Step 13: Choose your LEDs

There are many things to consider when choosing LEDs.

You want the LED cube to be equally visible from all sides. Therefore we strongly recommend using diffused LEDs. A clear LED will shoot the majority of it's light out the top of the LED. A diffused LED will be more or less equally bright from all sides. Clear LEDs also create another problem. If your cube is made up of clear LEDs. The LEDs will also partially illuminate the LEDs above them, since most of the light is directed upwards. This creates some unwanted ghosting effects.

We actually ordered diffused LEDs from eBay, but got 1000 clear LEDs instead. Shipping them back to China to receive a replacement would have taken too much time, so we decided to used the clear LEDs instead. It works fine, but the cube is a lot brighter when viewed from the top as opposed to the sides.

The LEDs we ordered from eBay were actually described as "Defused LEDs". Maybe we should have taken the hint ;) Defusing is something you do to a bomb when you want to prevent it from blowing up, hehe.

Larger LEDs gives you a bigger and brighter pixel, but since since the cube is 8 layers deep, you want enough room to see all the way through to the furthest level. We went with 3mm LEDs because we wanted the cube to be as "transparent" as possible. Our recommendation is to use 3mm diffused LEDs.

You can buy very cheap lots of 1000 LEDs on eBay. But keep in mind that the quality of the product may be reflected in it's price. We think that there is less chance of LED malfunction if you buy better quality/more expensive LEDs.

Square LEDs would probably look cool to, but then you need to make a soldering template that can accommodate square LEDs. With 3mm round LEDs, all you need is a 3mm drill bit.

Since the cube relies on multiplexing and persistence of vision to create images, each layer is only turned on for 1/8 of the time. This is called a 1/8 duty cycle. To compensate for this, the LEDs have to be bright enough to produce the wanted brightness level at 1/8 duty cycle.

