Small UK owned streetlight design company cannot design own LED drivers? - Page 1
Forum section: electronics / general

author: ocset
author_rank: Super Contributor
timestamp: August 05, 2018, 08:41:55 am
content: Hello My friend works for a small Street-lighting company in the North of UK.He says that whilst working there he is condemned to never being able to use his SMPS design skills…is this likely to be true?His company buy offline LED drivers as follows from eg Philips………………http://www.docs.lighting.philips.com/en_gb/oem/download/xitanium-led-drivers-outdoor/Xitanium_150W_0.1-1.05A_Prog_GL-F_sXt_929000709003.pdf…they then fit these offtheshelf LED drivers into the lamp head, and voila….sell the streetlight.Electrolytic capacitorsAll the available offtheshelf , offline, isolated LED drivers for streetlighting , contain electrolytic capacitors. This is because this is the only practical way of preventing serious levels of 100Hz flicker in the light of the LED streetlight. (film capacitors could be used to help prevent high levels of 100Hz flicker, but it would be way too expensive to replace electrolytics with film capacitors) Serious 100Hz flicker is not illegal for streetlighting (neither is it in any way harmful)…however, high levels of 100Hz flicker are illegal in Europe for indoor lighting…and the fact that this is the case, is used as a scaremongering tactic to deter European customers from even accepting high levels of 100Hz flicker in streetlighting.Electrolytic capacitor free streetlight driverAnyway….he was told by his boss that he would be tasked with designing Electrolytic capacitor free offline streetlight drivers using SMPS……(the boss even managed to get a business development grant in order to investigate this)……the thing is, the 100Hz flicker problem virtually certainly means that this project is a hopeless loss maker……..seriously 100Hz flickering streetlights are never going to sell …at least not anywhere in Europe. (there’s no sane reason for this, but its just the way things are and will stay.)Not only that, but a reasonably priced, isolated offline electrolytic-capacitor-free streetlight driver would likely use a single_stage_Flyback SMPS……..Due to being a Flyback, (and the high RMS current in it since it appears straight after the unsmoothed mains bridge output) such a converter would likely be less efficient than an offline led driver comprising a Boost PFC followed by say a 2-transistor-forward converter. (admittedly the latter would have an electrolytic capacitor bank after the Boost PFC stage……but it would likely be more efficient than a single_stage_Flyback of the same power level….so its another nail in the coffin of the electrolytic-capacitor-free, isolated LED streetlight driver…(OK there are ways of doing it more efficiently, but these are too expensive)As such, my friend believes that this electrolytic-capacitor-free streetlight driver task that he has been tasked with is a "no-hoper"…as soon as the Business development fund money has run out….then so will the task just die off.Compete with the major electronics corporationsThe other alternative is to actually design an offline, isolated LED streetlight driver with electrolytic capacitors and try and compete with the major electronics corporations such as Philips, Tridonic, Osram, Samsung etc etc…………….This is surely hopeless…..there’s no way a small company would be able to get the kind of component cost-downs that the big electronics corporations can. Not only that, but the mainland European electronics corporations, have benefit-clique style relations with the European semiconductor fabrication plants, so they can get components far cheaper than a UK company would be able to. (there are no major semiconductor fabrication plants in the UK, neither are there any significant UK owned electronics component makers).So do you believe it is true?….can a small UK company never be able to design its own offline, isolated, SMPS based LED streetlight drivers as part of competing in the streetlight sales arena?The company are deterring him from trying to leave by saying that he will be able to design offline streetlight drivers at the company. In truth, he believes that this is never going to be the case…the streetlight market is one of huge volumes, and the huge European electronics corporations have it totally wrapped up.Chinese importsMy Friend believes that the real reason that they want him to stay…… is to do bits of general software and general analog interface circuitry…something that in truth, they would be better off getting a different engineer for. Also, the company buys in lots of Chinese made SMPS based lighting, and middle-mans it onward, and it is deemed that it kind of helps to support this business if you have an SMPS engineer in-house…(every now and then an imported Chinese SMPS may fail, and it is deemed to help if you have an engineer in house who can make out some kind of technical-sounding report on what may have caused the failure)…..in truth, this job hardly needs anyone with SMPS design skills…since the company don’t even have the schematics of the Chines import products.Another point, is that when UK leaves the EU…the UK government are likely to impose high tariffs on these Chinese imports, and so this may well close down a lot of small UK owned lighting companys……..because the Chinese import business is said to be the major profit making activity of small UK owned lighting companies.In the UK, there are actually a number of “electronics design” companys which are no more than “puppet companys”…pretending to be what they are, when in fact, the “real” company is in China…and the Chinese simply use the” UK company” as a vehicle through which they can import their Chinese products into the UK and the EU without paying the import tariff….the UK “puppet company” is usually a very convincing disguise…they are staffed with British “engineers” and sales staff etc etc…you would just think it was a totally British company….you would never realise that everything was being designed in China, and then transferred across to UK. The Chinese secretly direct all operations in the UK “puppet company”. I think the UK government will hunt down these puppets after Brexit, and impose huge tariffs on them…closing them down.So do you believe it is true?….can a small company never be able to design its own offline, isolated LED streetlight drivers as part of competing in the streetlight sales arena?

