up. Like how stoplights had to add heaters when the went to LEDs.

[@K-o-R]

*_BUT SOMETIMES!_*

[@soundspark]

Although don't traffic light heaters only operate when it is snowing and thus still end up using less power than incandescent?

[@aculleon2901]

​@@soundsparkEven when heating the snow away it probably uses the same if not less power.

[@LillyP-xs5qe]

Or we have heaters as option to more efficient ones to turn on during snowy days, and you can control it with a tiny LED and a fibre optic, if snow can reflect the light to a light sensor, heater go on, no snow, light isn't reflected, no heater

[@AtlasReburdened]

​@@LillyP-xs5qeNo need for even that much complexity. There are transistor output thermal sensors packaged in TO-92 that come with factory calibrated thresholds that can serve the same role as the LDR, but for temperature. This would just kick a heater on when the temperature goes low enough, which would obviously be a bit less efficient than controls that need actual snow to activate, but it would work and it would bypass the need for fiddly fiber optics, the chance of unskilled assemblers screwing up placement and alignment, the addition components to read and react to the level of reflected light, and the need for the clever physical engineering required to make sure that snow falling with any vecor activates the sensor.

[@johnwiley8417]

17:15 This device is much more tolerant to lightning, too. Important when it's setting atop a tall, grounded metal spike.

[@LillyP-xs5qe]

I mean if that is a worry, give it a Faraday cage, problem solved

[@naverilllang]

I doubt it would survive a lightning strike. Even if it did, plenty else in the street lamp wouldn't. Including the lamp itself.

[@AtlasReburdened]

Source?

[@davidfernelz]

@@LillyP-xs5qe that ads more cost, complexity, and points of failure. It can be easy to solve a lot of the problems that can arise when engineering something, but its very difficult to do it in a simple, cost effective manner that increases longevity. there is a reason why "over engineered" is a common phrase.

[@robertlapointe4093]

Funny you should say that. The last time I saw the insides of one of these controllers was when it had just been turned into plasma by a lightning strike. I was stopped at a red light and was across the street at the time, about 50 feet away.

[@edcrypt]

We had a little craze here in Brazil in the late 90's, where kids would use laser pointers to turn off streetlights. Sometimes a single lamp would turn off, other times a whole block or more would go dark. Good times.

[@moos5221]

that sounds like something i should try. but then again...i have a key to open the street lamps and could just turn them off forever. :D

[@solsol1624]

While I don't approve of this, it is ingenious!

[@AlexandruLipan]

​@@moos5221Where I live there is a side road with the new led illumination and someone rotated the streetlight to use it as a free illumination for his garden, where originally was illuminating a corner with a wall. Not even a week after, a car slammed on the wall that was now in complete darkness.

[@naumen6508]

​@AlexandruLipan This made me chuckle. Hopefully the person is fine. Why would you illuminate your garden like that in the first place...

[@Moto_Medics]

@@naumen6508 A lot of street lights are metal halide if blueish looking or high pressure sodium if orangey spectrum and are crankin out +/-1000 watts, those are the same bulbs used to grow the sweet sweet devils lettuce among other regular lettuces. The distance probably isn’t ideal but would be enough to keep ‘em growin overnight if close-ish I’d wager.

[@BixbyConsequence]

Always a joy. After a 45+ year career in IT, I love how you elegantly summarized the challenges of software in a few seconds. Spot on, LOL

[@blaknoizee]

The software issue was amazing hahahhahahhaa

[@rlin]

undoubtedly a dig at adobe premiere 😆

[@vigilantcosmicpenguin8721]

@@blaknoizee A picture is worth a thousand words.

[@michaelcalvin42]

To be fair, the software required to control this particular application would be very simple and easy to verify correctness / test. But as others have said, a microcontroller-based solution would suffer from other issues which this design avoids entirely, and the circuit design would need to be proportionally more complex/expensive to compensate. If it ain't broke, don't fix it.

[@dr_jaymz]

@@michaelcalvin42 new installations are micro-controller based and this allows for load shedding and features like turning every other light off after midnight, dimming and other such features. They can even tell if any have failed and wait until that meets a threshold before they send a man with a pole out to smack it. I would imagine such features would be mandatory if they are not already especially in the EU. North America tends no to bother with that nonsense (for now). You don't need to worry too much about the MCU having issues because the LED fixtures fail much well before!

[@frogandspanner]

Here in UK, when I was young in the ('50s and early '60s) street lights had simple timer switches, not controllable over the supply. I discovered that the ring magnets from old B&W TV sets could be used to switch the lights on or off by swiping the magnet across the metal access panel. What really happened is that the switch phase was changed, so when the light should be off it was on, and vice versa, and it required a visit from a person to reset the phase.

[@danb9447]

anarchy in the UK

[@frogandspanner]

@@danb9447 It was scientific experimentation. Honest!

[@BlueTangWebSystems]

Back in the 70s as a kid I 'err, rescued' one 'hanging out of a lamppost' and used it to switch the Xmas lights on and off. Turns out they are quite sophisticated and can automatically adjust for BST and the sunset / sunrise time.

[@EwanMarshall]

Some still use timers, not so simple ones though :D. For example the lights here go out again about 1am for the remainder of the night.

[@frogandspanner]

@@EwanMarshall The timers were usually set to switch off at 10:30 in Leeds, after which time it was pitch black.

[@callynd]

I work at a hardware store. This video has taught me how one of the products we sell works. This isn't the first time you've done so, but it's the most direct time you've done so and I want you to know I appreciate it. Your videos on regular switches and thermostats and LED bulbs are probably more important, but this one is illuminating in a way I had no idea it could be.

[@kyx5631]

Illuminating, you say...

[@TheOccupants]

LIKE LIGHT!

[@arthurmoore9488]

Take a look at one of BigClive's teardowns of a circuit breaker. One of the tripping mechanisms is literally a heater and a bimetalic switch. It gets hot and stops before the insulation in your walls starts to burn. Almost the exact same mechanism as shown in that box sensor is all over the place!

[@death03125880]

When I was working as an electrician and was keeping street lights in shape, I was quite often dealing with those sensors. And contactors they control. We used to call those photo resistors as "the eyes". It's quite the feel when you cover those and you hear that loud *clack*

[@bublgumclaymore]

If you happen to be working inside one of them when you hear the click I would probably ruin my white pants

[@death03125880]

@@bublgumclaymore well, you'd be too far in such a case to hear that clack

[@BillAnt]

The beauty of this simple photo switch is in the "eye" of the beholder. ;)

[@alanhilder1883]

That loud clack, for me was in a cabinet of many contactors. You want scary, try a liquid resistor starter. ( motor starters ). 3 tanks of "dirty water", looks like big batteries, that when that first loud clack happens, it is completely drowned out by the electric arc sound from those tanks complete with bright flashing lights. When the 2nd stage kicks in it goes quiet but those tanks are still connected to the power, don't drop your spanner etc, they will bite.

