Sudden science - driving fluorescent tubes properly.
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- เผยแพร่เมื่อ 31 พ.ค. 2024
- The humble fluorescent tube is an absolute minefield of science. Still a very valid contender to LED, it's a long term proven lightsource with good efficiency and reliability.
Here's a small taste of the science involved in driving them properly for maximum lifespan.
This video explains the very basics of driving them properly, but in almost 20 minutes it barely scrapes the surface of the history and technology behind this type of lamp. But it's a good starting point for further exploration on the 'net. - วิทยาศาสตร์และเทคโนโลยี
This the best and most thorough explanation of how fluorescent lighting systems work I've seen on TH-cam so far. I couldn't find a single error - well done! Also, thanks for putting the mercury fear-mongers in place. :P
Yeah it anoys me when people talk crap about Mercury light sources
Exactly, I recall in my freshman year High School Earth Science playing with Mercury as a curious metal that had many wonderful uses. That was back in 1966 or so I guess so not as much was understood about the "danger" of Mercury. Seems we came away unscathed even though we were mere inches from that dangerous fluid metal.
I remember doing stuff in A-level chemistry, in the late '80s, with mercury. I also remember that my gran had a few hand-held maze games that used mercury instead of a ball bearing.
The danger from mercury is if you're exposed to it regularly, and not occasionally like most people, or if it gets into your body (contaminated food/water). Even then it'll take a while for anything to happen.
People fail to realize our kidneys and liver are pretty efficient organs. Always giggled when people get up in arms about minor exposure to mercury yet ignore gasoline and smog...
I've heard low molecular weight, organic mercury compounds are the stuff to avoid.
Excellent explanation. I think a LOT people don't understand the difference between rapid, instant and preheat start. Instant start was one of the worst things to hit the industry and I have no idea why they were even allowed. I have been ripping out instant start ballasts when I can and replace them with programmed start or rapid start. Best ones are where they have instant start ballasts on motion sensors. Needless to say those lamps are tortured quite badly.
Still can't beat a preheat lamp with a simple choke ballast and starter for efficiency and reliability.
In old fittings we had at work, there was a metal gear tray, but the shade was plastic and was the cover for the gear tray, this is going back to bayonet holders and terry clips.
So the earth was bad near the tube, but the original tubes had a metal tape along one side that connected to the metal bayonet holders.
Replacing the tubes we found some bayonet to 2 pin adaptors, then used some aluminium foil (the type that is used on windows for burgular alarms) to make the earth strip.
the quick fix for a shorted starter was to twist it back and forth to get the light working, then remove it, and at some point in the day wwe changed the tube and starter because the tube would have deteriorated enough that it wouldn't last much longer.
btw, they wanted a very visible flashing light at work to indicate that the freezer room door was open, i used a 40w starter in series with a 40w lamp, worked great for years :D
People don't explain fault situations like this often... fucking great stuff man... I appreciate it, I'll have to watch it again and take notes.
Edit: I need more of this stuff... this is awesome.
Also worth pointing out that the metallic mercury vapour in flourescent tubes is a great deal less harmful than organic compounds of mercury, which is the really nasty stuff that requires very little exposure to cause serious health effects. Most people don't understand the difference.
Great video with lots of information. I love gas discharge lamps and am sorry to see them being phased out in favor of LED, even when in some cases there are few benefits.
Hi Clive, I’ve had to deal with all the problems you mentioned over many years & when i was an apprentice i loved working on fluorescent signs & fittings but none of the sparks that i worked under understood how they worked or could explain to me what went on.
I used to dismantle the old fittings to find out how they worked - later on when i worked on many TV Rental shops i would supply & install hundreds of feet of back light fluorescent tubes to the shelving that ran around the shop - at the time it was very futuristic.
I still like fluorescent problems & can deal with them all when called.
Edward.
Good stuff!
+Applied Science That's a super-compliment from you Ben. I admire your technical skills greatly.
+bigclivedotcom you guys should do follow ups on each other's video's/topics.i would love to see Ben's version of playing with lighting technology like this. and Clive's version of some of the mind bending stuff he does. "applied science; narrated by a guy with a beard."
+bigclivedotcom what is the thinnest fluorecent tube made ever
+dannyjaar Hot cathode lamps go down to around T4 (half inch) diameter, but they go down to very small diameters in the cold cathode style with one electrode wire at each end. They can make them around 1mm diameter for specialist applications.
+THE VERY BEST OF TH-cam
It's insane...they are planning on outlawing every single type of incandescent light source, down to the tiniest pilot light.
Thanks for a fascinating video which makes me feel a bit more comfortable about what I did in the 70s when we in UK, suffered the now historic Power Strikes leading to the 3 day week.