author: tggzzz
author_rank: Super Contributor
timestamp: August 05, 2018, 09:01:32 am
content: Are your other threadshttps://www.eevblog.com/forum/chat/why-do-cash-strapped-electronics-manufacturers-in-uk-go-to-expensive-areas/msg1448687/#msg1448687https://www.eevblog.com/forum/chat/how-does-a-small-company-start-making-led-streetlight-drivers/msg1442260/#msg1442260https://www.eevblog.com/forum/projects/common-mode-emc-problem-in-offline-led-driver/msg1435168/#msg1435168https://www.eevblog.com/forum/projects/mains-transient-protection-circuit-looks-very-bad-should-we-bin-it/msg1393480/#msg1393480https://www.eevblog.com/forum/beginners/long-mains-cable-leading-to-product-filters-noise-out-or-brings-more-noise-in/msg1373512/#msg1373512in any way relevant or associated with this topic?Quote from: treez on August 05, 2018, 08:41:55 am"Your friend" in the "North" should ignore his engineering judgement and believe everything that other people tell him, without reservation. Or not.QuoteIf "your friend" is unhappy, they should leave and become a consultant.If "your friend's" calling in life is to design SMPSs, then they should emmigrate to somewhere where SMPSs are designed.Othewise they will have to compromise and change.QuoteOf course they candesignone.

author: Zero999
author_rank: Super Contributor
timestamp: August 05, 2018, 09:09:20 am
content: I do think a lot of flicker would be a problem with street lights. I've noticed it with old sodium lights and found it distracting. An LED light with a large chain of LEDs and a capacitive dropper could be worse, as the duty cycle would be low.Not using electrolytic capacitors, sounds daft to me. They can be very reliable, if used properly. There are some power supplies where I work which have electrolytic capacitors and have been continuously powered for over a decade with no problems.There could be other reasons for needing large capacitors, such as power factor correction, which might be a requirements for modern street light LED drivers.Of course it's possible for a small company to design their own LED driver, but whether it's profitable to do so or not is another matter.

author: ocset
author_rank: Super Contributor
timestamp: August 05, 2018, 09:18:28 am
content: Thanks, I believe there is some SMPS design work in UK….but generally for low volume markets….or startup companies who just need some power in whatever physical space to power whatever prototype they have.Also, I appreciate that you both know that a single stage Flyback PFC LED driver can be done, and not need any electrolytic capacitors (no large capacitor banks)..and be PFC’dQuoteThanks, whether it is or not...the public have been whipped up into such a furore of fear of high levels of 100Hz flicker that there is no chance of selling these kind of lamps into the streetlighting market. In my opinion.....it doesnt matter for streetlighting.Ive never seen a light output waveform for a sodium streetlight, but i understood that their "persistence" meant that they dont flicker at all?

author: tggzzz
author_rank: Super Contributor
timestamp: August 05, 2018, 09:30:10 am
content: Quote from: treez on August 05, 2018, 09:18:28 amSome peoplearemore sensitive to flicker than others. Henceyournot being affected isn't a good indicator.QuoteHave you tried measuring it?

author: jpanhalt
author_rank: Super Contributor
timestamp: August 05, 2018, 09:38:06 am
content: @treezThis question seems to be a recurring theme for the more than 4 years I have read your posts, e.g.,https://www.electro-tech-online.com/threads/uk-universities-have-stopped-teaching-analog-electronics-on-electronics-degree-courses.139537/#post-1162906Remember, you can't do great things, if you are not there. "Being there" means accepting what you can't change and contributing to what you can. Or, start your own business.I suspect you are in the former group. So, at your next job, show you know how to make a decision without worrying it to death on the Internet.With best regards, John

author: bob225
author_rank: Frequent Contributor
timestamp: August 05, 2018, 10:10:51 am
content: At the end of the day its down to cost,Why R&D and spin your own when you can buy in the equivalent electronics from a supplier with years of experience in the field and they have the items on the shelf for when you need them with warranteeor£50-70k a year engineer, tied up for possibly years on 1 project with £100k worth of inventory and a lab full of equipment - then the cost of having the equipment certified and not forgetting you will have stock sitting on the shelf, EOL comes around and its dead stock only fit for the skip

author: NivagSwerdna
author_rank: Super Contributor
timestamp: August 05, 2018, 10:11:51 am
content: Quote from: treez on August 05, 2018, 08:41:55 amAnd they make money? If so, it's a winner.The alternative has huge risks and potentially limited up-side. Maybe your friends design skills aren't up to those in the competing product, maybe the cost of the development cycle would be high, maybe sourcing individual components and assembly would be problematic. In summary maybe it's just not worth the risk/cost of in-house?

author: IanB
author_rank: Super Contributor
timestamp: August 05, 2018, 10:33:08 am
content: The obvious question here is about the difference between design and manufacture. If Phillips sells a power supply module for lighting, do you think, maybe, that Phillips had in-house engineers design it? And that perhaps those engineers were based in Europe?Maybe Phillips has significant expertise in this area built up over the years with a staff of very experienced designers who have done many, many products in their career?Maybe Phillips doesn't just go out to the Shenzhen marketplace and pick an off-the-shelf product to buy and re-sell that ticks certain boxes?

author: Zero999
author_rank: Super Contributor
timestamp: August 05, 2018, 10:42:40 am
content: Quote from: treez on August 05, 2018, 09:18:28 amWhy would there be any persistence in a sodium discharge lamp? There's no phosphor. When the current is zero, the lamp stops emitting light, except maybe a tiny bit from the hot electrodes. I think you're confusing them with fluorescent lamps, which have a phosphor and persistence.Sodium lights do produce some flicker, but not much, because the lamp conducts most of the time.LED lights aren't always better for the environment, than sodium lamps. The broadband emission is more similar to moonlight so can have a negative impact on wild life, such as turtles nesting on beaches, where the offspring can be confused and go towards the city, rather than out to sea. Sodium lamps have a narrowband output in the yellow region, which is more turtle friendly. Of course it's possible to use yellow LEDs, but they aren't as efficient as sodium lamps, which incidentally are actually more efficient than LEDs, at higher light intensities, although they have poorer colour rendering and lower efficiency when it's darker, hence why they're now being used for street lighting.

