EEVblog #728 - T4 LED Lighting

[EEVblog]

A quick rant on T4 fluorescent tubes, and a small upgrade to replace a T4 tube with a LED strip.
Previous video on LED lighting Dave's back deck:

[coppice]

I believe T4 was specifically designed for non-standard length applications. Mostly decorative things, with interestingly shaped tubes. They only needed to standardise the ends, so people could mass produce standard connectors.

[SeanB]

A T4 that lasted 12 years, and the lamp actually died and not the ballast. You must not use it at all much, they typically only do 2 years before the lamp goes low mercury and glows pink or dim, or the ballast detonates.

[EEVblog]

A T4 that lasted 12 years, and the lamp actually died and not the ballast. You must not use it at all much

Before Sagan came along, hardly used this bathroom at all.

[pickle9000]

Antarctic themed bathroom. Who wants to guess about the closet under the stairs. I wanna see the Marty room.

[tocsa120ls]

Hi Dave, try http://www.linedict.com/ for translating the chinese symbols. (With all these cheap chinese stuff, demo boards with the user manual in engrish, and the component descriptions in these funny simbols, linedict was great help to me)

The first symbol is a 3, and the last one in brackets is the symbol for comfort (maybe wavelength?) The other are unclear even on a 1080p resolution. So maybe 30W warm white?

BTW it looks even cooler so that the individual leds are showing. Countdown till SWMBO says it is too dim

[SeanB]

Not too bad this time. Only noticed it on a few occasions.

That will be the YT recoding, brainfarting on the fast changing data and saying "ah bugger it I will use a larger macroblock till i get an Iframe" to reduce data rate.

[classical]

Does the power supply have any compliance such as UL or VDE?

[EEVblog]

I can only add (repeat) I only see it on recent EEVBLOG videos. Not on any other recent video on over a dozen other channels I subscribe too and have watched in the past week or two. I don't see it on HD EEVBlog videos.
So if it is YT then I can't see the reason it seems to only affect the EEVBlog.

I've changed nothing. Exact same way I'e shot, edited, rendered, transcoded and uploaded my video for a long time now.
Other people have reported it's happening on other channels, so it's almost certainly not me.

[nitro2k01]

That will be the YT recoding, brainfarting on the fast changing data and saying "ah bugger it I will use a larger macroblock till i get an Iframe" to reduce data rate.

Iframe? You mean key frame? If Dave's Handbreak script doesn't specify the use of key frames, that might be something to look into. Personally, I'm still wondering why Dave standardizes on 25/50 FPS and not 30/60 considering that most LCD screens today run on 60 FPS, which should give less temporal aliasing. I could understand it if a video contains mainly footage from a camera that can only output 25 FPS, but otherwise, 
I wonder if this issue could be related to that too. Perhaps the encoder isn't really optimized for 25 FPS, and gets confused and has to compensate by adding/removing a frame every now and then to keep a constant fame rate, and does this badly. Just a thought. This could be thoroughly tested. First by uploading the SAME video export again and seeing if the same glitch occurs at the same places, as a reference to rule out that it isn't completely random. Then uploading a 30 FPS export and see if the glitch occurs there. And all the while of course confirming that the glitch isn't in the uploaded file.

[nitro2k01]

That's a gorgeous brown wire color on the output. I really like the reddish tone in that brown color. And that really really dark blue color is something else... 
Maybe this is not a pure oversight by the manufacturer, and it refers to where you are supposed to connect the negative and positive wires. But, are there any common standards for LED wiring that dictate blue and brown for negative and positive? 

I would have liked some more playing around with these. You should have bought one or a couple more and maybe...
* Compared the light output, voltage output, and power draw over the full specified voltage range.
* Tested the primary/secondary isolation with your isolation tester.
* And of course, a teardown to see exactly how crap it is inside! Could you feel from the outside that it was potted for example? IP67 pass, or IP67 my ass?

[SeanB]

IP67 when enclosed in an appropriate IP67 rated fitting............ Otherwise IP00.

[Sionyn]

did it pass 'the she who has to obeyed' test ?

[EEVblog]

did it pass 'the she who has to obeyed' test ?

Happy wife 

[EEVblog]

Personally, I'm still wondering why Dave standardizes on 25/50 FPS and not 30/60

My main camera is 25/50fps

[Howardlong]

Personally, I'm still wondering why Dave standardizes on 25/50 FPS and not 30/60

My main camera is 25/50fps

It seems it's not unusual for cameras to be locked to 25/50 or 30/60. I recently bought an FZ1000 4K bridge camera and I was a little surprised that it has two models depending on the region it's purchased in, and it appears locked. While these cameras still support localised legacy standard composite SD outputs, this may remain the case for a while. It'll be a compromise between the cost of providing multistandard and the perceived value to the customer of what could be considered an edge case

[Barny]

Why did you have to fix the light at the lab?
Is there a "Don't fiddle at home" agreement?

I'm glad that you got an good WAF at yout work.

[Dr. Frank]

Dave,

Your rant about non standard lengths of these T4 tubes is not correct!

The numeral in T4 , T5, T8,... always denotes the tubes diameter in unity of 1/8 inch, and the length varies for ALL of these different types  - also in a standardized manner - over the wattage.

Physical background: the diameter will determine  the current density, the length determines the overall burn-voltage, and so the wattage.
Therefore, the length should be correlated to wattage in a proportional manner.
 