I was not fiddling with tiny tubes but full 4 foot or 5 foot tubes.
I was further hampered by the fact that I didn't really know WHAT I was doing.
This CAN prove to be a bit of a disadvantage.
I built a two transistor inverter (2N3055) much in your skeleton circuit with cross collector-base feedback. 12.5 vdc
I guessed that there was need for a heater voltage at each end and plenty of EMF from end to end.
In those days, old TVs could supply ferrite cores from cannibalised, line output/EHT transformers. One transformer supplied 2 cores for this job..
I got the LT winding turns from a circuit for an HT inverter for a ham tx.
The over-wind was a "that looks enough" exercise, although it wasn't... and trial and error
played a major part. The same applied to the heater winding but I eventually lit 4 and 6 foot tubes.
Some interesting things emerged from this.
If the system set off on a fully charged car battery, no apparent reduction in light output
occurred until the batt volts dropped to 8 or 7 volts or lower. But don't switch it off or it won't start again until recharged!
The waveform interfered with MW/LW radio just as much as it did when the ferrite
was inside a mono-tv.
Couldn't make them fast enough during the 3 Day week.. Never made another when it
stopped!
I worked out that it was running not at 50 hz but 6/7 Khz..
I was later informed that running at higher freqs produced more light for a lower DC. consumption. Working, not scientific tests showed this to be so.
Who informed me of this and other aspects?
Raymond Baxter on Tomorrow's World with an item in his show relating to this break through that scientists had made for energy saving....two and a half years later.
Thanks for the mention Raymond!
Appreciate you explaining failure modes.
Great video. You're very good at explaining this stuff, so that even guys like me without any more electronics knowledge than what you learnt in high school can understand what you're basically saying. And it's not always easy to be an expert and explain things clearly to a layman.
I really learned so much! Thanks so much, Clive. I knew I knew nothing about florescent tubes, and never got around to learning. I'm chilling at home waiting for the missus to come back from visiting a friend and your new videos made me afternoon great!
@bigclivedotcom
A friendly tip to make these tubes last longer in old school ballast fittings.
You mentioned that as the filament gets worn, the ends starts to flicker. I dont replace them but instead the tip is to then rotate the tube 180 deg in the fitting. Reason is because the filament is actually most run on ½ the filament side (more or less, because of shortest route), so by rotating it, u can lengthen the life by switching to the other side. It will lower the voltage need again and give the tube a little more time.
Best way is of-course to do this on regular basis to even the load for maximum lifetime, but as long as u do it just as the flickering starts (and are not bad already) u can get several months worth of extra use of the lamp itself.
Another tip is to always remember to "burn in" the tubes, as in leave them on non-stop on first time use. This especially on the newer T5 tubes, to even out the mercury vapor. T5 14-28W tubes for ex need 100-200h burn in normally, for optimal lifetime. T8s usually u can get away with 50-100 dep on size. This makes the light even from the tube, and lengthens time before it fails. This also goes for compact florescent tubes as well.
Thanks Clive for clearing up a matter that has had me wondering for many years. I've been using various methods of 12 volt lighting for most of my life. There was one particular type of 12 volt fluoro lights that I bought, where the tubes only lasted a couple of weeks to a month with daily(or nightly) use. I now understand why. It was a double fluoro with 2 x 8 watt tubes driven in series. The circuit itself didn't look much different visually to that of a single 12 volt fluoro. Obviously, it must have driven them quite hard. lol. It was a bloody bright light too, it's what disappointed me when the tubes died so quickly.
Wow Clive. You've come so far in four years!! Your presentations are so much more slick now. Well done!!
The best easiest to understand video on Fluorescent lighting I have ever seen.
50+ years working in electronics and I never knew how a floro tube started. It's a bit embarrassing but then I never really needed to know. Like so much we just take it for granted.
Thank you for that.
Finally! An explanation of that bloody flicker which drove me crazy in school!
Probably one in five of my classrooms had a spot where the tubes were showing the 50Hz flicker and it would give me a splitting headache which nobody else could seem to see.
Nice video. Merry Christmas!
In my fledgling Electronics Geek days I took a 12v relay and wired it so when the coil pulled the contact in, it disconnected the coil and when it returned, it pulled in, essentially a mechanical oscillator. Fed the connections across the contacts into a step up transformer and the output of the transformer into a 4' florescent tube with the filaments wired in series. Amazingly, it lit the tube. I know there are so many reasons this isn't a good idea, but I look at it as a learning experience. Many years later, you explained how they are supposed to work and why.
Rich Booth even i had this idea but didn't get confidence to do the work
@bigclivedotcom
I am an electrician from Sweden and I do appreciate the topic and I do understand what you are talking about. I think the Starter you mentioned during the first start-up is the 'Reactor' as proper term. Non-electricians call it Glimmtändare though.