author: ocset
author_rank: Super Contributor
timestamp: August 05, 2018, 10:52:41 am
content: Thanks...The point of Chinese imports of electronics products into the UK is a point of concern for small UK electronics engineering companies. Many of them are masquerading as electronics engineering companies, (with a token group of British made products ….etc etc). As such, they are more easily able to act as “middle-men” for large quantities of Chinese electronics into the UK and beyond.The EU has recognised that this has actually been going on throughout Europe….and so the EU is literally closing down ports on the European mainland so that there are fewer conduits through which Chinese imports can get into the EU without being detected by EU customs. The remaining few ports are tightly regulated by EU customs so that all Chinese imports are registered, and exposed to the tariff system of the EU. British ports, up until now, have been free of this regulation of UK ports, so Chinese imports can even get in to UK without EU customs knowing. Suffice to say that nobody in UK actually wants UK companies to pay tariffs into the EU central bank anyway. What would be the point of that? None.The EU has even arranged a rail ink direct from China into the EU…It has a few stations which again , the EU has tightly regulated with its customs officials. Trains are convenient because they can’t swerve off the tracks and avoid the customs officials.The point is that UK is totally flat broke….2 trillion in National Debt……and UK has sold off most of the industry needed to pay off the debt…..so after brexit, the UK government will tariff high heck out of Chinese imports into UK, and will enforce this from within UK…this will result in a lot of small UK “electronics companies” going straight out of business........because their lucrative Chinese import middle-man business will be smashed.

author: ocset
author_rank: Super Contributor
timestamp: August 05, 2018, 10:57:46 am
content: QuoteThanks, i just notice that when they are switched off, they seem to still be shining on for a while, before eventually dwindling out

author: bob225
author_rank: Frequent Contributor
timestamp: August 05, 2018, 01:02:18 pm
content: Quote from: treez on August 05, 2018, 10:52:41 amYour 20-30 years late, electronics is a very niche market compare to what it was back in the 90's most of the manufacturing and skills base has gone to Asia, its uneconomic to repair electronics as the cost is usually 40-90% of a newer comparable product (retail type electronics)I can get a prototype PCB manufactured in china for a 10th of the cost of a uk suppler, I can even have it built in china for a 1/5 of the costMargins are so tight in the uk, Especially in pc building you need to turn over 8-10 machines a week to put food on the table

author: ocset
author_rank: Super Contributor
timestamp: August 05, 2018, 01:44:25 pm
content: Bob225 I Agree entirely with what you say...and if you read my posts above, you will see that i agree with what you say.The situation is, that the "middle men" companies of UK will be heavily tariffed by the uk government after brexit..this will smash them.These middle men companies exist entirely for the import of chinese goods into UK..

author: janoc
author_rank: Super Contributor
timestamp: August 05, 2018, 01:46:33 pm
content: Quote from: treez on August 05, 2018, 10:52:41 amSeriouslyjustAnd you think that the good serious UK companies will spring up overnight to replace all those now heavily taxed goods that your economy actually relies on. And will be able to replace them at the same costs as you were used to, right? Not at all jacking up prices when there is no competition (and also because manufacturing costs in UK are 10x higher than the Asian ones).Good luck explaining to the UK consumers why a new iPhone costs 50% more in the UK than across the border in Ireland or France (if you think Apple or others will suddenly move their manufacturing to UK to avoid tariffs you have to be smoking crack). If your government actually does this, great - a perfect example how to commit a political suicide.Seriously ...

author: tggzzz
author_rank: Super Contributor
timestamp: August 05, 2018, 02:51:57 pm
content: I wondered how long it would be before someone picked up on treez' arguably political statement, and mutated the thread in to a political Brexit discussion.I avoided commenting in treez' statement for just that reason.Yes, that is a hint.

author: Zero999
author_rank: Super Contributor
timestamp: August 05, 2018, 03:57:36 pm
content: Quote from: janoc on August 05, 2018, 01:46:33 pmYes, that's why electronics are low cost commodity items today. Just look at the prices of TVs back in the 60s, compared to averages back then!There is an argument for making electronics more expensive, to cut down on waste for the sake of the environment, but it's a totally different one, than that made by those who want to bring back manufacturing jobs.Quote from: treez on August 05, 2018, 10:57:46 amWhat sort of sodium lamps are those? Low pressure or high pressure?It's most likely due to incandescence and the persistence of the image on your retina could also explain it.Unless there's some new hybrid sodium-fluorescent technology I'm not aware of, sodium lamps do not use phosphors.https://en.wikipedia.org/wiki/Sodium-vapor_lamp

author: doobedoobedo
author_rank: Regular Contributor
timestamp: August 05, 2018, 05:20:04 pm
content: Treez likes to pretend he's British, and knows about the UK. I personally think that everything he says is made up. I very much doubt if he's ever been here or even knows anyone here.I'm sure he'll like this post too.

author: IanB
author_rank: Super Contributor
timestamp: August 05, 2018, 05:20:48 pm
content: Quote from: Hero999 on August 05, 2018, 10:42:40 amBecause, hypothetically, it could act like a capacitor, or charge storage device, and the electric field in the tube may take time to discharge?Because, hypothetically, the electrons surrounding the sodium atoms that have been raised to a higher potential by the electric field may take time to decay back to the ground state (there may be a time constant for that decay).I do not know the physics, and the above hypotheses may be wrong, but I do not see a basis for simply ignoring the possibility without evidence to the contrary.