[@jillwoodral3518]

It's back!! The painfully smooth jazz, the patrons, bloopers, funny closed captioning joke at the end. I live for that at the end. My boyfriend introduced me to your channel a couple of years ago, and when you have a new episode, we get excited and wait until we are together to watch it like a little date. He's a mechanical engineer, and I'm just a lady who enjoys good puns and having my mind blown by things I never knew. I really enjoyed the toaster episode.

[@Junimeek]

aw thats adorable, hope things always go that well for y'all

[@keard558]

What's even more crazy to me is that he doesn't even have any formal engineering background, it's all self taught!

[@unemployedgringo]

Wow, this is my dream relationship 😢 I always wanted my ex gf to watch these with me but she'd always get bored after a couple minutes

[@keard558]

@@unemployedgringo you'll find your queen someday king

[@AdhamOhm]

As a kid, I discovered that if I took a small mirror and held it up against a light-sensing nightlight, angling it so that the light from the bulb would be reflected to the photoresistor, the nightlight would go into a feedback loop and start flickering like a strobe light.

[@audvidgeek]

I ended up with an outdoor light that did similar. I installed a screw-win dusk to dawn sensor in the lamp. The photoresistor was catching a reflection off the shiny lamp housing and was causing the light to cycle on and off

[@BillAnt]

That's how Disco lights were Disco-vered. ;D

[@mjm2203]

I was able to do that with just my hand, it was fun.

[@ArkhamHedler]

Laser too

[@TimurTripp2]

I remember doing that feedback loop thing with an outdoor holiday light sensor to make a strobe light effect. Unsurprisingly letting that go a while killed it.

[@Xeonerable]

I never knew how simple these devices are but just how well they do their job. This is one of my favorite educational channels.

[@Prophes0r]

Remember that simple in execution doesn't always mean simple in design/creation/implementation. There are plenty of "simple" things that we don't realize we can apply to solve complicated problems for a LONG time, because it takes a through understanding of something, plus a bit of creativity, to apply it. Take the FFT. It's not doing anything 'new'. But realizing we could use it to VASTLY simplify some things was evolutionary.

[@2ndfloorsongs]

​@@Prophes0rIf an FFT isn't doing anything new, then there truly is nothing new under the sun.

[@WaffleAbuser]

And most of the time, they do their job so well that you don’t even realize how well they do it.

[@timsmith2525]

Right? Seems like something that should be taught in high school. It amazes me how so many useful things can be done by pushing electrons around.

[@NemoForever338]

I've been watching your content for at least a year, and became an electrician along the way. I'm thrilled that your content is not only still amusing, but actually useful to my work. Cheers, and thanks for making it

[@BillAnt]

This was a great example of a simple thyristor switch in a real world application. They also have large ones which can handle much higher power loads, but I guess a limit switch will do just fine.

[@ActuallyDarcy]

I'm also an electrician and these videos helped me a lot during my apprenticeship. I'm confident with maths and logic but I struggle with concepts, his videos on switches and all types of electrical components really helped me grasp what was going on. Hell, I'm qualified now and even this video taught me something, I put in sunset switches pretty regularly and I've never thought to look into how they work

[@kaleidocore]

In the 80's we only had a single one of those at a central junction box, controlling all the street lights for miles around. We kids back then would sneak there in the dark, climb up and put a flashlight over it. This was particularly fun during the dark fall and winter season, of course. Thinking back it seems strange how this sensor was not covered in disabling snow and ice, but maybe the heat from that thermo switch was less of a quirk and more of a critical feature...

[@Moto_Medics]

Holy cow that’s genius, my vote is your 100% correct I was thinking what a strange waste of power but now it makes way more sense for cold climates.

[@thegamerfromjuipiter7545]

@@Moto_MedicsSame principle as the traffic lights covered in another video on this channel I suppose. (The switch to LED traffic lights meant they no longer melted snow off without adding an additional heating element).

[@Septimius]

While explaining how the mechanism delays turning on the street light, I'm sitting here thinking "This is a really clever hysteresis. I really hope he explains that it is" "Some people would like me to say the word 'hysteresis'. You're welcome!" - I've never felt so cared for and shouted out before

[@Vacuon]

I worked at GE for Lightgrid V2, that was funny to see something I know so well on this channel (amazing work btw!). I just wanted to add: they definetly do put microcontrollers in those, the nodes (the thing with the three prongs) linked together and form a mesh network to send data on usage and breakages, it's actually a really neat idea, and was really useful to facilitate negotiations for power bills of big cities. But sometimes you can't outsmart simple: the city of Montreal (who was our big customer at the time) had all its light fixtures on a timer circuit, by the time the microcontroller was all up and running and the network reformed it was daylight and everything was shutting down again. In the end the data was still gathered and the system was useful, but looking back the timer was probably doing most of the actual work haha

[@andrew2473]

Yet again, you’ve used your technological powers to shine light on an interesting subject. Thank you for your illuminating video. You’ve brightened my day.

[@WarrenGarabrandt]

Pack it in, everyone. Nobody's gonna top that.

[@hoo2042]

These puns are too hot. I'm gonna have to wait for nightfall for things to cool down.

[@raafmaat]

arghhh so much pun, i cant handle it

[@WilburJaywright]

You are under arrest for pun crimes!

[@surkh]

Yeah, I can never resist these videos. Any reluctance I have towards watching 20 minute videos just switches off.

[@D.E._Sarcarean]

Another common method you will see in devices such as those battery powered yard LED lights with solar cells, is the same cell that is used to power the battery during the day, is then used as a switch to enable the LED during night.

[@TheJosh1337]

This is becoming very common in Australia (at least the parts I live) with basically every new street light now being LED. I assume they have electronics to control the on/off state. Yo usee both hardwired versions but also battery "off grid" versions. Then again once you leave the cities the *whole country* is off grid.

[@Incandescentiron]

I worked for lighting design firm and designed layouts for streets, highways, and parking areas. But until now, I had no idea how the photo controllers actually worked. Well done, thanks for posting! And yes, striking an HID lamp requires a large amount of current and is hard on the lamp. A system that works slowly is critical to maintain the life of the lamp. Again, great job explaining the why in addition to the how.