The second circuit, I have not really seen. Maybe I am too young to really see them since Energy efficiency in light and the ergonomics of it is fairly big subject in Sweden both for us electricians and those that project(Plans bigger jobs). So it is generally either two different topics of subjects regarding starters now days.
It is the Reactor and it is the HD-reactor. The latter being the electrical version. On the topic of light bulbs, both business and electricians in general tend to recommend you burn the tubes in for roughly 1k hours for the best light. Obviously not a topic you bring to a private customer that won't appreciate paying such electrician bills but I thought it was interesting to enlighten you.
The reason, I am not really sure but I assume it has something to do with the gases within the tube along with the potential Mercury vapour to settle into its environment and get used to the equipment.
But this is hardly the focus for Electrical. The advantage lies in the shifting of the Sinus curve. The faster the shifting, the less load on the bulb but also better for individuals in general whom work under this light. You said one could see shimmering/flickering. Technically, you can still see this on a good bulb as well if you have good eyes and science has proven that 60hz is a reason many people in office environments etcetra suffer headache and lack of ability to think since the brain unconsciously notices the shifting light that seems constant to you and therefore uses a bit of brain process for that part. How ever, once you exceed a couple of thousands, I think it was 5-6k hz the brain simply stops thinking about it. Many people seem to work better under such high speed frequencies. Oh, a warm light is also generally a colour to not use in office environments as well. Cold light produces less depression like effects.
But out of company aspect when creating these electrical circuits, you generally want 10k since it is easier to calculate and construct money wise. Don't ask me why but perhaps because it is an even number and they can limit the electrical parts? Ah well. Now, it comes to a topic that is generally a discussion between electricians in sweden and customers. Both private and business alike, it is when it comes to the HD-reactors themselves.
On certain brands and models, the HD-reactor dies quickly and on some it doesn't, generally the reason is price and where they bought it from. While everything else is fairly simply and straight forward, it might be a cheap China brand which is known to be a bad product in Sweden. We have highest electrical standards in EU to my knowledge. I wonder, what you think is the reason why some HD-reactors burn out quickly while others don't? IS it potential damage in shipping or handling? Or is it simply product deficiencies?
Also, for LED, you should preferably don't use them in bulb form on a location where you work under many hours. They generally do not offer good long term effect on your eyes. Although you might not process it, your brain will process things unconsciously even for LED. I suggest simply buying an overpowered Light fixture and simply dim it down. Lengthens the life of the bulb and improves general long term effects. Especially good for detail work where LED is simply inferior still. LUX being the reason to my knowledge. LED has too much, direct light in comparison to normal fixtures is my theoretical reason also something to do with colour but that is beyond my ability to comprehend.
Either way, long rant but hope it was an interesting read.
EDIT; LED is useful in colder environments though, it is fairly easier to start up in lower temperatures.
Regards.
Great video!
I'm glad you mentioned the need for a grounded reflector with some bulbs. I discovered this one morning at work (broadcast engineer) when the background lights in our TV studio weren't working. I took the trouble call, grabbed my DMM and a screwdriver and went to see what was wrong. There was about twenty 32 watt lamps and none were working. The voltage into the ballasts was OK. Thinking that the bulbs weren't seated properly, I grabbed a bulb to remove it and it lit up! Each bulb lit up as I touched it.
It turns out that an audio engineer was troubleshooting some hum issues had disconnected the ground wire to the set.
I had no idea there was so much to these little buggers, cheers Clive
Funny, he mentions vehicles at the end and that is actually what came to my mind while I watched the video.
- You are a great teacher ! I wish i had a teacher like you...but i had (and still am) learning by myself all that i know. I love how you exemplify and argument.
What a great Christmas present, Clive. Yet again learned a lot!
Than you Clive for explaining this "rectifying effect" I always wondered why tubes that are at the end of their useful life sometimes go into 50Hz operation!
Thanks, we value the time and effort you spend for this channel
Even as a engineer in the lighting industry it's interesting to have this explained. Thanks.
older vid i know but commenting anyways. this basically perfectly explained what was wrong with my bathroom light where I had no clue how to fix it. liking these videos more and more, so much learning :D
This is a very thorough and explanatory video. I'm not sure what the UK standards are, but here in North America our fluorescent lighting systems utilize a special transformer called a "ballast." There are two types of ballasts: magnetic and electronic. Magnetic ballasts are essentially a choke connected in series with a starter, although newer magnetic ballasts often have built-in starters. The only downside to magnetic ballasts is that they generate A LOT of heat, especially when left on for more than 6 hours a day. For this reason, many magnetic ballasts are equipped with thermal protection so if they should overheat, they will shut off and restrike once the fixture has cooled down. However, this isn't always the case, and older magnetic ballasts were sometimes blamed for starting fires. There also have been instances where the thermal protection has failed, causing the unit to become dangerously hot. In 2013, the government "phazzed out" the manufacturing of magnetic ballasts.