Therefore you would have had to buy exactly the same diameter AND wattage as replacement as the old one, or you may also use a different diameter, after you had a quick look into the wattage vs. length tables.

Maybe, you were a victim of an incomplete WIKIPEDIA entry in the English version.
The German version has a good overview and description on this subject, just look at the tables here: http://de.wikipedia.org/wiki/Leuchtstofflampe

Translations:
Durchmesser = diameter
Sockel = socket
Länge = length
Leistung = wattage


PS : Anyhow, it is an interesting video, because I also were not aware of that problem; and I also want to replace fluorescent lamps and "energy saving " ones by LEDs in the future.

Frank

[EEVblog]

Why did you have to fix the light at the lab?

a) Ran out of solder, heatshrink, and double sided tape at home, home lab is practically non-existent now.
b) Had to shoot a mailbag with Sagan anyway (addressed to him)
c) SWMBO was busy. Translation: go away and play with Sagan
d) Thought I might as well shoot a quick video about it while I was there.

[woox2k]

"Nice" power supply you got for those LED's. Cable color instructions are all wrong and that CE marking is most likely "China Export." I would also eat my hat if that thing is really IP67 rated.
It would be really nice to see a teardown of that supply!

[EEVblog]

Your rant about non standard lengths of these T4 tubes is not correct!
The numeral in T4 , T5, T8,... always denotes the tubes diameter in unity of 1/8 inch, and the length varies for ALL of these different types  - also in a standardized manner - over the wattage.

Then please explain:
- why no one sells T4 tubes to match the length I had - anywhere online that I could find, even overseas.
- Hardly any local lighting or hardware stores carry practically any T4 tubes spare, and the rare one that did had every size but mine (close though).
- No one makes T4 LED replacement tubes, yet they do for the other sizes that do have standardised lengths.
- Why many sites (inc wikipedia) confirm that there is no standard, and that it basically what I found when I searched.

Perhaps in Germany, but elsewhere there doesn't seem to be any standard.

[TheWelly888]

High efficiency LED power supply? 170V x 0.53A = 90.1W or 265V x 0.13A = 34.45W so power draw could be anywhere from 34.5W to 90.1W - hardly high efficiency when 10W is output to the LEDs!!

[helius]

Iframe? You mean key frame? If Dave's Handbreak script doesn't specify the use of key frames, that might be something to look into.

"Key frames" is a term in animation. The animator draws (or models, whatever) key frames at specific instants and the animation system "tweens" from one to another. (In cel animation the tweening process is done by animators' assistants.) Terms related to "key" are common in production, like key grip, chroma key, etc.

Video codecs use temporal coding to reduce the average data rate, while allowing both detail and fast motion to be preserved. They do this by assigning frames to different types: the frames with the most detail are called the I-frames. I is for "intracoded", meaning they are complete pictures, no temporal data. In between I-frames the codec uses P-frames, which describe movement in terms of distance from the last I-frame, and B-frames, which interpolate movement between I- or P-frames. P is for "predictive" and B is for "bidirectional". I-frames take much more bandwidth than the other types, about 3x each P-frame and 15x each B-frame, so to keep the average data rate low they are spaced far apart.

The encoder needs to decide which frames should be I-coded, based on movement and detail in the scene. Just adding more I-frames won't necessarily remove artifacts, because each I-frame increases the bandwidth requirement. In order to meet the data rate target the encoder would need to increase the compression level (by dropping more DCT coefficients). The trick is to choose the proper frames for I-coding.

[SeanB]

I just watched the video using a non flash or HTML based player, using the H.264 based player in Mplayer. No artefacting visible, so the YT video is fine, and the browser or app based players ( which probably are using a browser based rendering in any case) are the things creating the artefacting. Totem 2.30.2, and GStreamer 0.10.28, yes it is not the most modern, and still no artefacts visible in VLC either.



Geez, 140M for a 11 minute video.....Dave, I think we can lay this one to rest.....

As to T4 being hard to get that is true, as most stores and wholesalers will not stock a lamp that is cheap ( under $5 each) but with a minimum buy of a case of 25, that might sell one a year or less. With small power tubes you get a lot of size variations, and even more colour temperatures and colours, so to keep a case of each will mean a lot of shelf space in use, for something that both is fragile and very slow moving.

If I encounter any T4 or smaller ( or T5 which does eat the ballast and the tube at the same time) I will look at getting LED strip to replace it. If you want more light add extra strips next to each other, you can put 3 strips in the same place as a T5 on the cover, and get about the same light output.  RGB strips are nice there as well, and you can also get 24V RGB strips, which are slightly more efficient and also have a cheap controller available. I am using some old ones on 12V, just had to do some slight bodge wiring to split it into 2 3 LED strings.

[iva]

The first symbol is a 3, and the last one in brackets is the symbol for comfort (maybe wavelength?) The other are unclear even on a 1080p resolution. So maybe 30W warm white?

I'll give a try at the characters in Japanese (most of them match the traditional Chinese ones anyway):
1: 3 - this is easy

2: (game of) go ? - but the character seems a variation of the most common form, so maybe just a name?
http://www.edrdg.org/jmdictdb/cgi-bin/entr.py?svc=jmdict&sid=&q=1270870

3: color
http://www.edrdg.org/jmdictdb/cgi-bin/entr.py?svc=jmdict&sid=&q=1357600

4: white
http://www.edrdg.org/jmdictdb/cgi-bin/entr.py?svc=jmdict&sid=&q=2751410