Photoelectric light controls are weirder than they seem 

Usually the magic of buying two

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

@@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...

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. 😊

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

*_BUT SOMETIMES!_*

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

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

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

​@@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.

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

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

​@@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.

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

@@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.

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

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

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

Laser too

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.

anarchy in the UK

@@danb9447 It was scientific experimentation. Honest!

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.

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.

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

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

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

Source?

@@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.

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.

Nothing wrong with looking out for your community.

You're a low-key hero

The software issue was amazing hahahhahahhaa

undoubtedly a dig at adobe premiere 😆

@@blaknoizee A picture is worth a thousand words.

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.

@@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!

Illuminating, you say...

LIKE LIGHT!

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!

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

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

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

@@unemployedgringo you'll find your queen someday king

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

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

arghhh so much pun, i cant handle it

You are under arrest for pun crimes!

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

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.

@@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).

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

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

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

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

@@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.

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

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

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

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.

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?

@@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

Thanks @@nevernever2002 !

@@colinhulme6389 No problem, good luck :D

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.

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

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

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.

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.

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!

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.

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

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.

You might want to watch some of Big Clive's videos. He does a lot of reverse-engineering of consumer electronics and is pretty entertaining to boot.

​@@mattgiesClive is a legend

@@mattgies Is that the one that drinks while he's doing teardowns? There's a guy on RU-vid that drinks and gets stuff wrong a lot - not sure you should be learning from that one 😅

@@3nertia I've never seen a beverage during a teardown. He does use a SodaStream to carbonate random alcoholic beverages, though, in a very different genre of video he also does.

@@mattgies Yes, it was my mistake. I was thinking of pileofstuff! Apologies! I watch a lot of these sorts of channels and they tend to get all jumbled together in my head sometimes 😅

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

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

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

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.

@@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.

that one liner XD

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

@@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.

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.

@@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.

You could say this channel is illuminating

Rip your power bill

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

@@JokeswithMitochondriaclicked on the profile. Wasn’t disappointed

"Tomatoes"

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...

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

It’s basically a beefier version of a relay

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

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

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.

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.

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.

@@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.

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

@@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.

🤓😅

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?

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

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

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.

@@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.

@@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.

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.

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.

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.

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

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

@@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.)

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

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

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.

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.

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

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 😀

Burning lasers do that too

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

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

@@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.

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.

​@@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. 😂

@@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.

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

@@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.

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

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

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

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.

@@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.

@@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.

@@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.

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.

@@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?

@@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.