Electronic ballasts are much safer and more efficient in the long run. In fact, many modern electronic ballasts are instant-start and capable of driving 2-pin tubes. I have some in use and I've noticed that the tubes are "sputtering" much quicker than with the old magnetic ballasts. There is another alternative, a programmed-start electronic ballast, that starts the lamps in the same manner as the previous magnetic ballasts. These are often a bit pricier and may be somewhat difficult to come across, although they do not "abuse" the lamps like the instant-start electronic ballasts.
By the way, mercury is NOT dangerous! The government overemphasizes safety when it comes to handling fluorescent lamps. I have shattered many fluorescent tubes, including a shattered CFL in my den. Not to mention I also played with mercury when I was only 6 years old...
Thanks so much Bigclive! You're a great teacher/host/explainer!
You make every subject, even the humorous bits, fascinating and fun.
Thank you for the awesome video :) The videos you make are always packed with so much valuable info. I have watched so many and actually learned something that i still remember and use so often in everyday life. So Thank you, you are doing a valuable service and should be commended on it!
Thank you. That was an excellent introdction. The books normally just explain what you should do but do not expose the consequence of not doing it the recommended way.
Thank you for taking the time to make this video - I thought I was the only fluorscent tube nerd on the planet.... :-)
All these years sat not interested in school work and staring at the florescent tubes makes sense now
CLive, i used to repair the 24v lighting ballasts used to light up tubes in coaches and buses, it was part of being the electronic repairer of an auto factory.
The transformer with heater supplys was the exact way the ballasts worked, they operated at 20khz and a push pull two transistor symetrical oscillator with feedback windings and identical components was the way it worked.
They worked really well :-D
Your discription is spot on, no supprise there :-D
When I was a boy, a school friend invited me to a party at his house. His father was the caretaker of a Decca Navigation Station (used by commercial aircraft for navigation in the old days). He Handed out fluorescent tubes to us all, and we went out and danced about round the transmitter mast. The tubes lit up in our hands. We were very impressed!
Excellent video! No idea why I didn't see this in December!
I had a few sets of these T5 (maybe they were T4?) in varying lengths as under-cupboard lights in the kitchen; some daisy-chained, all 240V... The tubes "blew" with alarming regularity (at least one every 6 months!), and unlike the larger T8, the fittings didn't have a separate ballast / starter. Almost every time I visited the *same* local shop to replace the tubes, they ended up being a different manufacturer and slightly different dimensions (actually within a year or two even THE SAME manufacturer, had different dimensions too!) with each tube being a few mm shorter or longer... So not only were tubes replaced, but the fittings were too...
I gave up the last time - and instead purchased some LED strips and 12v transformers, which I have fitted. They give far better light, show no signs of becoming unstuck, are run cooler and use less power.
The T8s in the garage I also replaced, but with "replacement LED tubes" - which also replace the "ballast/starter" with a LED compatible driver - so are "drop-in" replacements.... Oh - the joy of "instant light" in the garage. :)
+Sean Pearce Quality T5s are supposed to give LEDs a run for their money on lifetime.
Great topic, man I know a lot about this but it is always good to get e refresher on it.
When I was a much younger lad (1963) I had a television transformer that had, I believe a 750v winding. I took a 40 watt tube and powered it on, albeit very briefly, with said Xformer. Talk about a flash tube... It blew the mains fuse and all I could see in the dark basement was the retinal burn of that lamp. The lamp was now ALL black and made plinking sounds when shook.
Ballasts are very unique devices and you are correct that the topic gets going on to know about them all.
An electrical engineering text I had, spoke to the development of specialized high frequency gen sets for office buildings fluorescent lighting that would have yielded more lumens per watt.(over 50 or 60 Hz) I do not believe this was a commercial success. Fast forward 5 decades and the compact fluorescent is indeed a marvel of efficiency
BTW
Merry Christmas Clive
+Craig Nehring The old TV transformer may have been an auto transformer with the higher voltage referenced directly to the mains. That way, the high voltage would strike the tube and it would then try to crowbar the mains.
+Craig Nehring I am glad you mentioned that, I'd forgotten they tried to run at HF. Weren't they 400Hz? (that way transformers would have been readily available from the aerospace industry)
Pretty sure that transformer secondary was isolated and just dumped the full output across the lamp, then again it could be as you say.
It was all over in literally a flash.
Back in my early experimental days I would try and run things backwards, for example using an electric model train transformer I would output that low voltage AC into the various winding's to see what voltages I could get.
One thing for sure there was a substantial current flow through that lamp.