[@nevernever2002]

I have a pretty solid understanding of electronics and controllers(do a lot of hvac work) and I find the breakdowns on some of these oddball topics MASSIVELY useful. I am not a lineman or a dishwasher repairman, so being able to see inside of some of this stuff has helped me work on my own stuff because they end up using the same types of controls and components across a boatload of industries. There's so many appliances I look at now and have an idea of what I'm getting myself into before tinkering around trying to fix them, because of this channel. I don't think I've gotten bad input from a single one of these videos(even when corrections happened for some) because there's such a no-nonsense approach to how and why something does what it does.

[@colinhulme6389]

As someone who knows nothing about electronics, I’m curious: if the light sensor activates during the day, what stops us from just using a NOT gate to flip the output?

[@nevernever2002]

@@colinhulme6389 Pretty sure he covered that. I assume the NOT gate is provided via a plc or something capable of flipping bits on and off in your question- It's because a plc or controller that's similar have many more failure points inherent to their build/design. Each additional wire, chip, board, connector, etc is another way the control circuit can fail on something like this. In the lamp and controls being discussed, this is already a mechanically applied NOT gate - you can view the temperature as the i/o. Above X degrees = 0, below X degrees = 1. If you're a programmer looking to learn a bit more I'd suggest looking up ladder logic and plc programming guides. Lots of free resources and tools that show you how to approach electricity. Flip switches for your lights are just mechanical i/o. If 'yes', light=on. For something like your dishwasher it'll check temps, open valves, close valves check water levels, release soap dispensers, etc with pretty much all mechanical inputs that work based on ladder logic, ladder logic just being another form of truth tables

[@colinhulme6389]

Thanks @@nevernever2002 !

[@nevernever2002]

@@colinhulme6389 No problem, good luck :D

[@stevepettersen3283]

In 1981, I returned home from my three year Army enlistment. While I was adjusting back to my home time zone, I was a bit of a night person. I went on walks throughout the neighborhood and noticed many street lights out. Started recording them and phoning them in to the local electric utility. They were usually fixed within two days, what a difference for safety and security! I ended up expanding the reporting to include pot holes, traffic signs and signals, worn street painting, overgrown trees obscuring signs, etc. Did this for decades and yes, I have no life, but considered it part of public service.

[@0neDoomedSpaceMarine]

Nothing wrong with looking out for your community.

[@Dirsmuutio]

You're a low-key hero

[@railworksamerica]

You’re a good person

[@ForTheBirbs]

In Sydney, our electrical distributor also has a site for reporting outages. Each pole has an ID plate, and the site has them mapped. The only complication now is that new light pole installs in some areas are being funded by local councils. They, of course, have no easy way to report outages. Sigh

[@krovelMx]

12:58 "in many cases, banks of street lights are wired to a central location, and a single one of these is used to control a contactor at the distribution point" Gee, I wonder what those contactor thingies are! Also I love crossovers :)

[@joeslinky]

It’s basically a beefier version of a relay

[@LittleFox94]

@@joeslinky I'm pretty sure they are referencing the existing video about contactors ^^

[@krovelMx]

@@joeslinky I was referencing other TC video about contactors, you should check it out, it's great! (As every TC video is)

[@MCPicoli]

This type of switch was very common around here (I live in Brazil), but no more. All of them are now electronic and have standard relays inside. Also, the LDR is replaced by a photodiode or phototransistor, is tiny and sometimes there isn't even any kind of window to let light in, relying on the light transmitted through the plastic case. Maybe because while 2 or 3 watts times a few million units around the country result in a non negligible use of power, compared with a few milliwatts of the electronic version.

[@JTA1961]

I'm sure that by now they've saved...like...a Brazilian dollars or more...

[@2ndfloorsongs]

​@@JTA1961 Only Technology Connections has the power to encourage reclusive nerds to come out of their shells and make nutty comments such as this.

[@st0rmforce]

I'm sure it's the same here in the uk, now that most street lights are LEDs. It would seem silly to have a control circuit that takes nearly as much power as the light

[@2ndfloorsongs]

Modern LED street lights, or at least the ones I'm familiar with, do indeed incorporate a different type of circuit. LEDs require a regulated (constant) DC voltage and the typical supply is a much higher AC voltage. So a circuit is required to convert one into the other. The circuit is usually a switching power supply. I'll ignore the details, but its design requires a switch between the AC and the DC. Since the switch is already present and required, and is controlled by a small voltage already; it's relatively cheap to have a photocell (more likely a photo-transistor) control the switch as well. In addition, since LEDs require lightning protection, the whole electronic assembly is protected against it by inexpensive components called MOV's. The whole system, including the LEDs, is so much more reliable (labor cost and increased safety) and energy efficient (energy cost) than the old system that the typical payback time for the more expensive new system is less than a year. And because of mass production the cost of the new system is rapidly approaching the cost of the old system and will equal it in a just a few years. (The LEDs are already much cheaper than the bulb.) The main failure mode, by the way, of the old system was those bare electrical contacts which were corroded by the spark that jumped across them as they opened and closed. The component that was analyzed was already obsolete as the newer ones of that design employed a mercury switch that wasn't corroded by the spark and was simply tilted by the bi-metallic strip so that the mercury would run between the contacts.

[@MCPicoli]

@@2ndfloorsongs Sure, the migration to LED street lights is happening... fast! It makes this kind of device almost obsolete, allowing every light to have its own sensor.

[@analogbug16]

When you mentioned Thyristors it brought to mind the classic “Automatic” camera flashes controlled by them. I know you’ve covered film photography before, perhaps you could do a dive into flash photography and the various ways it’s been achieved and controlled. I think that would be quite interesting especially with your presentation style.

[@indyola1]

The magic of the "thyristor" flash units was that they didn't waster power. Before that design, a flash unit would take a long time to charge and use all of the power to flash, even when only a short (dim) flash was necessary. With the thyristors, the flash only put out the necessary amount of light, so often only a very short recharge time was required before the next flash could be produced.

[@yhubtfufvcfyfc]

I am one of the hysteresis people! I feel so seen and I think you do a great job dealing with us pedants. Actually you even got praise from my favorite youtuber this month acollierastro about how well you explain stuff so everyone is satisfied a couple months ago in her video on Gell-Mann Amnesia. Highly recommended!

[@thewolfin]

This might be the most in-depth electronics-focused video I've seen from him, and it's very well-produced. Several times I thought "I'mma leave a comment if-" and then he immediately quashed my urge. Strong evidence of good research and planning. Never change, Alec!

[@expeloco]

Here in Brazil these sensors are completely diferrent! they use a Whetstone Bridge to click a relay, they even have a trimpot sometimes to regulate the amount of light it will turn on or off. I think its a better design because it don't get efected by the temperature of the place, they are a little bit smaller too.