author: IanB
author_rank: Super Contributor
timestamp: August 05, 2018, 05:28:36 pm
content: Quote from: treez on August 05, 2018, 10:52:41 amYou realize that this reads like total bullshit, right? That it fails to recognize the reality of the trade, legislative and fiscal environment within the EU? That there is no such governmental entity as "The EU" capable of doing the things you suggest it is doing? And even if there were, the UK is inside the EU so such actions would apply just as much to the UK as to Germany, France or the Netherlands?

author: amyk
author_rank: Super Contributor
timestamp: August 05, 2018, 05:43:56 pm
content: One way to make flicker less perceptible is to increase the frequency into the kHz range. That also means smaller capacitors, and as such you might not need electrolytics.

author: IanB
author_rank: Super Contributor
timestamp: August 05, 2018, 05:47:59 pm
content: I think flicker is potentially very significant with moving objects like vehicles. Has anyone seen cars with LED tail lights that flicker like crazy when the car is moving? It drives you nuts. Imagine if that happened to every car driving under street lights?

author: Zero999
author_rank: Super Contributor
timestamp: August 05, 2018, 05:54:25 pm
content: Quote from: IanB on August 05, 2018, 05:20:48 pmWell if you read the rest of what I wrote, I didn't say it's impossible for a sodium lamp to emit any light, after the power has been removed.By the way, neither of the theories you've proposed, seem to be plausible. The capacitance between the electrodes will be tiny and the electrons in the plasma return to their ground state fairly rapidly. If you look at a mains powered neon lamp, the flicker can be clearly seen. The flicker from sodium lamps is less noticeable but I've seen some stroboscopic effects, in a car driving under sodium lamps. One thing I've noticed is the bars on a metal railing often become visible, despite travelling faster than the blur point.Quote from: amyk on August 05, 2018, 05:43:56 pmThe trouble is, if the lamp is running off a mains supply, there will be 100Hz ripple on the DC bus, which needs to be removed with a large capacitor, before the high frequency driver.

author: Gyro
author_rank: Super Contributor
timestamp: August 05, 2018, 06:00:31 pm
content: Quote from: IanB on August 05, 2018, 05:47:59 pmI thought I was the only one who got wound up by flickering tail lights!

author: ocset
author_rank: Super Contributor
timestamp: August 05, 2018, 06:37:44 pm
content: Thanks, yes and i agree with your sentiments...the point is that post brexit, being a middle man (for chinese imports into UK and beyond) will not be nearly so lucrative as it is now. (due to uk government tariffing the heck out of it)...the middle man mark-up will not be anywhere near as good.Hence a lot of companies will disappear.

author: james_s
author_rank: Super Contributor
timestamp: August 06, 2018, 04:07:47 am
content: I have some low pressure sodium lamps, I suppose I could light one up and put it near a photocell connected to an oscilloscope to find out if the output drops to zero.Incidentally, I found some years ago that instant-start electronic T8 fluorescent ballasts work very well to power LPS (SOX) lamps, I used a 35W one for several years on a Philips twin T8 ballast with both outputs in parallel.

author: Zucca
author_rank: Unknown
timestamp: August 06, 2018, 07:32:24 am
content: Thanks treez, it is always a pleasure to read your posts.

author: Kjelt
author_rank: Super Contributor
timestamp: August 06, 2018, 07:53:35 am
content: Quote from: treez on August 05, 2018, 08:41:55 amWe have talked about this before and your argument is false IMO.The problem is not the cost of the components because that would be true with drivers costing <$10-20The drivers you mention have a huge profitmargin for that company, BOM would be $15 but selling price triple even more when low numbers.So you have margin enough to design and build something.Where you will face problems is the following:- software:The software stack costed that company many manyears to develop and improve.Only a validated compliant DALI stack alone would be a huge undertaking as you have found out in the meanwhile.There are many so called SW engineers that have a 5 minute look at the spec and say oh easy.Talk to someone who actually has worked on it , and he will say: Oh my goooood DALI it is a snakepit of exceptions, holes in the standard and you need a testing facility to see if all masters will work with your slave, don't start on it unless you want to go crazy.Look at all the SW tunable options in these drivers, they can calculate when the sun goes up them selves just from the automated power on/off cycle from certain countries, those countries WANT that it is not an option it is an requirement. You can programm them to dim to certain levels automatically etc. etc.Look at the accompanying PC software , there are 3 programmers working 5 days a week on that alone.- hardware:Open one of those drivers up and see what is in it, about 200 components, believe me none is too much or they would have taken it out earlier with other costdown programms. The big manufacturers are also always looking to lower the price in order to better compete with the chinese.- thermal design:Elco's you need, so you need to design a way to keep them relative cool without melting the rest of the electronics, perhaps 20 pcb layouts to test the optimal one? Or copy it from the big manufacturers, the chinese do it so can you.- weather proof:Lightning protection, moist protection, go ahead build something that lasts 20 years, it is not that easy.Then margins and profit, look at the profit warnings from Signify (was Ph. Lighting) and their sales and you see the margins are evaporating although they have a lot of bureaucratic fat in their company burning profits.Many companies buy chinese drivers , they don't guarantee their product for 10 years anymore. The customer is the B-tester and the sucker to buy new stuff in 6 years or so, no-one cares anymore.It is tax money who cares, that is how people are thinking today and you need to adapt as a company or go belly-up.So that company buying those drivers probably with large discounts at large numbers is actually pretty smart unless they have an electronics+software+thermal+mech. design department summing of 20 or more persons currently eating out of their noses but I guess they don't.Do the math 20 persons 2 years and then how many drivers do you need to sell to break even ?

