Solution for single color tubular LED Display - Page 1
Forum section: electronics / projects

author: PeterFW
author_rank: Frequent Contributor
timestamp: February 04, 2016, 03:07:38 am
content: Hello Everybody!A while back i grew tired of not having a lamp on my nightstand.From there things spiraled out of control and i decidet to build a lamp that is really bright, has a warm white light and can run animations.It is one of these "because i can" sort of things, do not ask me for a proper reason, i do not have oneThe first prototype has been build, it works, i am fairly happy with it, but as allways,the first version leaves things to be desired.How would you design such a thing?See the attachments for a bigger version and the one i currently have sitting on my desk.The main problem is a source of not that expensive and warm white LEDs, i use PLCC2 LEDs soldered on the side and WS2803 LED drivers from World Semi to stay low on the cost.It is horribly inefficient and needs active cooling when running on full power (40W) but looks so damn pretty and gets really bright as i wished.I would prefer at this point to use 5mm LEDs and make it wider, but the LEDs are really hard to come by at a price of <10 Cents.The WS2812 single LED adressable strips you get out of Shenzen would be the simplest solution but they do not produce a nice white light and are not that bright.Edit: Here is a short Video:Greetings,Peter

author: sleemanj
author_rank: Super Contributor
timestamp: February 04, 2016, 03:53:18 am
content: Plenty of warm white 5mm led on Aliexpress for cheap.

author: pmbrunelle
author_rank: Regular Contributor
timestamp: February 04, 2016, 03:58:10 am
content: Yes, this is out of controlI think the assembly of the first one sucks... mostly because of too many threaded standoffs. I would use continuous steel threaded rods, with unthreaded conductive standoffs. Put one nut on each end (total of 8 nuts) of the threaded rod, and then one spring under each nut (total of 4 springs) to maintain constant clamping force.The difficulty is that the current will need to go from the bottom pad to the top pad in each PCB, so lots of vias would be needed.I prefer the version with the rectangular PCBs. You could use card-edge connectors going to a circular backplane at the bottom. The assembly of this would be easy, and it would allow for many electrical connections, so it would not be hard to address the LEDs.Service of a broken rectangular PCB could be easily performed. Probably voltage drops with this design would not be a concern.

author: PeterFW
author_rank: Frequent Contributor
timestamp: February 04, 2016, 06:24:17 am
content: Quote from: sleemanj on February 04, 2016, 03:53:18 amMhm, yes. I know that, they are ~1 Cent a piece or below that.Sadly the quality is about what you expect for that price.Quote from: pmbrunelle on February 04, 2016, 03:58:10 amYes it is, been twiddeling with the code, seems like i can spare myself a lot of work and write a library for the display that uses a allready available graphics library.That will make it nicely scaleable and easy to use.QuoteI thought about something like that, the assembly process was still fairly easy, the threading of the spacers took not too much time.Still a pain in the arse though, yes.Mainly i uses threadet rod and threadet spacers because it was the only solution that was cheap and available without waiting 6 weeks for the mail from china to arrive.QuoteThe rectangular design has a major problem, not that much room for anny connector between the PCBs when i stay within the preferred LED spacing.So it would involve a plate, a few rods and a bunch of wires to put everything together.If i would solder the PCBs straight together i would never be able to service the thing if something fails.But... it should have superior cooling performance, the LED oriented horizontally should make for some not too bad heat sinking and convection.