[@stephensnell5707]

You mean affected

[@Hyratel]

one side effect of the thermostatic design is they'll come on earlier in cold weather, while also self-clearing of snow and ice during the day. Cold weather also frequently means bad dawn and dusk lighting conditions

[@paoloposo]

Lots of cities in Germany use a mechanism called ripple control to turn street lights on and off. Control messages are sent by the grid operator by modulating the line voltage (from what I have read), so there is no need for extra communication lines or radio. It's essentially a very low bandwidth form of the power-line communication that's available in consumer products.

[@zeux5583]

Im apprenticeing to become an electrican here in germany and we had to work with street lamps a few times. They do indeed modulate the frequency of the network in the khz range with amplitudes of at most 4% of base net frequency of 50hz and put recievers on lamps which listen on those frequencies. Really fascinating tech. Also the precursor to stuff like powerline communication

[@ronaldwojtylko4375]

One of the advantages of the thermal switch is that it delays the switching action. This is a good thing as in lower light conditions, every cloud that passes doesn't turn on the light. These are used extensively in cell tower/radio tower obstruction lighting equipment. in the case of medium intensity white obstruction lighting, they switch between day/night mode, In the case of day white/red at night they switch between lighting sets. And of course, red at night/painted tower they turn it on and off.

[@EwanMarshall]

Though there are other ways we can do that now, I'm fairly certain we aren't using thermal switch on newer models in some countries just for efficiency reasons.

[@ronaldwojtylko4375]

The problem is that here in the USA, we have to comply with the FCC and the FAA and yes, there are other ways to do this, but lets be honest, these devices are extremely reliable and when it comes to aircraft safety, there is not a lot of pressure to change.

[@Prophes0r]

@@EwanMarshallEfficiency really isn't an issue with a modern implementation. If you are using 1-2 of these to control the lights for an entire parking-lot/roadway, let's say 50 lights, they would consume less power than the wires delivering power to those same lights. 2W is a rounding error. If you were doing it for EVERY light it would probably be worth looking at a different solution, so we did.

[@bentuttle]

So on a very hot day it will just work without the photo sensitive elements at all.

[@Prophes0r]

@@bentuttle It would be a hot day indeed. It looked like that switch was triggering at ~80C (176F), which is pretty high, even for a box sitting in direct sunlight.

[@briantaylor3031]

I seear ive learned more about lights and switching than i ever imagined possible thanks to this channel.

[@Kanbei11]

You could say this channel is illuminating

[@laurenwrubleski7204]

12:19 Thank you! also as an electrical engineer by training I figured on the solution for hysteresis being some kind of op-amp integrator, this solution is so much cleaner (not least because you don't need rectification or voltage conversion), and as soon as you said thermostat at the beginning I went "Oh that's so smart!"

[@airplanenut6242]

My favorite photoresistor nightlights are a couple of LED units which happen to dim the led smoothly as the light increases. This means you can control the brightness by how far away your hand is from the sensor. It’s not better than a simple on/off, but it is more fun. 😀

[@anilykabarry4380]

I loved when you pulled out a big sodium bulb -- to grow tomatoes in the early stages in our greenhouse, we would run these expensive bad boys on 240V to keep the young plants under a constant stream of light and heat; boy do those lights produce a lot of heat! I somehow never made the connection that these would be the same ones used for street lights! It makes sense though; they're bright and have a very long life. Thanks for the video, as ever!

[@JokeswithMitochondria]

Rip your power bill

[@tomhappening]

@@JokeswithMitochondriafunny username. Your whole channeI is a vibe lmao

[@sterlingarcher8041]

@@JokeswithMitochondriaclicked on the profile. Wasn’t disappointed

[@DrLoverLover]

"Tomatoes"

[@johncoops6897]

They put out 1000W of heat, same as any other lamp that consumes 1000W. Or even a heater rated for 1000W. You see, a Watt is a Watt...

[@Drmcclung]

Absolutely love the bimetallic modules for a couple of a reasons; 1) for a simple automated switch they can handle HUGE continuous loads relative to their size (rated 1800w but in reality can handle up to 2300 safely for years and years) 2) high reliability and 3) they fail in the 'on' position which is super important for apartment & security lighting. They really were and still are an elegant solution

[@alisharifian535]

The brief turning on of streetlights after a power outage was a real thing. I used to see streetlights go on for a few minutes after a power off as a kid and wondering what is wrong with the lighting system. There wasn't anything wrong. It was just an artifact. 😐

[@AaronOfMpls]

Though I suppose it could be useful, too, to verify that, yes, all the lights are working. 💡

[@marcusdamberger]

I wonder if street light techs would use this phenomenon of turning off power to check the lights when they turned on the power again to see which ones lit. Often wondered how they check them from ground during the day before going up in a bucket truck. @@AaronOfMpls

[@AstroBax]

One problem with this artifact is that after a massive blackout, when one need to restart the network, any extra consumer that turns back on makes the process more difficult. So in case of several cities having to be reconnected, all those lights will actually be part of the problem

[@vigilantcosmicpenguin8721]

@@AaronOfMpls It's not a bug, it's a feature.

[@renakunisaki]

@@AaronOfMpls just like when you start a car and all the dashboard lights come on for a second, so you know they are in fact working.

[@77Dok77]

That's quite an amazing way of doing it tbh. I assumed they would've used a standard circuit using a comparator etc but it's quite ingenious done with a thermal switch and resistors acting as a heater. I literally lol'd when you said hysteresis because I was thinking exactly that. I enjoy nerding out on your channel :)

[@ChayDenne]

Alec, I started watching your channel about 2 years ago, and ive been hooked ever since. Great videos!

[@filipenicoli_]

I'm finishing my undergrad EE course some time soon and I always liked the relaxed and fun way you conduct your videos. I can't recall you presenting electronic schematics in your older videos and it caught my attention! I truly believe you're helping to encourage some young folks into this wonderful world of electronic engineering (as well as other engineering areas) through tinkering with some basic problem-solving-devices. Nice!

[@SwingingChoke]

Before you finished there are two critical things to do. Have an internship and take the FE exam. This will help so much in getting your first job. It is much harder than expected. I’ve been there.

[@xdevs23]

Very informative! Just one little thing I'd like to mention: 16:50 You can also use one microcontroller to control 100 or even 1000 of streetlights if you just have a central one and wire the streetlights up from there. The microcontroller can stay in a place where the sun does not shine on it.