author: tooki
author_rank: Super Contributor
timestamp: August 06, 2018, 09:11:59 am
content: Quote from: Gyro on August 05, 2018, 06:00:31 pmOh you DEFINITELY are not! I’ve ranted about this on another thread here a while ago...

author: CJay
author_rank: Super Contributor
timestamp: August 06, 2018, 11:36:08 am
content: Quote from: tooki on August 06, 2018, 09:11:59 amFlickering tail lights, brake lights, direction indicators and those bloody VAG chasing indicators drive me nuts.

author: Kjelt
author_rank: Super Contributor
timestamp: August 06, 2018, 01:33:24 pm
content: Flickering or not, automatic gear cars waiting for a traffic light breaking continuously so the break lights blind you is a major PITA. They should dim after a few seconds IMO, when there is a need to signal upcoming traffic a small action would re-establish the full lights.

author: Nusa
author_rank: Super Contributor
timestamp: August 06, 2018, 02:47:53 pm
content: Quote from: treez on August 05, 2018, 09:18:28 amI bet if you stopped 10 members of the public on a busy street and asked them, 9 of them would have no clue what you're talking about. And the 10th probably would not be afraid of it.

author: ocset
author_rank: Super Contributor
timestamp: August 06, 2018, 07:01:51 pm
content: QuoteThanks, by "public", i should have said, i mean the ones who are in charge of buying public lighting...eg streetlighting....they think 100hz flicker is a killer...because they have read European Union regulations (EN 12464) which literally ban 100Hz flicker where the light goes to zero every 10ms…at least its banned for indoor use….due to the fact that it causes “headaches , tiredness and nausea”….i don’t agree, but it makes no odds what I think.The fact that its banned in this way means streetlight buyers simply wont touch it…even though they are outdoor lighting….its a total knee jerk reaction ,and totally without logical basis , but that’s the way things are.There are plenty of installed streetlights with 100Hz flicker going to zero every 10ms, and nobody ever complains about them...but this is the problem...once something is written into an EU regulation, the world stops in mindless abeyance of it.

author: In Vacuo Veritas
author_rank: Frequent Contributor
timestamp: August 06, 2018, 07:27:49 pm
content: Just admit you're trying to design a Close Encounters lightboard to get the Mother Ship to come pick you up.

author: chris_leyson
author_rank: Super Contributor
timestamp: August 06, 2018, 08:28:44 pm
content: BMW 5 series, for example, uses PWM do drive tail lights and brake lights to keep the apparent light level constant. Can't remember what the PWM frequency is but I was quite surprised to find it was quite low.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: August 06, 2018, 08:35:44 pm
content: Quote from: IanB on August 05, 2018, 05:20:48 pmTo indulge:1. Nah, no charge, it's a heated ceramic tube with ionized stuff inside, so the resistance will stay fairly low during a cycle (compared to cold resistance that is). So, microseconds there -- limited more by the driver transformer inductance or capacitance, say.2. Deionization time is definitely a thing. It's not a charge separation thing (the plasma is very nearly neutral at all times and in all places, except for thin boundary regions near the electrodes, if applicable). It's more of a thermal mass thing. Plasma is the "4th state of matter", though it doesn't have a sharp phase change as the other states do (it's not a first order transition, maybe not even a 2nd order transition, I'm not sure). Basically, it takes time for it to cool down, that is, for the ionized atoms to recombine and give off whatever energy they do (which for sodium lamps, happens to be a very large fraction of emitted 589nm light!).There are various factors for DI time, and I don't know much about it. Heavy ions and low densities tend to take longer. Example, low pressure xenon and mercury thyratrons are typically ~1ms. (Presumably, you can see the glow discharge dissipate over the same time scale. Hmm, I should give that a try.) Neon lamps, more like 100us. Hydrogen thyratrons, us to ns.Another way you can experience recombination time: sodium in a flame. A flame is hydrocarbon radicals and various intermediate combustion products, all emitting at various wavelengths (with the CH. and related species being the most notable, in the blue-green range, for low C:H ratio (gas fuel), neutral flames. Well, clearly those reactions are delivering a good bit of energy, if they're sometimes giving off blue light! Introduce some sodium atoms and they'll pick up that energy no problem. An ionic flame is also conductive, and, yes, it can even be used as a triode! Well, both the conductivity and light emission only last as long as the atoms have enough energy to do so, so you see a streak of bright orange glow in the flame, until it cools (or finishes reacting) enough to give essentially no more emission. You can calculate the flame velocity and see how long the sodium is (partially) ionized.Though this will probably give an upper limit (a relatively large value like 10s of ms), because all the other things are reacting much slower than the sodium atoms themselves.So, that's that.One could settle this very easily and certainly by watching the spectrum of the lamp under these conditions -- dollars to donuts, it goes from sodium d-line to black body (orange hot) when switched off.Another point in that favor: the afterglow looks damn like a thermal time constant (seconds, while nothing could possibly be storing that much electrical energy).Oh, hey, so, on a related subject, long-life phosphors are kind of like very slow recombination. Similar physics (well, hand-wavingly so), but in solid state instead, of course.There are actually a few gasses with very long transition times, like singlet oxygen (which emits at deep red / near IR), around 30 seconds half life when prepared pure, IIRC. This is possible due to spin transition rules prohibiting the singlet-triplet transition in molecular oxygen (triplet ground state), the lack of impurities with which to exchange those spins, and the slow reaction rate on container walls (because surface area is small compared to the volume). None of these are relevant to the contents of a sodium bulb, but if you don't know that, you're actually not at all wrong to suspect that it might be possible, because, in fact, it is; just that it's limited to much more contrived conditions and specific molecules.Tim

