Looking for bus controlled LED driver

[ovnr]

10m 2.5mm² cable to the dimmer (effectively 20m): voltage drop of 1.3V, at 120W per dimmer @ 24V. Not a problem, and you can tweak the PSU to output a little higher voltage too - most have a trimpot. There's no problem at all. You could go with AWG 22 wire to the panels too (0.3mm²) with acceptable voltage drop (0.4v), saving some money.

I did see some... questionably genuine Meanwell PSUs that may be of interest. Fan-cooled, but will handle 40 tiles each (at least). Only $2.2 per tile.

[Medium]

"questionably genuine" I like that phrase.

The dimmer modules you designed were for 8 tiles each, correct? So I could in theory plop 5 of these into one of the PSUs, and would make sure I limit my total average output over these 40 tiles to 50%. That would be correct? The price is quite nice. How do you find these things? Aliexpress is super confusing for me to navigate. Getting to the relevant sections alone is difficult, let alone spotting suitable parts in the masses. Thanks again!

[ovnr]

Yep, five 8-tile dimmers per PSU. To be honest, you'd probably be fine running the whole setup on two 600W PSUs; for day-to-day use you will probably use less than 50W total. Hell, I'd consider buying a nice 100W PSU, then just having a beefy contactor switch over to the cheapo PSUs when you feel the need to set fire to your eyes.

Also, the nice thing about keeping the PSUs separate is that you can just re-wire the power supply cabinet if you find that you need more sustained power.

Do note that you will need two 2.5mm² wires per dimmer, or a total of 38 wires (oh, and no, you do not need to match the lengths - the dimmers will support compensating for the input voltage). If you did need 10m, that is quite a lot of wire and will cost a fair amount.


Aliexpress: I generally just search, never even tried browsing it...

[kolbep]

Use WS2811 LED Driver Chips,
or WS2812 LED Chips with Built in Drivers
A lot of people use them for the fancy christmas displays

you get them in Strips of Pixels (LED Striplights), individual LED's or in Strings with Pixels

Pair it up with a PC/RPI and a SanDevices E682 DMX to Pixel Controller and have a blast.

This lightshow uses lots of them (Eg in the Arches they just have the 3m or so of the LED strips.
You can individually address each pixels RGB and Brightness. If you use the Vixen software it is even easier to design 'shows'

[arobincaron]

Use WS2811 LED Driver Chips,
or WS2812 LED Chips with Built in Drivers

I read this thread with the intent to suggest use the same.  I've used WS2812 and it's pretty amazing what they are capable of.

WS2812 might be perfect though you don't get to pick the LED/casing and WS2811 would allow doing anything as far as LED.

[ovnr]

WS2812: I've certainly thought about them, but:

A) You need RGBW, not just RGB. There are SK6812-based addressable RGBW strips, but they're substantially more expensive ($10/meter vs $4.5/meter), so even adding in the cost of a separate driver means the RGBW strips are cheaper.

B) I don't quite think you've contemplated the scale of this project. It'd involve 300 meters of LED strip, and 18 000 LEDs. You'd still need drivers for every single piece of WS2812 strip, because daisy-chaining several thousand is not going to work. Also, there is zero gain in using addressable LEDs, as you'd always be setting a whole set of 120 LEDs to the same value anyway.

C) They run on 5V. This means wiring costs would explode (you need 5x as much copper - and the whole mess would reach something on the order of 1100 amps peak), plus there will be way stronger brightness changes across a strip.

D) They only offer 256 levels. That may sound like a lot, but you will lose all control at lower dimming levels, since under normal operation the tiles will only run at 10-15% power.

As for buying WS2811 driver chips: Since these are constant current devices, you can't really use them to drive whole strips. They just don't offer enough current capacity, and you can't easily extend it. And even if you did... well, they're still $0.13/pop, vs the $0.74/pop PIC micros (and you'd need output transistors in either case). Not a massive saving; even if it worked, it'd be on the order of $100.