[@goosenotmaverick1156]

To add, the secondary type of photo switch he showed, is often built into some outdoor lighting, wall packs on the sides of buildings, and some pole lights. It makes for easy install, just a hole in the fixture and wire it up inside. Factory installed on tons of stuff. They are also easy to replace if access to inside the fixture. Both are highly cost effective and used roughly equally, in my experience, on stuff used by the general public.

[@davidbwa]

I enjoy your videos. Interesting information that often takes something I knew about - but afterwards I know more about. Just enough cheesy humor to be fun but not annoying. No annoying looping music track playing over top of your speech. Calm, good video editing without adding a bunch of annoying 'busy' effects the way some youtubers do to make their videos more 'interesting'. Keep up the good work. :)

[@renakunisaki]

This guy has figured out the secret to having a successful channel without putting up an obnoxious Subscribe/bell button animation every three minutes. Turns out the trick is quality. Who knew?

[@61rampy65]

Your videos are getting better and better! And they were pretty good to begin with. Personally, I find the low-key humor highly entertaining, and having the captions on makes it all even better!

[@jayducharme]

I used to have a volume control pedal for my keyboard that used a photoresistor. Unlike conventional volume pedals with pots, this one was really reliable, had completely silent operation and was much more precise. It's amazing how useful light-controlled circuitry is.

[@SHRUGGiExyz]

Now this DEFINITELY needs to be a TC video, that sounds either incredibly complicated or imcredibly clever!

[@jddes]

You answer intriguing questions about everyday items I never knew I had. An upload from you always means a good time. Thanks so much for being you :)

[@JoshuaFlinn-r5s]

I’ve installed thousands of photocells and light fixtures with them and always wondered how the little “snakey” orange thing worked. Thank you!!!!

[@chrisdib9269]

Alec, I've been watching your videos for years now and they've only gotten better. I'm wondering though, why no video on the central vacuum? I feel like it'd fit your channel perfectly and it's definitely an interesting topic, considering how nearly every home at one point was retrofitted for one and yet it died out so fast.

[@jaredwilliams8621]

My dad installed streetlights as a side job for years and would bring me to help. I remember installing quite a few of those light sensors (the cities did 1 per light pole) and even needing to take down a few poles because I forgot to put it in. It's cool to see how those little boxes actually work.

[@robsquared2]

"That's not a light." *pulls out kilowatt light* "That's a light."

[@JayAbel]

Not sure it's used this way, but PTC's can be used for thermal regulation. The photocell will pass current in response to light, and the PTC will reduce the current as temperature goes up. This would be quite helpful in controlling the amount of heat to just what is needed to reach a particular temperature, particularly in cold climates where more heat would be needed in winter than in summer to achieve the cutoff temperature (and keep the resistors from burning up).

[@stevehaflich4531]

It bothered me that this was not addressed i the original video. Obviously these controllers do wirk as intended, but it is surprising )of generated temperature is so important to their operation) that they can work reliable without adjustment both on the hottest full-sun summer days and the coldest, windy, sub-freezing winters. Certainly this must have been considered in the design and evolution of these devices, but it requires consideration and explanation.

[@pratyushjayachandran]

It was not clear in the video how the PTC was wired up but your explanation makes sense. Maybe it was just being used for inrush current protection.

[@scottbez1]

Hysteresis! (12:14 🤣) Very cool to see how the thermal mass of the system adds a delay without any complex circuitry, and prevents fast/erratic switching.

[@bierymolina4379]

that one liner XD

[@kindlin]

I know what hysteresis is, but I totally don't get this reference lol

[@andersjjensen]

@@kindlin Every time he goes "And this little doodad makes sure it waits the appropriate amount of time" someone in the comments will immediately "correct" him and explain that it's called hysteresis.

[@platykurtic5510]

Ok, but it's just rate-dependent hysteresis. It's just a smoothing filter. Does that really count? It's far better than nothing, but there would be a light level where a tiny amount of variation would make it flick on and off intermittently. Ideally there would be a rate-independent hysteresis with a proper bit of memory.

[@kindlin]

@@andersjjensen Oh, alright, I just didn't know the word hysteresis had anything to do with controlling electrical circuits. I know the word as it relates to energy loss over time or work done; specifically, seismic energy dissipation.

[@donaldvincent]

When I was a kid in the 1970's and 80's I received a "Radio Shack Electronics Science Kit". It had many components mounted with springs to attach jumper wires to build projects. One of the projects was this exact device to control a night light. I don't know if they still make any educational toys like that any more. I certainly learned a lot from it.

[@renakunisaki]

I had one of those. Still have it, actually. Fantastic educational toy.

[@KulaGGin]

17:45 _"It's one thing to learn what a photoresistor does and quite another to make something happen with it"_ I made an input lag(motion to photon latency) tester for PC using a bunch of photoresistors that look exactly like the ones in your video but smaller. I wired like 7 of them to an Arduino, then put them next to a PC monitor(spanning across the vertical axis of the monitor), connect Arduino to PC with USB. I also wrote a DirectX program that would by default show black across the whole monitor, and when the left mouse button is held down, it would show white across the whole monitor. Then I made Arduino send Left Mouse click to the PC and wait for the illuminance of the monitor to change from black to white using the array of photoresistors. Arduino measures how much time passed between the moment it sent the signal to PC and the moment illuminance changed, then prints it to the PC console in microseconds. Worked like a charm.

[@Toxis374]

12:39 Another reason why you don't want to use individual switches for each lamp is that they are not exactly identical and you don't want each lamp to switch on at a slighty different time in the same street. On the other hand, it might be intentional to do so on different streets to avoid too high voltage spikes.

[@Neutron66]

We used the power off / on feature to test street lights during the day. Thus avoiding driving around at night to check street light outagages :)

[@johndii2194]

Around here we see the street is on all day or off all night and call the power company and report it. They are very good at repairing the problem.

[@SeanBZA]

Does not catch those lamps that are EOL and cycling though, they normally take 30 minutes to heat up enough to start to cycle, and then will take 30 minutes on, 15 minutes off as the cycle for the rest of the night. Though you do get Osram lamps that are dual capsule, which will immediately start (30 second light off) if it is old and cycling. Also there was some success with making them low sodium and mercury, so they would never heat up enough when EOL, and thus stay with the dim blue Argon Xenon starter discharge in them.

[@Blue_Camera_Cat]

You do such a fantastic job at breaking down and explaining topics. This is such a great video!

[@Owen_loves_Butters]

I swear, Alec could make a two hour long video about paint drying and I'd be engaged the whole time.