author: T3sl4co1l
author_rank: Super Contributor
timestamp: August 06, 2018, 08:50:10 pm
content: Quote from: amyk on August 05, 2018, 05:43:56 pmHeh, about that--Back when this was a hot story,https://en.wikipedia.org/wiki/Little_Box_ChallengeI chatted with a guy who was thinking about solving the problem with some combination of multi-level inverters. Well, that's fine for the AC output, but you still have to store the DC link energy somewhere, to meet the input ripple requirement (which, innocent as it seemed, on closer inspection, turned out to be about half the challenge of the design!). He brushed that off, which worried me... You simply can't violate the conservation of energy.So, you can PWM at higher frequencies, sure, but now it's pulsing at ~kHz, and you will find it's "tone bursting" at 100Hz. It's uh, not really helped all that much.You can at least make a few optimizations, give or take how much complexity you want to deal with.The winning design used a capacitor multiplier of sorts: a GaN bridge connected to an LC network, effectively the voltage on C is multiplied (via PWM switching) to make it look bigger. Energy is conserved, so for, say, 50V of input ripple, 400V of ripple appears on the cap. They also used a very boutique capacitor, an electret with built-in bias voltage, such that its C(V) curve peaks around DC link voltage (~400V) (whereas any conventional 1812 X7R chip cap you'll buy, is about 20% of nominal ratingor lessat that voltage!). The conventional alternative would've been an electrolytic capacitor literally the full size of their finished box!FWIW, C0G ceramics (if you can handle the price) and films (if you can handle the space) are some of the best on energy density, at high voltages (say, >> 200V). They compare favorably to electrolytics, but, they can be harder to use due to the much smaller values available, and the need for higher voltages.Tim

author: Gyro
author_rank: Super Contributor
timestamp: August 06, 2018, 09:25:31 pm
content: Quote from: chris_leyson on August 06, 2018, 08:28:44 pmThey had clever features in the past too. On mine, back in filament days, they regulated the lamp voltage (presumably PWM) and if a bulb failed the system would try to make up for the loss by using the next bulb to mimic it, eg. dimmed stop light for rear tail.No flicker in those days!

author: james_s
author_rank: Super Contributor
timestamp: August 06, 2018, 11:36:19 pm
content: Quote from: treez on August 06, 2018, 07:01:51 pmDude, we're here right now complaining about them! Get your head out of the sand, it's not a matter of fear, it's an absolute fact that some of us perceive the flicker and find it bothersome. What part of this do you not understand? Are you just hoping that if you say enough times that nobody is bothered by it that it will magically become true? You aren't bothered by the flicker, why are you so convinced that it isn't bothersome to anyone else? How many people have you surveyed to make this determination? It's not some invisible impossible to prove thing, put a bunch of light sources in front of me and I'll tell you which ones are flickering at 100Hz and which ones are not, I'd put a significant wager on getting it 100% correct.

author: Kjelt
author_rank: Super Contributor
timestamp: August 07, 2018, 06:36:58 am
content: Just to make sure do you know for reality it is the100Hzflicker you have problems with?Al the TL (tube lights) and Sodium pressure lamps on conventional ballasts were 100Hz (120Hz in US) and no-one complained about them till they were EOL.At that point the cathodes of the Sodium lamps and the filaments of the TLs are worn and you get sub-100Hz flicker which indeed is very annoying.Modern electronic drivers use around 400Hz frequency AFAIK.

author: tggzzz
author_rank: Super Contributor
timestamp: August 07, 2018, 07:06:59 am
content: Treez starts threads in which his company is having problems with the reliability of SMPS in a remote (Balkan?) outdoor installation, "his friend" is condemned to not follow his career of choice (building SMPSs), and 100Hz anti-flicker specifications are a "scare tactic" for "no sane reason".Common themes are that measurements are suggested but not made, and that outside forces (technical, commercial, political) are preventing him and "his friend" from going down their chosen path.I think treez should look inward, and would have benefitted from being taught by Prof Eric Laithwite at Imperial College. Why? On principle in the final year exams he set for undergraduates, he would include three types of questions:one question could be answered by everyone that had attended and understood his lectures - sufficient for a pass degreesome could be answered by people that had explored beyond his course material - sufficient for a first class honours degreeone couldn't be answered in the time available - and should be avoided at all costsand he expected that hisundergraduatescould determine which was which and avoid the impossible question. If they couldn't, then they deserved not to get good marks because they probably wouldn't be successful engineers.

author: Kjelt
author_rank: Super Contributor
timestamp: August 07, 2018, 07:19:02 am
content: Quote from: tggzzz on August 07, 2018, 07:06:59 amIn his defense this is probably his first or one of his first jobs and he ended at a strange company claiming to be A but acting like B.Many small companies have their quirks and he is probably better off with a somewhat larger firm that have enough people to get help and support from esp. when the bosses are a bit clueless on their technology capabilities and what it takes to build something that seems so simple.Although outdoor lighting seems relatively simple, it is not, there are many standards to adhere to and they often differ per country.Then there are these horrible conditions of the offered mains that fluctuate and induced voltages on the control lines and you can go on and on.Big companies can also get burned by these things and have to replace 1000 fixtures in some hoolaboola country they underestimated. For those big companies that is a tax write off they easily can survive, small companies can go belly up on bad projects like that.