It's entirely reasonable for a smaller project, but by the end of the day, you'd end up wasting well over $1000 by going for addressable strips.

[Medium]

Yep, five 8-tile dimmers per PSU. To be honest, you'd probably be fine running the whole setup on two 600W PSUs; for day-to-day use you will probably use less than 50W total. Hell, I'd consider buying a nice 100W PSU, then just having a beefy contactor switch over to the cheapo PSUs when you feel the need to set fire to your eyes.

I'm still not convinced that they would be THAT bright, but my tests will show. My scepticism is because I would by far not have a build that is aimed at squeezing every last photon out of the panels into the room, since I'd be missing the light guides and have a generally simpler construction in mind. But that's one of the things I'll defenitely find out.

Wire costs aren't too much of a concern. A friend of mine works for a company that wires large industrial plants, and they usually consider anything <50m at these gauges as "rest". I'll have the chance to get some cables quite cheaply there after they had the right kind of customer. Time is on my side here.
Voltage compensation in the controllers is a mighty fine feature! Cool.

Aliexpress: I generally just search, never even tried browsing it...

I guess it comes in very handy to roughly know what exists and what you want for this. A luxury I'll have to learn. (And currently do!)

Regarding the addressable strips:
I also looked at them in the beginning thinking "oh, handy", but then realized that being able to control every LED is wasted functionality in my case, and also figured that it would mean a LOT more expensive controllers. They are amazing for actual LED screens made from strips, but I am better off with regular "dumb" strips I suppose. (I also need to watch data rates at some point, since I'd rather not have to offload too much work to the controllers, since I'm a lot more comfy programming for PCs.)

I have a weekend at the office, so I sadly won't get too much further with this project. But I thought: Even if the tiles project is a good 2 years into the future, I could benefit from fiddling around with the controllers much earlier to make myself more acquainted with the tech. My current place has terribly expensive lighting (consumption-wise), and I might be able to whip up something small scale to play around with. I'll try to think of an interesting mid-term solution. (Problem is, that it's basically one big 9x4m room, completely under a roof. Close to 5m high in the middle, and I'm afraid of heights enough to loathe ladders even if only 2m high...) But I already have something vague in mind.

[ovnr]

Well, if you did need to run it on a several hundred watts power level, you might find that you didn't need much heating in the room, haha.

As for (PC) programming: What languages do you prefer?


If you do need controllers earlier, I'm sure that can be arranged too.

[ovnr]

So I happened to have some time to kill, and decided to dust off V-Ray.

tl;dr: Side-mounted strips are not going to work very well - at least not better than top-mounted strips. You should get satisfactory results with a 70mm tall panel, but a 100mm tall panel is better. Note that this is all a fair bit of guesstimating, but it should be close enough.

. Note that the noise level is solely dependent on how long I left it cooking, and my patience was distinctly lower with the bad solutions...

Also, this was with fully lit white LEDs and partially lit red LEDs, hence the somewhat displeasing color. It assumes strips with 60 LEDs per meter.

[Medium]

Wow! Thanks a lot! How well does V-Ray emulate actual physically correct rendering? I tried to model something with Cinema 4D and use its Physical Renderer, but there, of course, are no ways to know at what settings I'd have the equivalent of a 500mW LED worth of light, or if my diffusor is smoked glass or just has a frosted surface. With that much uncertainties, I figured that any result from this could only be misleading. I however lack the experience and never actually compared the real thing to a rendering.

I hope I get around to visit the hardware store tomorrow and see what materials I could obtain in small quantities locally. One thing to consider with 100mm thick plates also is, that the materials to make them will get notably more expensive. Especially because 100mm wide profiles are relatively non-standard. I really hope to get somewhat further this weekend. But I'll have to order the strips anyways, so actually building something functional won't happen this soon.