Cheers
*****
Aircraft do run at 400Hz for good reason the magnetic cores can be smaller and lighter, not sure what freq they had hoped for on the genset in office buildings but the CFL I believe is running at 10kHz.
Most aircraft also use 28 VDC for the same savings, wire capacity is thinner and motor are smaller. Aerospace hardware is very spendy: certification, regulations et al.
I used to do component overhaul on some Lockheed and Airbus craft.
Confused...? 21 years since I have been involved with electrons, professionally, but surely the lower the volts the higher the current requiring more copper. ? Higher the Hz higher the impedance, good, less copper. ?
Super video - you give others too much credit. I never found anything nearly as detailed as what you just went thru. Thanks for the share.
I love the way you describe all the failed design to strike the tube.
As it turns out the newer state of the art driver is called a "Programmed Start"... it makes the tube last 20Yrs with unlimited On/Off cycles - Lots of ballast manufacturers make them, easy to buy on eBay.
Basically these ballast glow the filaments before striking them On with HV, then gradually power down the filaments as the tube keeps runing - No more black ends, endless life: Perfect!!!
Very Interesting Subject Clive. Awesome Video. Thank you. Keep up the great work. Nick.
Realy interesting video, nicely explained.
I have changed probably 1000's of these tubes and rapaired 100's of amaturs in my aprentice time, but never have i sat down to try and understand what made these lamps work.
Now i know, it is super simple. :-)
Thanks a lot.
Morten
Real good video. Thoroughly explains why my 12V floru drivers i built 20yrs ago is still going strong, yes the filaments at both ends also driven with low voltage, the extra windings on the TX as you show. Additionally used another current sensor Tx for f/b. Used a 555 to drive a mosfet.
Some of this was over my head, but still very informative. I've seen all of the problems described, and now I have a better understanding of what causes them and how to address the problem. Thanks!
Once again, another amazing video to learn loads of information from. I can't watch one without learning something to help me with my projects. I have to say, this is likely my favorite channel on youtube.
I have always found fluorescent tubes mysterious. I now have a better understanding of them. You are a good teacher! Thanx,
Wow that video was packed tight with information and very well structured. You certainly know your fluorescent tubes, Clive. Lot's of interesting physics going on there.
Hey BC, ever play with "No Cathode" fluorescent tubes? They last centuries. Or, about 25yrs in continuous operation. Eventually the phosphor starts to dim out. With no electrodes inside to trap gas ions or sputter a black stain, the main failure mode is removed. The commercial type is the Induction Bulb, about $30 on eBay.
Or, make your own 1890s Nikola Tesla-style bulb by wrapping adhesive foil rings around the tube ends, placed on the glass a bit forward from the filament location, positioned so the plasma doesn't touch the unused metal parts inside. Attach a CCFL driver to the two foil electrodes (use those little 2-transistor drivers found in cold cathode LCD backlights.) A small conventional tube will light up full brightness. No electrodes, at least not inside. Watch out though, since the drive is about a kilovolt, and any sparks can be a burn hazard!
When CFL spiral-bulbs were first announced in 1974 Popular Science, they said they were going to be powered capacitively by high-volt 27MHz, lack electrodes, and last for over 100 years. Then, nothing. No peep about them for years. When they eventually appeared, they weren't like those glass-capsule electrodeless "RF lamps" being promised. Instead they were just conventional fluorescents, but bent into a spiral. And, still employing the interior metal electrodes which get destroyed after a few years of operation. True "RF lighting" does exist, and it lasts far longer than HID, longer than LED. Not sold in stores everywhere! Buy it now, NOT!
We can get the fluorescent forever-bulbs from offshore suppliers via eBay. Still, those have an induction loop coil and expensive ballast driver circuit, and a torus-shaped glass globe. Not the simpler capacitive coupling done by metal rings outside the glass.
Oh, and about "mercury freakout?"
This used to be a real issue back in the 40s/50s when lamp internal coating included BERYLLIUM OXIDE, and the white dust from a shattered lamp was carcinogenic toxic inhalation danger. Not the mercury. People in the early-1950s factories were dropping like flies from beryllium poisoning, corporate coverup, big scandal. And everyone was supposed to leave the room if a tube shattered, until the BeO powder could be washed up. But then toxic fluorescent powder was replaced by other materials.
Yet everyone for decades later still goes crazy when a fluorescent tube gets broken. Very silly. But we can see where it all comes from, as the older "dire warnings" get passed down the generations, even though the lethal hazard was removed fifty years back.
