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Thoughts on easier ways to construct an LED "cube"

I ran across this 4x4x4 LED cube today:

and reminded me that Christmas is coming; something like this would make a really nice present for one of my nieces or nephews. ( My daughter isn't as impressed with 'blinkenlights' stuff. ). Oh, and for _next_ year, not this one.

This is not the first such "LED cube" I've seen, but it reminded me that all the "cubes" I've seen so far look like they would require a lot of time and patience to construct. Since "time" these days always seems short, and, as best I can recall, I left my "patience" in a checkout line some years back, I started wondering about how one might construct one of these, perhaps even a 5x5x5 or a 6x6x6, _without_ having to bend a lot of wires and then re-wire the LEDs I managed to link up backwards. ( There always seems to be one or two ).

The best approach I could come up with was an adaptation of something I assembled as an SMT LED display a year or so back: a row of header pins cemented to the edge of a small (1.5"x1.5"?) square of transparent acrylic(?) and strips of hand-thinned copper foil tape

1/16" wide ( plus or minus 60% ) running off the pins, with breaks in the strips where I then tack-soldered the LEDs (Mouser 604-APTL3216CGCK - 570nm, 120mcd@20mA). It was ugly, but it worked.

There are a few drawbacks to this approach. First, I'd want LEDs with a wider viewing angle (these are only 70deg) or some sort of diffuser. Perhaps a second layer of acrylic-or-whatever with scour-frosted "dimples" laid on top of them?

Second, I'd want to use thinner copper foil, since it's opaque and would obscure the LEDs below it. I'd need to check the current capacity of bare copper, but it might be easier to glue the LEDs down, verify their polarity and fix as needed, then lay a cross-grid of thin copper wires across the LEDs and solder those to the LEDs. It's still a lot of soldering, but it feels like it would be easier to work on a bit at a time than a 3D "wire skelton" arrangement like the ones I've seen for other LED cubes.

Now, there's still probably some sort of "useful" upper limit on such displays -- unless I could find some way to automate the place-and- wire steps -- but even with hand-soldering the 216 LEDs required by a

6x6x6 cube isn't out of the questions as long a I could do a few at a time and then put the assembly away without losing track of what had been done and what was yet to be done.

And even with my fumble-fingers skills, soldering (say) 125 SMT LEDs on five separate boards feels like it would be easier to do than building a 5x5x5 cube of supported-by-their-leads LEDs.

The ideal might be 360deg-viewing LEDs on thin, clear acrylic wired with transparent conductors, but I'm not sure if I can achieve that. This year, anyway.

Hm. It might just be simpler to build a POV display "cylinder":

1) Attach two off-the-shelf 8x8 LED panels back-to-back, 2) Mount an edge of that assembly on a motor shaft, and 3) Come up with a _lot_ of teeny slip rings.

Then again... 2x6x6 slip rings, assuming row-and-column addressing? Maybe not so simple.

I did find some other efforts along the same lines:

This suggests a way of laying non-transparent copper onto glass:

Oh, and the company that sells this:

is working on an 8x8x8 cube.

Well, this is a GedankenExperiment(*) for now, but perhaps next year? I can always hope.

(*) German for "They cut our research budget again."

Frank McKenney

--
  I have never understood why it is "greed" to want to keep the money 
  you have earned, but it is not greed to want take someone else's 
  money.          -- Thomas Sowell
Reply to
Frnak McKenney
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Small "stuffed reindeer" with a battery & blinker sewn in it's belly with an LED nose? It should keep running until NEXT year...

I've looked at this -- but, from a different attitude. I.e., instead of treating the interconnect/supporting wires as "undesireable elements", incorporate them into the "presentation".

I've been trying to figure out how to get "lamps" inside ping-pong balls ("sphere of light") and intersupport these balls with chrome "rods" (which, of course, would be hollow tubes for wiring). So, the lattice

*adds* to the presentation instead of detracting.

You really only need power and ground -- let the brains "fly" with the display (sensing a stationary "index" reference).

(If you really wanted to be insane, you could put a coil on the flying panel and induce an electric current as it is spun around its base -- exercise left for folks with far too much time on their hands!)

Reply to
Don Y

On Fri, 29 Nov 2013 14:33:28 -0700, Don Y Gave us:

Take apart a bicycle rear flasher assembly. Most have several flash patterns, and you only need to replace some of the red LEDs with other colors, or parallel off of them, add drivers and more LEDs, etc.

Reply to
DecadentLinuxUserNumeroUno

The appeal/hack isn't that the nose flashes. Rather, that you *don't* replace the battery yet get a year or more of flashing out of it! Until the NEXT holiday season rolls along...

Reply to
Don Y

On Fri, 29 Nov 2013 16:31:21 -0700, Don Y Gave us:

Sorry, but each flash event does have a specific energy requisite and the circuit has overhead to create the firing pulses. Were you to include a properly sized battery pack (the literal type), you could likely get to a year of service, but there would be limits on the number of elements and the diversity in which they are fired. The 4" x 4" x 4" cube is out for a year of service unless you are only trying to fire a set of four elements. If you want a bunch of them to cycle, you need to do math on driven element counts and pulse counts and consumption rates generated by a given design goal. Poof! There it is...

Longevity? Supercaps, and solar daylight hour charging.

Put wifi capable PCs in each and have them all sequence via program. They have those down to a 2 inch cube so...

Reply to
DecadentLinuxUserNumeroUno

Yes. And the "overhead" can be virtually zero!

E.g., late 70's you could get several months "typ" from a D cell using a 3909. If you go with discretes, you can get almost an order of magnitude better -- esp with modern HE LEDs! So, a year or more from even an AA cell is easily achievable.

I said "an LED nose". One "element". And, all it does is blink at a fixed rate.

Frank was musing about "a really nice present for one of my nieces or nephews". Kids (esp young girls) like plushies. And, if *their* plushie is different from the store-bought ones, then all the better!

An LED illuminated 24/7 is boring after the first few minutes. One that

*flashes* -- esp with a slow rep rate -- commands attention as the child has to stay focused on it to *catch* the flash when it comes along.

After a year of this, it's only appeal lies in it's continued flashing when the *next* addition to the menagerie appears (NEXT holiday season).

And, when the "battery" finally *does* die, it's still a plushie -- for as long as the child remains interested in them.

Plushies with solar cells on their heads look wonky. Just let the "battery" die a natural death.

SWMBO used to get a little "costumed Snoopy" each year from work. They would have been good candidates for this surgery. Bury a coil in i=each butt and charge them inductively (at a 2mA rate)

Reply to
Don Y

On Fri, 29 Nov 2013 21:09:54 -0700, Don Y Gave us:

Then what was the 4" cube form factor about? And where is the nose on that?

So anyway... sure... a single led. no problem.

I thought you wanted a 1960s style "color organ" thingy.

Reply to
DecadentLinuxUserNumeroUno

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