I thought about actually making the panels like I want them for the full project, but drill small holes into the sides and string them onto two steel cables that go across my current room. Would winding the wires to the panels around a steel cable cause trouble?

[ovnr]

Render results: It's not perfect, but it's within reason and matches my expectations. It only simulates surface interactions (because SSS would make it even slower), but on a thin diffuser, they will dominate. Also actual light brightness doesn't matter for the diffusion results.

Construction: I'd honestly consider just making the sides out of 10mm plywood. Also, top-mounted strips will be a bit more labor-intensive as you have to solder wires between the 4-5 strips, as opposed to run one length uninterrupted.

Steel cables and running wires on them: Not a problem.

Strips: These seem to be the cheapest I could find.

[Medium]

Ah okay, I hoped you could model actual physically correct simulations. But I guess that's near impossible anyways, considering that getting a proper impression of light on a screen is never going to work - even on photos.

I'll go to the hardware store today and see what options they have at what prices for construction. Wood tends to be a lot more expensive than expected - at least in my experience. And I will defenitely try the strips you linked, although they're with separate white LEDs. The diffusor is still a rather diffuse topic though. Local stores won't really have anything like it, and small volumes aren't highly available either at reasonable prices. (I didn't want to spend $200+ just for trying out a few materials.) But I haven't searched intensively yet, that'll be done this evening as well.

Taking delivery times into consideration, I should be able to make some prototypes in a month or so. I found connectors for 4-pin strips somewhere, but can't remember how expensive they were though. But these might make connecting the strip pieces very easy.

Another thing that came to mind: Some strips are common annode, some are common cathode. I can't say which way is the more available one. Would it add a lot to the controllers to make them switchable between these modes? (If that's even possible!) Or would that be too much because both types are widely available anyways?

[ovnr]

You can model it, but getting the parameters right is going to be next to impossible anyhow. Giving it a go anyhow. Again, surface effects will dominate on a thin diffuser (most photons won't travel very far laterally in a 1-2mm thick plate after all).

I did look at local wood prices, and ended up at around $4-$5/tile in total. The issue really is the diffuser, which seems to end up at >$10/tile no matter what I do. Total tile cost around $33-$35. If you could magically get some acrylic sheets for cheap, that'd solve it, but plastics are expensive.

LED strips: Didn't your original strips have separate white LEDs too? In any event, if you get it diffused enough that you can't see each strip, you certainly won't be able to see each LED. As for connectors, I've never seen five-pin strip connectors myself; they'd certainly make life easier tho. Also, you will want common anode strips; common cathode will involve an extra set of resistors and transistors per channel bumping the price up a fair bit, and also make it harder to control the switching times. You ideally want somewhat soft switching for EMI reasons.

Making a switchable controller is going to add a substantial amount of money in any event; it's not worth it.


Prototypes: Do you at least have things like a lab PSU, soldering iron, and other normal electronics kit?

[Medium]

Don't waste too much time on simulations. It was pure curiosity on my side.

The wood prices depend a lot on volume. For small scale testing, it'll be quite expensive. For 150+ tiles, not so much. With regard to the diffusors, I may just have to look out for something not purpose-made for light diffusion that still yields decent results. Anything that is made for lighting somehow ends up at least twice as expensive as one would assume based on the materials used. Buying normal ceiling lamps alone is often a quite shocking experience.

The separate white LEDs aren't much of a problem, you just mentioned earlier that combined chips could yield a more even result. But I am still considering being okay with uneven lighting within one tile, and having the edges brighter may even be a somewhat appealing effect after all. I'll have to see the actual thing though. So no, I'm not really going for the optimal fully professional looking solution, but a compromise between cost and looks.

The switchable controllers are off the table then! Especially since you make a very good argument for common annode.

I actually have a well equipped workshop I can use at work. PSU, stand drill, motorized miter saw, soldering iron, thread tapers, multimeter and all sorts of small stuff is available. We have an electrician that builds our switching cabinets (we do industrial automation), but he already admitted to being next to useless when it comes to anything that fits on a PCB. He only deals and has experience with the big boy's stuff.