I have been teaching science for half a Century and You give me Hope in youth like You. Cheers Patagonia Argentina

[@NoName-ik2du]

I wired the black box style into my porch lights on my house. Cool to see how they achieved the delay to prevent rapid on/off conditions. I've never noticed the lights coming on immediately after a power outage (because that's never a point where I'm paying much attention to my porch lights), but I'll definitely be looking for that next time it happens.

[@whoever6458]

What I've always enjoyed about those sensors on top of street lights is how you can shine a laser at them and turn the street light out for a minute or so. It's very useful for stargazing, especially if you set a laser to hit the sensor the whole time so the light goes out and you can see the stars better. My brother and I used to also troll dog walkers by turning the light out when they walked under it and laughing at them from inside the house.

[@SwingingChoke]

Used to do this too but with an old million candle power spot light. Being 10 years old we felt like some cool kids.

[@Berkeloid0]

Perhaps you're partly responsible for what Wikipedia calls "Street light interference phenomenon", where people believe that they cause street lights to turn off when they walk near them

[@erinfinn2273]

@@Berkeloid0 Had a girlfriend who claimed to turn off street lights occasionally. Never was consistent enough to matter or be provable, but she also had some funky electrical properties due to a lightning strike, so she caused many other things to behave erratically, like touch controls or CRT Phosphors. (Oh, and static shocks off of her in winter would hurt like a mofo, and leave little scars like taser prong burns. She ablated the tip of me NOSE once.)

[@blakksheep736]

@@erinfinn2273 this is, a _little_ hard to believe.

[@Berkeloid0]

@@erinfinn2273 Have a read of the Wikipedia article. It's all basically confirmation bias, drier than usual skin, etc. Nothing particularly mysterious about it.

[@Adamdunnart]

Love your videos just had to comment that when you said "I mean, it's pretty inconsequential, really, but it's still fun." it felt like it summed up my viewing experience well. not all your videos will teach me something I can use in my day to day. or even ever bring up again after having enjoyed the video. but it's all very fun!

[@Incommensurabilities]

5:58 I love how the subtle grin grows across Alec's face as he reveals the daddy bulb 😅

[@afaulconbridge]

As a testament to your power to compel me to pay attention to mundane objects, 4:40 clearly shows the lamp being on yet you said that the lamp was off. You’ve made me care enough to write a comment asking for clarification!

[@Lampe2020]

You could also use a little solar panel connected to a relay to have a colder version of that thing, like in the little garden night lights that run off a rechargeable battery. (the solar panel charges the battery in the day and when it gets dark enough it triggers the lamp and stops charging)

[@Prophes0r]

This is done. But it is also wasteful in it's own way. Those batteries are consumable. The solar panels are consumable. The maintenance/replacement costs are orders of magnitude higher. It is still useful to have that solution in your pocket for when it really IS the better solution, but 99.999% of the time it isn't.

[@MrKyltpzyxm]

​@@Prophes0rone of the things this channel has highlighted for me is the difference between durable goods, and consumable goods. Things like solar panels and rechargeable batteries get close to that dividing line. How many use cycles can you get out of a system before it goes from consumable to durable? I guess a good reference would be the rest of the object. Whichever piece wears out first is the consumable. 😂

[@Prophes0r]

@@MrKyltpzyxm Solar panels need a lot of cleaning to keep working properly. Most commercial setups get cleaned weakly. You could oversize them so the 40-50% operating efficiency let you go longer between cleanings, but now the panels are getting wastefully big. (They are plenty good for temporary installations though) As for batteries? They fall well below the threshold of consumable. This is especially true for ones that have to live outside. Also, remember that there is a difference between servicing and replacement. Changing out a bulb 1-2 times a year is not at all like changing out 20-30kW/h of batteries.

[@Lampe2020]

@@Prophes0r In street lights the battery would obviously not be needed and instead the solar panel would just trigger a relay or transistor.

[@Prophes0r]

@@Lampe2020That loses the hysteresis. Clouds, shadows, dirt, etc could cause enough voltage drop that the light is triggered on, which is unhealthy for the bulbs. Additionally, a relay is MUCH more consumable than a bimetallic strip. The contact points wear away, especially in high wattage situations. It certainly would work, but it would do a worse job that this solution does.

[@psirvent8]

Here in Europe we have relay-based photoelectric switches for the streetlights (Often controlling a bank of lights instead of having a sensor per light), that have a small solar panel inside them and there is an adjustable time delay as well. They surely use electronics, and the time delay is there to keep the dusk/dawn erratic behaviors mentioned in the video from happening.

[@haroenv]

I’ve definitely seen timer-based systems here too, as usually lights are off during the middle of the night

[@jaisbr]

I was about to say, I thought they were photoelectric because in Australia we call them PE cells.

[@andrewmurray1550]

What's the purpose of the solar panel - to power the time switches or charge batteries for the time clocks? Obviously not for powering streetlights at night.

[@psirvent8]

@@andrewmurray1550 The solar panel is only used as a light sensor in lieu of a photoresistor, the time switch itself being powered by mains voltage.

[@psirvent8]

@@jaisbr What I'm talking about is something that generates voltage from light, like the small ones on calculators and the large ones on some roofs. Here it's used as a light sensor, not to generate power.

[@pileofstuff]

I've seen 2 other implementations of the street light sensor, both with more electronic solutions. One used a dual comparator chip and the other used a 555 timer to control the a relay (Big Clive did a tear-down of that one)

[@leonardfibigerlewis]

Howcome I have not found this channel earlier? Mr, you explain electronics in a very relateable way. Thank you for this channel, may you be blessed beyond your wildest dreams.

[@clcsqueejy04]

12:19 as an electrical engineer who was begging for mention of the word hysteresis during this conversation, this made me laugh exceptionally hard lmfao. Nice work Alec.

[@vk3xe]

Yet again as a software developer I’m impressed that electrical engineers come up with some odd ball solutions to make things work

[@LMacNeill]

So instead of saying "be home when the streetlights come on" when I was a kid, my mother *should've* said "be home when the bi-metallic strips cool down enough to close the circuit." 😂

[@TheEDFLegacy]

🤓😅

[@BEM684]

When I was in high school there was a highway overpass near my friend's house with lights underneath it, controlled by some sort of light sensor. His street ended right across from the sensor, with the overpass being just a few yards to the left. We used to flash our highbeams at it to make the lights turn off at night. Sadly this doesn't work anymore - I took my kids on a tour of my hometown and tried it as we drove by.

[@Rob.DB.]

I belive you buddy. things were just better way back in th day. hope your kids didnt think you were crazy.

[@BEM684]

@@Rob.DB. Oh they definitely think I’m crazy but not because of this!