author: tggzzz
author_rank: Super Contributor
timestamp: August 07, 2018, 08:46:29 am
content: Quote from: Kjelt on August 07, 2018, 07:19:02 amAll understood and accepted. In particular I'm sure the points about mains and regulations are accurate and relevant.My statements, which are obviously very much a precis and can therefore be inaccurate in various ways (especially "by omission") are based only on what I have read here. I have no other knowledge of treez' background, situation, and future options. Consequently, while I do have some sympathy with him, I can't offer concrete suggestions for his future - only he can do that.Having said that, I do think his approach to problem solving (as visible on this forum), could be improved. I also think he needs to find a way to take a "step back" and think about where he wants to be in the long term. That is often difficult when faced with short term pressures - but everybodymustdo that occasionally.Repeatedly trying the same thing and expecting a different outcome is something softies tend to do more than electronic engineers

author: Kjelt
author_rank: Super Contributor
timestamp: August 07, 2018, 09:26:55 am
content: Agreed, I also had some questionmarks about him asking professional work related questions on a public forum.Sometimes it might be ok'ish esp. when you don't have colleagues with the same line of work and you like a 2nd opinion.Since the information is retained "for ever" it could become an issue in the future. When I was a student in 1996 I asked a question online in a electronics newsgroup, you can still find it under my name, that is quite weird.

author: bob225
author_rank: Frequent Contributor
timestamp: August 07, 2018, 09:31:15 am
content: Quote from: Kjelt on August 06, 2018, 01:33:24 pmot. Imho that is down to bad/lazy driving practices, If your stopped for more 20-30 seconds drop it on Neutral or park

author: CJay
author_rank: Super Contributor
timestamp: August 07, 2018, 09:54:44 am
content: Quote from: bob225 on August 07, 2018, 09:31:15 amMy partner's car helps create those lazy practices, it automatically puts the handbrake on when you stop but it does mean the ridiculously bright brake lights don't dazzle people

author: Kalvin
author_rank: Super Contributor
timestamp: August 07, 2018, 10:07:09 am
content: It is still surprising me after all these years that Treez has yet to revere-engineer any of the competitors' products and take a look at how the things have been done in products that are sold to customers and actually work.

author: Jeroen3
author_rank: Super Contributor
timestamp: August 07, 2018, 11:41:49 am
content: Quote from: Kjelt on August 06, 2018, 07:53:35 amInteresting... Do you have more info on this?Quote from: bob225 on August 07, 2018, 09:31:15 amThat cars creep forward when releasing the brake is also deprecated. Start by fixing that.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: August 07, 2018, 12:12:36 pm
content: Quote from: Kjelt on August 07, 2018, 07:19:02 amI think he's been in more or less the same field for about a decade now, changing jobs at an average turnover rate (a couple years?). It could very well be that he's only found companies that meet that description, or that he's been at the same one all along and neither management nor their employee(s) (or at least just the one) realizes what they want to do, and how.We owe this curiously long experience to OP's affinity for online forums, at least three over the years I'm aware of. Always seems to keep popping up.Tim

author: Kjelt
author_rank: Super Contributor
timestamp: August 07, 2018, 12:14:01 pm
content: Quote from: Jeroen3 on August 07, 2018, 11:41:49 amWhat exactly ?The configuration software differs per manufacturer, Philips now called Signify has the MultiOne tool:http://www.lighting.philips.co.uk/oem-emea/products/philips-multione-configuratorFor the dimming it is software, depends if the driver still has power like with Dali it can then calculate by the on off commands how long it is dark and find the right time spot to dim (as configured). With hard on off, normally the streetlights are turned on automatically from a central control when it becomes dark, fixed programmed for the year and turned off when it becomes daylight. So software knows how many hours it is on , stores this information for a couple of cycles in NV memory and from a few cycles it can calculate what period in the year it is at and start to dim according to the programmed configuration. It works something like that.

author: tooki
author_rank: Super Contributor
timestamp: August 07, 2018, 12:51:58 pm
content: Quote from: treez on August 06, 2018, 07:01:51 pmWhat an astonishingly arrogant attitude: “I am not sensitive to flicker, therefore it’s a silly non-issue by EU bureaucrats.” No, those rules came to pass due to real issues by real people. It can be measured, and a certain percentage of people are more sensitive to flicker than others.Do you take the same attitude towards, say, allergies? “I’m not allergic to peanuts, therefore peanut allergies are a lie!”Quote from: Kjelt on August 07, 2018, 06:36:58 amExceptthat’snot true, either! Plenty of people complained of issues from traditional fluorescent lighting.

author: tggzzz
author_rank: Super Contributor
timestamp: August 07, 2018, 01:19:55 pm
content: Quote from: T3sl4co1l on August 07, 2018, 12:12:36 pmThat raises a generic question that treez might like to ponder....There are two approaches to a career:be a jack-of-all-trades and master of nonebe a world expert on some topicThe former has the virtue that it tends to protect from the worst changes in the job market - but you are more expendable/replaceable.The latter has the virtue that employers know you are unreplacable and valuable - butonlywhile that topic is of interest to employers.Either choice is valid and down to personal preference - but one way or another a choicewillbe made!QuoteWhile there can be good valid arguments for anonymity, in a small field it can be difficult to remain anonymous.

author: jancumps
author_rank: Unknown
timestamp: August 07, 2018, 02:21:11 pm
content: We don't know until the discussions on that stabilise. Whatever happens, I bet that the impact on switch mode module production will be neglectable.