+wbeaty I have played with the electrodeless lamps. In fact I burst a full-price expensive one when they were new while trying to open it. :( There was a company selling DIY neon signs for a while that used electrodeless letters that clipped onto a high frequency exciter backplane. I also recall that my first EPROM eraser had a totally sealed tube which got its power capacitively coupled from two ordinary fuse clips. Then there are those intriguing linear lamps that are basically based on xenon tubes, and have one electrode at one end and a clear conductive coating.
At the Edinburgh Tattoo we switched to using induction lamps for the house lighting. Fast warm-up time and low enough power to run on a battery powered backup system so we have full output in the event of power failure.
+wbeaty the mercury tubes do severe damage on submarines, long ago when I was in navy they had florescent tubes on subs and it killed one entire ship one lamp breaking. nice to know about the beryllium, thank you for that
+wbeaty are you talking about one of those "contactless" induction lamps?
+FoodOnCrack Nope. Tesla's lamps used external metal plates, capacitive-driven with no need for a glass torus. Demo: hold any discharge tube near a Tesla Coil, even one lacking electrodes, and it lights up. The version used in Tesla's laboratory ceilings were phosphor-coated capsule-pipes, with external metal near the ends, driven by HV at KHz. No-cathode, rather than cold-cathode. Last's nearly forever, eliminates the need for billions of dollars of "re-lamping" and hazardous waste stream. Mod your conventional fluorescent tubes by attaching foil electrodes outside.
But Tesla used all his outside funding to build his Colorado lab, when he'd promised investors that he was starting a fluorescent lighting manufacturing plant.
Coulda been like Elon Musk of 1895! Wiped out Edison corp's incandescent lamp sales, become a billionaire, and started any future projects he wanted. Oops.
The one thing I've never understood was the weird faults you see on buses in Edinburgh. When the system starts to fail the tubes will appear to have flowing light and dark areas moving from one end to the other, like a good old rope light sequencing. What's weirder is that when I spot this there's usually three or more tubes doing this in sync.
I always thought it was an effect from a high frequency power supply failing.
Thanks for the description of what appears to be happening in their lob-sided power supply.
Happy 25th December.
+PIXscotland
We have a tube in the basement that does the same. It has darker bands (didn't really measure, but maybe approx. 3-5cm apart) that slowly move in one direction (again, didn't measure, but it's also in the order of 3-5cm per second). The tube does not have an electronic driver and the banding vanishes after 5 minutes or so. If I had to guess I'd say it has got something to do with the gas heating up, expanding and contracting with the drive frequency near the cathodes of the tube. This could lead to some kind of standing (or slightly moving) pressure wave until all of the gas in the tube has heated up uniformly.
+PIXscotland If they are being driven from an electronic supply you may be seeing a standing wave effect called jelly-beaning in the neon industry. There used to be electronic transformers that could be accurately tuned to cause jelly-beaning deliberately.
Absolutely brilliant. Great vid. I have those very same tubes in my camper. Replaced them only 2 weeks ago. Worked fine until this morning: now the tubes are dim, slight purple colouring at the ends. I imagine the ballast units are defective. LED strips here I come...
Thanks BigClive! Awesome video as always. Between this one and the GFCI video, two things I've always wondered about have been explained!
Thanks for explaining this in an easy to digest manner Clive, good stuff to know.
Here I was, stupid little me, thinking I knew how these worked and that it was something easy before going to sleep. now I find myself intrigued... good show Clive (if that's your real name), bloody good show.
Thanks BigCliveDotCom. This brought back memories from 1986-1990 when I designed emergency lighting systems for every tube from 8w T5 to 100w 6 footers. I am not that clever, so we did it by reverse engineering the transformers and pcb's then melded different circuits for our needs and CAD them on a BBC Model B computer. We undercut the Chinese and Germans on many products. I also did mercury lamps, Disco lighting and strobes. Never had many fails though and they went into many new UK buildings! Remember that Jon Kay?
More Sudden Science style videos please! Really enjoyed this informative video. Love your channel. All the best fir the New Year!
Hey Big Clive. I wanted to point out something since you mentioned it.
I just left the semi/truck driving industry, spent a year driving trucks of the likes of Internationals/Freightliners/Kenworths. I am happy to report that the manufacturers are moving towards using LEDs in more of their rigs.
Cheers, mate.
clive, you help me understand all sorts of things. thank you so much. Please keep making videos.
Fantastic! Thank you for some answers to my lurking questions... when I see odd florescent behaviour like darkening or purplish ends... humming and lopsided operation... now I know why. You made the answers fun and easy..
Happy Christmas Big Clive
Wow! What a great video. Lucid explanation of the kind I know I can get only from you, Clive. I'm about to open up a Philips TWS200 emergency lamp and I'm sure your video will come in handy. Thank you.
great video! finally a simplified way to explain cold/warm cathode lighting
I have learned sooo gosh darn much already and only 7 minutes in.
+Applied Science I am coming for you next.