[@stevebunes9151]

Credit where credit is due. I would have to say that over the years your clarity has increased tenfold. Really excellent presentation of whatever technology you are explaining. I like the fact that you use the word contactor instead of relay as well. Nice attention to detail. You might have explained that contactor is really just a form of a high current relay with good longevity, but now I am nitpicking. Keep up the good work!

[@derPatte26]

Did I just noticed, that you ended the video with rolling credits?? I know one other channel, doing that and I find this sooo cool every time how to lead over to this last ending of the sentence of the video with rolling credits. Chapeau! And the topic? It’s every time amazing, how little we care about the greatest and often simplest technologies and hacks making our lives so comfortable and how well you explain them. I love it!

[@MattGodbolt]

Omg totally called out as I thought "isn't that hysteresis?" And then.... 😂

[@coriscotupi]

Great content, always informative and fun to watch. And: _"All it takes ... is for someone to make the connection"._ Not only a pun but a full, double pun. Well done, sir.

[@AlexandreMacabies]

Hm, three if you also consider this channel's name?

[@coriscotupi]

@@AlexandreMacabies Yep! 🙂

[@RobertCoxEsq]

You are able to keep producing such wonderful and informing content!

[@tedbell4416]

Thank you Steven

[@Sonny_McMacsson]

A myriad plethora cornucopia of things exists. His job is to entertain us about it.

[@Pip2andahalf]

Another home run, Alec!!! Great vid. Love the thermal imaging. And as always I love your set. Lava lamps 7x was fun haha

[@rodolfoandrade7453]

Long time fan here, just to say that I had no idea how much more enjoyable this videos were when going to sleep after a night out. I was like "aight, now the party starts"

[@RHauto]

When I was young I learned how to cut power to entire car parks shining my phone torch into an Light dependant resistor. I thought it was the coolest thing ever! Lol. Especially when there was hundreds of people gathered there at night for a car meet, all of a sudden the place descended into darkness and everyone went wild 😂

[@paulkocyla1343]

LOL. Same here. When I was a kid, I discovered a photoresistor inside a drill hole of an electric box on the street. When I covered it up, all street lights went on - with a bang from the contactor. I played with it every time. Power of the gods 😀

[@RadDadisRad]

Burning lasers do that too

[@JaenEngineering]

​@@RadDadisRadjust a normal laser pointer will do. Don't need to be a vandal and destroy it just for a little high jinks

[@RadDadisRad]

@@JaenEngineering depends on the sensor. A red laser wont activate the sensor but a green laser will.

[@RadDadisRad]

@@JaenEngineering you also don’t have to have a full power black laser either. It’s the operating frequency of the light that is important, you can throw more resistance in the circuit to decrease light output from the diode. The laser works in nanometer to visible spectrum which these resistor chips in photocells work best at because they use visible light radiation to activate/deactivate.

[@itskdog]

Interesting video! Until about 6-7 years ago when the lampposts near me (west London) were replaced with white LEDs (not just drop-in replacements, but taking down the old posts and replacing from scratch and you can see each individual LED as they have a centimetre or so gap between them) it used to be that every lamppost would have their own sensor and they'd turn on and off at different times as a result. (Probably better on the grid by not causing a power surge, to be fair) The new lampposts have what looks like an antenna (or some other thin, vertical, stick) on the top of each one that is presumably triggered by a timer or photoresistor somewhere else, especially as they were kept on 24/7 for a few weeks while they were being installed across the borough. Occasionally you get one that doesn't turn off in the morning, but that's very rare from my experience, and being LEDs it's not like they draw much power anyway, and they're often in a position where they have a chance to get blocked by a tree growing around them. I remember a kids' TV show showing a light not working including an engineer using a cloth in his hand to cover the sensor to test if the replacement bulb was working when he'd fixed it. Edit: also yay we have the jazz back!

[@Lizlodude]

I too was disappointed in the lack of jazz in the last video

[@Conchobhar]

Dude I love it when you connect technologies like that.

[@mhfs61]

Thank for this lecture. Never knew I wanted to learn about these topics. I stumbled on your channel by KZbin recommendation. The first video I’ve watched is the rice cooker one. I like your clear explanation, without dumbing down and comedic remarks sprinkled here and there.

[@RavenLuni]

Software engineer here. Microcontrollers are so overused for situations where they aren't necessary. So many ways to do things but the simplest ones will always be the best. (No cats were skinned in the making of this video)

[@ryukisai99]

Thanks for your videos! I happily watch all of them mostly as soon as they release for three obvious(ly subjective) reasons: 1 there's always something interesting (at least for geeks i suppose) to learn, 2 the quality of your writing, speech and presentation are really high imo, 3 the end credits’ music track, of course!

[@randysterbentz5599]

18:06 "All that it takes to turn that into a useful ***Technology***, is for someone to make the Connection." HOW DID YOU NOT???????

[@mangamaster03]

6:30 I am so glad this was marked as "simulation." Otherwise I might have wanted to try it.

[@FalconFetus8]

This has to be my favorite episode! So simple, yet so informative!

[@maxresdefault_]

This felt like a real old school video, just interesting information delivered in an enjoyable way

[@phinok.m.628]

Thanks, hysteresis to you too. But only for the temperature at which the thermo switch switches, not for the delay caused by the heating/cooling down. :P About the light control itself. There would be many many fairly simple ways to do this without a microcontroller and without wasting much power, just needing like 3 more components. I think it mainly boils down to reliability. Any part you add, is a part that can fail. And as you mentioned, in this case you get hysteresis and a little moving average filter for free, using very little components, all of witch aren't particularly prone to failing. I believe the reason it heats up to turn the light off, is mainly so the most likely failure mode is for it to turn the lights on constantly, instead of off. This way the lights are still on at night, so they can replace the sensor within the next week or two, without any safety concerns due to the lights being off (which are obviously there for a reason).

[@Pentium100MHz]

The comparator will need a power supply, which will add to the cost. The cheapest would be a CR dropper and a zener diode for voltage regulation). It would save a little bit of power at the expense of making it more expensive and maybe less reliable (capacitors). Also, the little amount of heat that is produces by this switch probably helps to melt the snow in the winter, so you do not need another component for that.