[ovnr]

Well, for diffusers, if you could get hold of cheap acrylic, a single layer of diffuser film should be enough. Also, I imagine the prices would drop reasonably much if you talk to the manufacturers about ordering 100+ units.

And in general you will end up spending substantially more for prototype quantity stuff.


Combined chips: Again, turns out it's not needed, at least if you have a diffuser that works at all. Also, you will find that they have a somewhat different power level; around 4W/m of white compared to 5.7W/m for the separate WLED/RGBLED strips. And of course, less RGB power (4W vs 2W, respectively). This is because the combined chips only have 60 white emitters per meter, vs 90 for the separate (as each chip contains 3 dies). And 30 colored emitters vs 60, of course.

If that was confusing, here's roughly how it's set up:
Combined: [RGBW]   [RGBW]   [RGBW]   [RGBW]
Split: [RGB]   [WWW]   [RGB]   [WWW]


Also, how do you intend to mount the tiles?

[Medium]

I have ordered the strips and a preliminary RGBW controller to play and test around with so far. Sadly, delivery times for the items is up to 4 weeks. After that I'll first play around with a few options made from cloth, wrapped around using velcro to "mount" it. (Enabling me to wash it from time to time.) I'm not overly convinced that this ends well, but my mom would like to see if her idea has merit. Who am I to deny my creator? (And it may even be a cheap alternative after all!)

More white power (dear Americans, it's not what YOU read in these words!) is very nice. I recently changed the plan for the house again, which would have upped the tile count to 234. Unacceptable. I'd do half of that. But that also means only 2 instead of 4 tiles per square meter. (I may have to use bigger PSUs and limit at more than 50% output. But total light output still is an open point to test for.)

Mounting would be super simple: The tiles would be sized to fit a standard suspended ceiling, like you often see in offices or so. The benefits of such a ceiling are aplenty: Easy to run cables trough it, damaged / dirty tiles are easily replaced, keeps heat in/out better than naked concrete, and of course easy installation of fitting light fixtures. They would just loosely lay on the frame like the normal tiles.

[ovnr]

Mounting: Thank god, I was worried you were going to screw each tile into the ceiling or something.

Tile count: I'd consider letting the row/column closest to the wall be blank - light shining straight down onto a wall isn't terribly attractive in any event. That gets you to around 176 tiles, if it was a square room.


On controllers: Would you like to have final hardware (that is, the 32-channel design I was poking) in hand for prototyping? It's of course going to be substantially more expensive than the final units due to tooling costs and a lack of quantity discounts, but nothing completely shocking.

[Medium]

As for (PC) programming: What languages do you prefer?

I fortgot to answer this, but it'll probably not make much of a difference anyways. I'd either go for C# or Delphi, since I'm most familiar with these and there is a good amount of usable third party stuff out there.

Mounting: Thank god, I was worried you were going to screw each tile into the ceiling or something.

Good lord no! I cherrish a good challenge, but I'm not a masochist

Tile count: I'd consider letting the row/column closest to the wall be blank - light shining straight down onto a wall isn't terribly attractive in any event. That gets you to around 176 tiles, if it was a square room.

That's a very good idea. I'll have to model this out in C4D first to see how much I save by this, since the room wouldn't be square at all. Could be divided into 4 rectangles with the current plans, which will change anyways a lot until the house gets started. I have to wait for the rent of the occupants of the currently existing building there to run out, and since I will do this in cooperation with my parents (owners of the ground), they need to pay off an older loan before they can shoulder their part of the project. (Read: The banks play along.) I hope we can get there in <2 years. I'm quite eager to get this thing started.

As for the controllers: Once I found a design I'd like to use for my current place to play around with, a full 32 channel job would fit nicely. It would also provide a nice "real-world" test phase to iron out whatever issues may come up. (Or rather: It would be good for me to learn with the real thing.) What would you estimate for a prototype?