author: Kjelt
author_rank: Super Contributor
timestamp: August 07, 2018, 02:38:48 pm
content: Quote from: tggzzz on August 07, 2018, 01:19:55 pmI wonder if this is still valid for electronics / software / any tech job.To become a master in any of these fields in a company in this day of age you have to look ahead and learn yourself topics that are not so hot but are becoming hot. And have the ability to pick the right ones from the ones that never get the attention. You have to have the knowledge and experience just before companies are getting interested, in the meanwhile performing top notch in your current role.That is not so easy anymore. I sometimes say to my partner who is a college educated nurse on a cardiac department, that if the human heart (body) would change as fast as the electronics/software field you had to re-study the total anatomy since you would have an alien body instead of a known human body.

author: james_s
author_rank: Super Contributor
timestamp: August 07, 2018, 03:27:12 pm
content: Quote from: Kjelt on August 07, 2018, 06:36:58 amI don't claim to be able to tell the precise frequency just by looking at it, but I can absolutely see the flicker even with a fairly new lamp. Actually 100Hz stands out quite a bit more as it's not what I'm used to. When I visited the UK I found the lower frequency to be quite prominently visible in all types of discharge lamps. After I'd been there a few days it was less noticeable but the first night it was like whoa, flickery! The brain is able to tune it out to some degree, but when it's suddenly a different frequency than you've seen your whole life it's very visible. Lighting is something that has been a strong interest of mine my whole life so lights are something I've always paid attention to wherever I am.

author: james_s
author_rank: Super Contributor
timestamp: August 07, 2018, 03:33:19 pm
content: Quote from: Kjelt on August 07, 2018, 09:26:55 amIt's one thing to ask professional related questions in a forum, it's quite another to ask them at every turn, relying entirely on the forum in order to do one's job.

author: Kjelt
author_rank: Super Contributor
timestamp: August 07, 2018, 03:38:21 pm
content: Quote from: james_s on August 07, 2018, 03:27:12 pmOh I am sure that a small part of people are more susceptible to the frequency as others.For instance with DLP projectors the images are seperated in different primary colors and projected sequentially over a mirror device and a rotating colorwheel.Some people don't see it while others go crazy with headaches.All I am saying is that with fluo which was developed before WW2 there were relatively little complaints, whole generations grew up with them in schools and workplaces.It helps that the plasma and phosphors kind of buffer the lightstream so the flicker is medium to low compared to Leds that are notorioys for fast on/off response.So yes best is to dim leds with current and not pwm also for emc purposes.Quote from: james_s on August 07, 2018, 03:33:19 pmI agree. I initially thought that Treez was a beginner but reading previous posts from other users and seeing in his profile he is 39 that sheds a different light on the matter.

author: tggzzz
author_rank: Super Contributor
timestamp: August 07, 2018, 03:42:47 pm
content: Quote from: Kjelt on August 07, 2018, 02:38:48 pmIt was never easy, always required work at home, and was always risky!It is always necessary to be able to discern the frothy changes from the fundamental changes. Hence I ignored froth such as Delphi, Modula, C#, and web GUI frameworks. Concentrating on C, Smalltalk and Objective-C and then Java (and understanding first-order predicate logic and FSMs) was a good set of choices!

author: james_s
author_rank: Super Contributor
timestamp: August 07, 2018, 03:49:40 pm
content: Quote from: Kjelt on August 07, 2018, 03:38:21 pmI don't find the flicker of fluorescents to be objectionable in most cases, it's subtle but I can certainly tell that it's there. I think the persistence of the phosphor softens the edges and the light doesn't drop all the way to zero. Flickering LED lamps I find extremely annoying though, I've never tried one on a 50Hz supply but even on 60Hz the flicker is very visible and distracting.

author: IanB
author_rank: Super Contributor
timestamp: August 07, 2018, 06:17:02 pm
content: Quote from: james_s on August 07, 2018, 03:27:12 pmDoes that also apply to sound frequencies? For instance, if you are in the UK does the transformer hum stand out as being different from the USA?

author: IanB
author_rank: Super Contributor
timestamp: August 07, 2018, 06:18:35 pm
content: Quote from: Kjelt on August 07, 2018, 03:38:21 pmMaybe Treez has been a beginner for 20-odd years? He certainly has had a lot of practice at it...

author: james_s
author_rank: Super Contributor
timestamp: August 07, 2018, 07:47:54 pm
content: Quote from: IanB on August 07, 2018, 06:17:02 pmYes, that also jumped out at me, transformers, refrigerators, all that sort of stuff sounded weird. My friend who lives over there has said the same thing about visiting the US, for the first day or two electrical equipment sounds weird, but then you adjust and it's not as noticeable. A bit like if you sit in a room lit by colored light after a while it starts to look white.

author: tggzzz
author_rank: Super Contributor
timestamp: August 07, 2018, 08:17:40 pm
content: Quote from: IanB on August 07, 2018, 06:18:35 pmThere's the old point about there being a difference between 20 years of experience, and 1 year of experience repeated 20 times.

author: tooki
author_rank: Super Contributor
timestamp: August 07, 2018, 09:14:54 pm
content: Quote from: IanB on August 07, 2018, 06:17:02 pmI can’t say that I noticed that when moving from USA to Europe. But what I definitely notice is content shot on film at 24fps is sped up to 25fps for PAL - I hear the 4% speedup. (Mercifully, with modern digital distribution, both disc and streaming, this is finally going the way of the dodo.)