[@phinok.m.628]

@@Pentium100MHz Then don't use a comparator... Like I said, there are countless ways to do this. You could even just use circuit inside the night light, to close a relay. You may wanna use a triac instead of a thyristor, in order to get both half waves of the AC voltage. And possibly add a resistor or two in series with the triac, to shift the switching point when the triac is on (in order to add hysteresis). Delaying the switching action is a little difficult without using a capacitor. But there are very reliable and cheap capacitors, you don't need to use unreliable electrolytic caps. I'm sure it may increase the cost by a few cents. But then again, it also saves power. The heat melting the snow is a good point. But of course, you could also place a roof over the sensor and have it look out to the side or whatever, I'm sure there are plenty of ways to overcome the snow problem as well. Like I said, I presume they do it this way to reduce the part count and therefore the failure points as much as possible while also keeping the price down. And really, two watts more or less, doesn't make a huge difference compared to the many hundred watts of a whole block of street lights, so why make it more complicated than it needs to be, right?

[@Pentium100MHz]

@@phinok.m.628 "why make it more complicated than it needs to be, right?" That's my point as well. Power usage is not the most important thing. Everything is relative, the 2.5W is pretty much nothing. Maybe even making the device more expensive to save power could be possible, but if that made it less reliable, then, well, I am sure it costs way more money to replace it than the device itself or the power it uses. Similar to how people in the past tried to make steam locomotives more efficient in different ways (compound engines etc), but that made the maintenance costs go up and while you saved some money on coal, you spent more on maintenance.

[@carlphilipphohl3852]

It is sadly not inconsequential if all street lights turn on after a power outage. Makes black and brown starts of a grid even more of a nightmare than it is anyways.

[@kenbrown2808]

nowhere near as not inconsequential as everybody's electric climate control system trying to start up is though.

[@TechnologyConnections]

Eh, compared to all the other loads that are immediately trying to come on, I doubt it's significant. Besides, the power grid has to handle _all_ street lights coming on within the same 10-20 minute window every evening.

[@SeanBZA]

@@TechnologyConnections Not really, group control will take roughly an hour to switch the entire metro on or off, as each group photocell has varying amounts of shade on it, and the light levels are not too tightly controlled as to exact switch point, that has a pretty large variation between each photocontrol. Biggest thing is all those cold water heaters all sitting there already on, waiting for power, that is a massive surge.

[@odius94]

@@SeanBZA Those are all resistive loads so not that big of a deal on grid restart. The inductive loads of motors though, like in HVAC systems, are a big issue with inrush current causing voltage droop.

[@TheEulerID]

@@TechnologyConnections I would agree it's inconsequential, but all the lights coming on over a 10-20 minute interval, but staggered due to variations in the detectors and their local light condition is entirely different to simultaneously switching them all on when power returns.

[@RoboticParanoia]

I live in Brazil and I envy the simplicity of this socket mount sensor. I use some of them at home to control outdoor lights and recently replaced one unit that malfunctioned, and started to turning the lights off erratically. It have a transparent body, so I can see it uses a led as sensor, connected to a very populated circuit board. I changed for an opaque one with a weird milky white lens, I doubt it has less electronics inside since in the blister there's a model list from the manufacturer and one of the models says "wifi".

[@fascistpedant758]

Some domestic controllers can be programmed to turn on at dusk and turn off at a given time so the light doesn't shine all night when you don't need it. They often have motion detectors also.

[@RoboticParanoia]

@@fascistpedant758 yes, I have one with motion detection at my front gate. This one I mentioned is the simple light sensor.

[@Itsdirtnaptime]

So I was watching a completely random video on a channel I never seen before. He dropped in a random segment with a backdrop that looks ironically similar to yours. He may have even used your phrase, "Through the magic of buying two." I think it was a fun homage to you.

[@koston_varjo3536]

"...which you can perhaps tell by the massive lack of stuff inside of it." -TechnologyConnections I love it!

[@randomcow505]

back in my home town there was a very straight street and at sunset the lights would light one after another at the perfect speed where if you started walking at an average pace it would seem like you were the one turning the lights on as you walked under them always thought it was something to do with the earth spinning, so the light hitting the sensors on top of each post was just different enough to cause the effect starting to think now that It's something to do with how the lamps heat up or they have timing circuits inside and some local sparky setting them up had a good time setting them all just slightly different

[@techno1561]

Could also be that the lamps were sequentially activated so they didn't all overload the power supply. A little delay to let the lamps start up, and the current to drop before clicking on the next. If they all clicked on at the same time, they might have browned out the street, or blown the fuse.

[@Rob.DB.]

Moo, moo.

[@AdamsHangar]

You're channel is so fun and relaxing to watch. I've watched a lot of your videos and it is cool to finally see one that is current. The bloopers at the end are always hilarious! Thanks for producing these, they are quite fascinating 😀

[@JTA1961]

Well said

[@malucullus9100]

There are definitely some thyristor-based streetlight controllers on the market, I have taken a few apart. Another interesting tidbit - at one stage in the UK, streetlights were controlled by pulses put onto the mains waveforms. Early switchmode power supply’s were sometimes known to put so much noise back into the mains that they would activate nearby streetlights when used.

[@Lenny-kt2th]

I think the technique you're referring to is "ripple control". To this day it is in use in the Netherlands to switch street lights, but it is being phased out. Tariff switching of meters using ripple control has stopped in 2021. A lot of LED lighting equipment is rather sensitive to this ripple control signal leading to complaints of flickering lights at certain times of the day. Added to that it's an expensive and obsolete technology.

[@RoseRodent]

Pleased to see the captions still getting so much love, i MASSIVELY appreciate the quality of the captioning and the caption jokes, just amazing

[@aboriani]

I just saw the "perpetual motion" video from Steve Mould channel, and after hearing the music, I realized how much I love this channel! I had to come here and say thank you for your work!

[@awetisimgaming7473]

I was looking into buying a switch like this for a bit, but this video showed me I can just use the photo resistor directly. I wanted to implement a daylight sensor in a car, and I'm already using a raspberry pi of sorts to control a bunch of junk, so I'm glad this could help me save a bit of money and complexity

[@CalebFrey]

He said hysteresis! Hysterical!

[@m1geo]

I had one similar with LEDs. Mine used 3W to save 2W of LED. I just ditched it and the LED runs 24/7 now! 😂

[@sullysullivan1282]

It took me until today to notice your 'theme song' was in the youtube audio library. I always thought it was so neat how it got all 'beepy' right as the end card showed up. This song, as far as I'm concerned, is quintessentially Technology Connections. also it is infinetly amusing that looking it up (and not following youtube's link, where the comments are disabled) are literally all about warming their harts through the 'latent heat cycle'

[@prototypedenNIS]

Great video. I work as a rep in the electrical industry. I work with one company that makes these and another company that makes a plug and play GPS timer actuated one (GPS Litelock). The GPS one locates its position and will turn on at sunset and off at sunrise automatically. There have been timers designed for this application but they need to be reset with power loss. Thanks for the video. I'll be sharing it on LinkedIn.