[ovnr]

C# is nice. Delphi... well.


Controllers: US$ 160 for two full controllers (not including assembly cost); due to minimums and NREs, more is always cheaper. Each additional controller (up to 5; haven't done the math for larger quantities) is around $50. You can also do a cut-down version without full output drivers which would work well for software development (it would have eight onboard RGBW LEDs) for $25/pop, assuming you buy full controllers too. Basically just the boards and the stencil is $50 down the drain before you even begin looking at parts.

The controllers do have some convenience features that add some cost, like dual pluggable power connectors (so you can daisy-chain several off of one PSU more easily), pluggable output connectors, etc. Replacing these with non-pluggable terminal blocks would drop the price around $7-$10 per driver; note that they're not present on the cut-down dev edition. They're nice to have; whether they're worth it is up to you. Spade (Faston) connectors are another option, but are less foolproof - and getting the polarity wrong will end badly.

[Medium]

Delphi as a language is fairly nice, and I find it more pleasing to look at than C-likes. It's just sad what it's developer is doing to it from a tools- quality- and pricing-perspective for the last few years. I'm actually just at the brink of phasing it out in my job after they were bought out yet again a few days ago, but legacy stuff will ensure that I'll get to work with it plenty, still. Porting a codebase that grew for a good 15 years isn't an easy thing though. I'll basically re-rwite everything, including UIs (which are my focus as the guy responsible for process visualization). But there are many subtle bits and pieces where I see quite well that C# (the language itself) was mainly developed by the very same guy that made Pascal great back in the days.

For the controllers: 2 are even better, leaves more options! Also the nice to haves don't sound overly over engineered but rather sensible. Making pure dev boards would be a waste, though. So, $200 for two fully assembled units, and $50 for each that follows? Do I smell a deal? (I can't yet say how many exactly I'm going to need in the end. Depends on what the room looks like then, and what my brightness-tests yield as a result.)

[ovnr]

Well, the reason why I said "... each additional controller (up to 5)..." was because you'd have already paid for the PCBs. Minimum orders and all that shit.

Anyhow, component cost for a 15-board order later on would be $43 per controller; yes, including PCBs. Do note that each controller contains 137 parts, and I'm afraid I wouldn't do the volume assembly for free. That's a discussion for another day (and place) however.

Dev edition: The idea is that you can have one sitting in a drawer, and can push a firmware update to it to check the functionality before pushing it to the whole damn ceiling - without having to have a 24V source and LED strips dangling off of it. If you somehow were to brick the bootloader, it'd save you the effort of taking down every controller and manually re-flashing them.

I would in general strongly suggest keeping a couple spares too, once you get the full install up. Getting new ones manufactured could easily involve substantial lead times.

[Medium]

137!? Sweet baby Jesus! That is a LOT more than I expected it would take. But alas, if it's well engineered, it may as well have a certain complexity to it.
I wouldn't dare to ask for free assembly. That's why I rounded the figure you stated excluding assembly up to 200, but I have to admit that I can't estimate how much work two boards may already be, at all. I hope I didn't insult you there! You make a very good point for a dev board. Mhhh. Well then, I guess I'd like to have 1 dev and 2 full pieces then
I'm not too shabby with a soldering iron, but when it comes to finer pitches on some chips, and at that quatitiy, I'd probably save me a lot of time and potential trouble, if someone who is more apt at it could do it. (I understand that you need to order more than 3 PCBs in a batch, which makes the pre-assembled options very front-loaded cost-wise, especially because the final count isn't yet determined.) We'll figure something out.
For the time being, please let me know what you need for 1 dev + 2 full boards, fully assembled and ready to play around with. (I'd need a brief spec of the protocols for programming and light-data, too, of course. Something short is okay, since I'm not entirely new to the topic of RS485 comms.)