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Topic: 4x4x4 RGB Cube schematic (Read 3923 times) previous topic - next topic

markvr

Hi,

I'm a bit new to all this, but I'm considering building a 4x4x4 RGB cube, following the excellent instructable at http://www.instructables.com/id/4x4x4-RGB-LED-Cube.

I think I follow it all, but one thing I'm not sure about it, in the parts list there are
1x 1000uf 10v capacitor
1x 0.1 uf ceramic capacitor
2x 22pf capacitors

They are in photos but not the schematic.  Does anyone know where these might go?!  There is a schematic at step 16  (http://dl.dropbox.com/u/30407514/published/emihackr97/instructables/RGB%20LED%20cube%204x4x4/RGB%20LED%20Cube%20schematic%201.png)

There are quite a few guides out on the net about building these cubes, but they all focus on the mechanics of building the cube.  It's the electronics I'm not sure about!  I can't find any guides that explain the electronics in detail, rather than just dropping a schematic in and leaving deciphering it as an exercise to the reader!  Does anyone know of any guides that explain the electronics in detail?!

Starting to think that RGB might be a bit complex, maybe best to stick to single colour for my first cube, but that would be boring!

thankyou :)

kd7eir

Those are for the standalone Arduino that is controlling the cube.  Instructions for the standalone Arduino start at step 16, then follow the diagram and instructions in step 17 to place the crystal and it's capacitors.

The schematic references using a pre-built Arduino, but the parts list and instructions use a standalone Arduino, so I can understand the confusion.

markvr

ah brilliant thankyou!  I'd initially be using a prebuilt uno, so won't need the caps. 

Hippynerd

I think that I have looked over this instructable before, i liked the way that he build the cube.

It looks like he's using the TLC 5940, and I dont see any decoupling caps in the BOM. I cant say for certain that every time absolutly... and there is precious little documentation, but the rumor going around is that you should use a 47uf cap on each chip.

The cube I am building is unfinished, im still working on the sourcing side of the design using mosfets, but my cube is very similar to that cube, only its running on a nano, rather than stand alone.

I have a website that I am developing (too slowly, but some days I make progress...) and I will eventually have four different designs that run 4x4x4 RGB LED cubes.
https://sites.google.com/site/rgbledcubes/

There will be:
Charlieplexed Cube (done and documented)
Constant Current Cube (using the TLC5940 chip)
Shift Register Cube (currently under re-design)
Cascaded Transistor Cube (getting closer to working)

This is my list of the more common ways of solving the same problem, but it turns out that there are many ways to control LEDs

Cube building is rather difficult, it might be best to start with a small 3x3x3 single color cube, so that you can figure out what is easy/hard for you to do, so you can practice in advance of the final assembly.

There are many ways to build the cube, and many ways to build the control circuitry. I do not know the best way, but I have tried several approaches, and I hope to have a better understanding once I have all 4 cubes running.

I've included support documentation, like good soldering techniques, how to prep parts to make soldering easier/better, LED details and info, ...
The site is all about making it easier to build cubes, The only thing I dont have is specific parts lists/data or any for sale, but maybe in the future.

Keep in mind that a 4x4x4 RGB LED cube is 192 LEDs, which is kind a lot, and not as simple undertaking, its probably not the best first project as it may discourage you with a lot of difficulty. Try not to get too frustrated.
https://sites.google.com/site/rgbledcubes

markvr

Thanks hippynerd,

When you say:
Quote
It looks like he's using the TLC5940, and I dont see any decoupling caps in the BOM. I cant say for certain that every time absolutly... and there is precious little documentation, but the rumor going around is that you should use a 47uf cap on each chip.


Why is that, where would the caps go, and how do you know what size caps to use in these things?

Your site sounds like it will be very useful! As a suggestion, could you explain the circuits as well as how to build the cubes?  I lot of times peoples guides (in general, not just for cubes) give a circuit with no explanation.  For a beginner that is difficult, because when you build something, and it invariably doesn't work, without an understanding of why each component is there, you have no idea where to start looking!

I think I'll start with a simpler cube and work up.

Hippynerd

http://arduino.cc/forum/index.php/topic,134953.0.html

Above is a fairly recent thread about decoupling caps on the TLC 5940.

The decoupling cap is like a electron resevoir, if you try to light up all the LEDs at one time, the chip may need more electricity than is available, and what the cap does is help keep enough electricity to fully light up all those LEDs. Decoupling caps always go closest to the + pin on the chip.

Mike says they should be 47uf. The datasheet and the TLC5940 tutorials do not include any information about decoupling caps (none that I have found, and I looked.)

I have a lot of work to document the LED cubes, and I wont be able to do all that until I have them all working. Right now I have one working, and mostly documented (not the software part, but the building, and a little about the software and testing)

I have decided on 4 different cubes that operate in 4 different ways. The TLC5940 way is the constant current way, it controls the current to the LEDs, uses very few parts (relative to other cubes). My guess is that its probably going to turn out the nicest, but I dont really know, which is why im building 4 different cubes.
https://sites.google.com/site/rgbledcubes

tomriddl3

hey sorry for bringing this post back :-P quick question..   i order the wrong type of LED's (common cathode) .. and i soldered as specified in this instructable http://www.instructables.com/id/4x4x4-RGB-LED-Cube/  ... how hard and what can i do to convert this from a common anode to a common cathode cube???  any help would be greatly appreciated .. even if anybody can just point me in the right direction.. thanks!

CrossRoads

So you have the cathodes connected together to make the layers, and the individual anodes connected in columns?
Then you will need shift registers like cd74AC164 to drive the anodes high (4x4x3/8 = 6 parts) and NPN or N-channel MOSFETs to pull the layers low one at a time.
There are no good high side PWM control chips that I am aware of, they all want to sink current.
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

Hippynerd


hey sorry for bringing this post back :-P quick question..   i order the wrong type of LED's (common cathode) .. and i soldered as specified in this instructable http://www.instructables.com/id/4x4x4-RGB-LED-Cube/  ... how hard and what can i do to convert this from a common anode to a common cathode cube???  any help would be greatly appreciated .. even if anybody can just point me in the right direction.. thanks!


If you want to use the TLC5940, you will need to use common anode LEDs. If you want to use common cathode LEDs, then you will probably want to either use shift registers and a whole lot of resistors, or charlieplex the LEDs. Another option is transistors. I have a cube that uses 20 npn transistors, and 20 resistors, and 64 common cathode RGB LEDs.

I have an unfinished website linked below with the details.

https://sites.google.com/site/rgbledcubes

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