Interesting. I didn't know these were warm cathode tubes. I have used various fluorescent tubes like this for moth trapping since about 2009 and never really looked up how they actually worked. I mostly use the high output t5 12" 15W visible blacklight tubes that produce a visible blue light. Since the end of 2014, I moved to using t5 12" 15W synergetic tubes, and these produce an almost lime green light. These produce two peak wavelengths of light at 368nm and 540nm, which is broader than the blue tubes which peak at 350nm, and as such they work far better at attracting moths than the blue tubes.
I run them on the battery powered car inspection lamps that use the same 8W white tube you have, just switch out the tubes for mine. I power them on 12v 24 amp motorcycle batteries and I can get around 19 hours before the battery needs charged. However, after a long enough use, the plastic tube that protects the florescent tube, does turn a dark dirty yellow colour. Maybe because of the UV light the tubes I use, produces compared to the white tubes that come with the inspection lamp?
That clearly explains the problem I had with battery operated fluorescent tubes in the past as they kept blowing the tubes. The 12V models were even sensitive to being switched on & off. E.g. if switched off and back on within a fraction of a second, it generally caused its electronics to self destruct - a trail of smoke and that burnt electronics smell.
One thing that I learned about learning is that...
The more I learn about stuff, the less advanced I realize the human race actually is. Things are too alike.
I mean, it seems complex, but once you get it down or hear enough about it, you are like, duh. This other thing actually works just like that too.
And mostly, the thing with me about stuff is, I generally have no clue because it never came up in my life. But the second it comes up, I can figure it out. Almost like I knew about it for years already.
Some things do not stick with me though.
Like, is Psychology. I didn't find it important to remember who said what. All I cared about was why it was said. So when it came time to recall the dude, I was like, why?
But yeah, names and flashy words don't stick with me. But, when it is time to learn and develop new things, I am generally the first one with an idea.
I always was wondering how this worked. Thank You!!
Thank you so much, you have a really good way of explaining that makes it so easy to understand.
Thanks a lot for this.
Please make a detailed video on how today's uv ballast works. Like Philips, osram or other brands.
Btw This is the best video on uv light i have seen on TH-cam.
Excellent, had a torch with fluorescent, the switch got knocked to on unnoticed and when the batteries ran down, the tube ends looked burned to hell, now I know why it was worse when it ran down.
Brilliantly clear and informative - well done
I recently went to the store to replace some and was happy to see that LED versions are barely more expensive and easy to get now.
And now I finally know how those old starters work. Thanks!
Very informative! I always wondered about this, thanks for a very educational and detailed explanation. Depending on how this is received by your viewers, I for one wouldn't mind a followup going into the additional subtleties you mentioned at the end.
I was waiting for breaking glass @ 4:40 :D
And, if you want to use a cold cathode driver on a hot cathode tube, you can get away with wiring up in the exact same way as a standard mains driven circuit, but insert a fairly high value (4uf to 8uf) non-polarised electrolytic capacitor in place of the neon 'flash' starter. Now, I don't know how long the tubes would live, but we played with this at my brother's workshop before the electricity was installed (we had a ready supply of 24v "Transis-Star" or maybe "Tran-Star" (I think they were called) "electronic ballast" units.
We already knew, by experimentation (we smashed one!) that some tubes had a disc electrode behind the heater. I think these were the old fashioned "Atlas Lamps" fluorescent tubes, and we postulated that the disc electrode might be better suited to cold cathode applications.
Anyway, we ran several 4 foot (40W) bog standard basic tubes this way to light the workshop from a series/parallel set of tractor batteries, charged by an old Petter engine, driving a 24v alternator taken from the same old ex-RAF crew bus. - once again, I may still have one or two of those Tran-Star (or whatever) electronic ballast units, though they were definitely transistor oscillators with two decently beefy output transistors in each unit. Each unit could be wired to drive 2 x 2ft tubes either in parallel, or in series, or could drive 1 x 4ft tube, and at a pinch, would actually drive a 5ft tube on freshly charged batteries.
Once again, Clive, you are stimulating my brain into thinking outside of the box - thank you.
Well explained.
Subscribed!
Cheers from KCMO, USA.
I remember having one of those battery-operated flourescent lights at one time, it took 4 C or D cells, and never did work really well. At this point I'm not sure what happened to it.
I used to have a couple of 4-foot fixtures hanging over my workbench. These worked fine, but there were times when I noticed a certain "fuzziness" on my scope. Looking into it a bit, I found that the fixtures apparently had electronic ballasts in them which were radiating at around 38 KHz or so, not exactly the same frequency, but pretty close. After a move I have an LED bulb hanging over my bench, and those fixtures are in the garage, where they will probably get put up at some point.
In recent months I have scrapped out a fair amount of gear, including some flatbed scanners and some flatscreens. The scanners had small flourescent tubes in them, and in some cases I also snagged a driver board to run these. I'm not sure what they want for power, but am guessing that 12V is pretty likely. What's done in flatscreens can get pretty interesting. They have inverters of a sort, and I've salvaged some of those transformers to play with. Apparently the logic of the way those work is that if there's any kind of an issue with either the lamps or the inverters, the set will shut things down, rather than letting it be obvious as to where the fault lies. I haven't figured out a way to troubleshoot that yet, and probably won't pursue it much further as the newer stuff is all using LEDs anyway. I do recall seeing a gadget or two on ebay that was supposed to let you test various bits of this stuff, but never pursued it, and at this point probably won't...
you are noiw my favorite british person
thank you for being educated
Absolutely fascinating video! Very well explained too, I certainly learned a lot tonight! =)
I love those preheat fixtures with starters, I actually have one in my basement with a rapid-start fixture, the preheat fluorescent in my basement is a sears fixture
Spot on Clive! Thanks a lot for taking the time to make that video :-)
Wow, thanks for uploading this.
What a knowledge on that topic ... Impressive
Some thing also interesting to note is my experience with the older larger tubes 5' and 4 ' , we had light tables which were very heavy and they stood on a concrete floor, there wer aproximately 30 odd tubes in the tables, I worked on these tables for over 12 years and the tubes were still working fine with very limited darkening of the ends, by comparison the tubes which were on a suspended timber ceiling used to last only a year or two before giving out one way or another. reason for this was obvious VIBRATION, the light table tubes were rock solid with nil disturbance.
We purchased a house in 1964, which has a storeroom with a fair stock of spare fluorescent tubes. Over the years we used them to replace the bulbs in our kitchen, as they failed. These old tubes lasted for many years before they finally failed. Any of the newer tubes generally last less than a year.
Planned obsolescence? Hard to argue against the evidence.
See "The Light Bulb Conspiracy" documentary about planned obsolescence...
Flourescent tube that dies in a year is insane thing. If it was running 24/7 it can run more than 5 years i dont get it
Must be instant start ballast and awful ton of starts?
Very interesting Clive ty once asked an electrician friend about this , but you know what the average electician is like ;-) I got the vague no idea answer, although , to be fair he was an apprentice at the time, but yours is the best explanation I hVE SEEN :-)
I've always wondered why some tubes have a moving pattern in them when lit, (the light is on but not quite as bright as normal but with a snaking pattern that shouldn't be there). Nice one Clive.
+Graham R Dyer This often happens with new tubes randomly throughout an installation, but usually stops after a while. (But not always.) I actually like the squiggling effect. I've never come across a decisive reason for it though, other than "impurities in the tube" which may be residue from the electrodes.
The neon industry tried to recreate the effect deliberately for many years without lasting success. You can do it with short xenon filled tubes and high frequency drivers though.
excellent! I now understand the parts of these fittings - cheers
Thanks! This was genuinely very interesting! :) I have a bunch of those handheld fluorescent lights, bought them on a outlet department in a local hardware store once. They use 2 AA batteries and many of them came with the tubes already considerably darkened at the ends, so it's probably safe to assume they use the bad way of driving the tubes.
any chance of a video on metal halide lights?
Back in the early to mid 1980's, my grandfather used to turn the heat off in his garage, next time he would come in and turn on the lights (USA fluorescent light bulbs) they would only come on dim of if used his cigarettes lighter to heat one or both ends, these were usually, 4 to 8 ft, why did this help, and does this still work to-day on straight tubes and curled household fluorescent light bulbs.
Thank you Dennis
+Dennis Friedman In very low temperatures the mercury will condense out completely and the tube will just glow with the carrier gas. Heating the tube will help get the mercury back into vapour form. You get thermal sleeves for tubes used in refrigerated cabinets.
Enjoyed this a lot. Also, I'd very much appreciate any follow-ups about the same subject (neon signs/CCFLs/etc.)
I build machines that made those lamps and you telling the right story. Good job ashame that they are slowly replaced by led.
***** led is not better
Its a strange color and the electronics heat up and dies after a while
+J IJzer No one even noticed at work when we switched to LED... except the power company who halved our bills.
Fantastic explanation! Thanks!
I really like your channel, but I would love it if you started doing more of these explanatory videos!
Keep up the good work and lets get you 100k subscribers!
Duuuude! Very well explained! Sputtering, rectifying effect, high frequency operation, couldn't think of something missing. OK, maybe resonant operation and stuff like striations... ;)
You Sir, are awesome at explaining this. You should explain other things.
I like the way Clive says "tube"
Fantastic video!
wow sir you'r knowledge is amazing thanks for sharing