Leg length. The cube design in this instructable uses the legs of the LEDs themselves as the skeleton for the cube. The leg length of the LEDs must be equal to or greater than the distance you want between each LED.
<p>I want to run code on desktop computer, but i dont know how to create a User Interface ( a simple software) to send a binary buffer to micro controller.Someone can teach me how to do this.</p><p>Thanks so much.</p>
Thanks for doing this Instructabe! I actually did this as my first electronic project, and it worked flawlessly on an Arduino UNO. I really apreciate you took the time to do a guide so extensive and complete.<br>Now, i wanna manage the cube via Serial Comunication on Bluetooth. So i need an Arduino MEGA(the Uno doesnt have any Pins lef). Problem is, the code isnt compatible with the Mega and i cant fully understand how the PORT commands work, so i am unable to make it work on am Arduino MEGA. Can you help doing a compatible code. (I dont need to use Analog pins anymore to control the cube)
I have the code for the mega. Will post this evening.
<p>Hi!<br>Can you please post the complete code (with all animations+serial programming)<br>for Arduino MEGA!?</p>
<p>Hello!,<br>I also have same problem. I also now want to make more awesome animations using serial communication. Have you found some way?<br>Or have you found some way to use UNO itself? Or i have to go for Arduino Mega?</p>
<p>Pls .pls help me i can't understand the wiring can someone pls give me easy board design i am going to control it with a arduino uno or an arduino no (most probably nano) pls i need help .pls tell me a easy board design. </p>
<p><a href="http://www.pyroelectro.com/projects/8x8x8_led_cube/img/8x8x8_schematic.png" rel="nofollow">http://www.pyroelectro.com/projects/8x8x8_led_cube...</a><br><br>See this..this uses Arduino UNO..<br>I would recommend you to read some tutorials first..like CHR, SuperTech-IT, and Pyro Electro..<br>Then get your hands dirty! :) </p>
Just about to start this project as mg first. Any tips would be lovely. Thanks!
<p>Just be very sure about not to short VCC and GND anywhere!<br>And don't forget the capacitors anywhere, altough they seem of less use but infact they improve switching.</p>
<p>hello all of you, I have an idea to replace 16 BJT by ULN2803, it would save up for your area, and it works very tot.Toi did 2 cube leds and it all works fine however, I did not design the RS232 connection on my circuit. and here are some pictures about it:</p>
<p>Hello DongP1, <br>Can you share a more clear schematic how did you used the ULN2803 and explain what changes have you done to the code ?</p><p>Thanks</p>
<p>OK you, I'm very fun when help you. You can use Proteus to open file schematic and PCB, and i did fixed code. all in here:<br>https://drive.google.com/file/d/0BzXbfPpoHKV5eWQxU1VQODZhTTA/view?usp=sharing<br>when you use atmega32 you must set fuse for it. <br></p><p>and when you solder PCB solder you should note carefully and did not miss any legs, as this is the second circuit face, you can also book for someone trained to do it to ensure circuit reliability. And my final non-electric circuits become restricts motherboard area, it absolutely does not affect the led. And can not forget that it is a 5V supply. Wish success. I look forward to seeing your circuit here.</p><p></p><p>Inside the downloaded folder: principle diagram, schematic print, inside a simulated 3d opened by Proteus, the revised code with external hex file, inside the code can edit custom and standard you, use WINAVR (recommended recommended). and images to set the fuse for ATmega32.</p>
<p>Hi!!<br>Do you know hoe to flash the EEPROM of Arduino just like we do in normal non-arduino boards..<br>i.e. we flash .eep file directly into the micro controller.. do you know any similar or equivalant thing in Arduino...?</p>
<p>Hello, </p><p>Now I got it. The idea to use the ULN2803 is to avoid using transistors correct ?<br>What do you mean that I need to set the fuse for the ATMEGA32 ?<br>I will be using arduino board, either Nano or mega. </p><p>Thanks for your reply </p><p>Jose </p>
<p>is this, if you use it you must chip atmega fuse set inside the IC, the fuse is to control a number of functions such as: using the calibrated internal or external crystal, and and some rather different features, please reference IC data sheet. so that it operates according to your desired this function. I use the load circuit to the load burn-e program for my IC, please find out more about it, or you can use the load circuit which you are available. <br>ULN2803 help replace the transistor 16 in the layer. you read this ic data sheet to learn more. I had to diagram inside folders principle schematic. you see that in order to better understand how it works. wish success! : D</p>
<p><iframe allowfullscreen="" frameborder="0" height="400" src="https://www.youtube.com/embed/4gNiDprbUPc" width="600"></iframe></p>
<p>hello everyone, I have an idea to replace 16 BJT layers by ULN2803, it will save your area, and it works very well I did 2 LED cube and all activities well however, I did not design the RS232 connection on my circuit.</p>
<p>How Do i flash the EEPROM of arduino!?<br>i.e. i want to store the fonts in the eeprom of arduino UNO ..how to do?<br>for eg. i could easily flash the .eep file when using normal AVR board or some non arduino board..but how to do the equivalent thing in Arduino UNO!?<br>PLZ Help!</p>
<p>Hey thanks for the instructable! I finally finished mine. Here is a link to the arduino mega2560 code that i used for my cube.</p><p><a href="https://forum.arduino.cc/index.php?topic=371012.0" rel="nofollow">https://forum.arduino.cc/index.php?topic=371012.0</a></p><p>Hope that helps someone!</p>
<p>Perfect explanations, I have learnt soldering and reading circuits with this project, which had been my final project for high school.<br>I used 5mm LEDs (I think I should have bought 3mm LEDs instead because the sight of the LED at the opposite corner is not clear) and an Arduino Nano v3.0 to run the software. <br>The best thing of this guide is that as soon as you understand how the functions of the provided code work you can easily make your own ones (if you know C)</p>
<p>great job!!!</p>
<p>Thanks for your great instructions. The structure worked great and all without a mistake. The biggest problem for me is still the programming.<br> But should also be creating.<br> sorry for my bad english I have it translated into google XD<br> But pictures say more than a thousand words.</p>
<p>what a neat project ;D ,great soldering job ! You are my idol now. You must be a soldering master or monster ;)</p>
<p>thank you very much. It was a very elaborate work.</p><p>when the housing is done I take a picture.</p>
<p>i think u have same code used in site or different one if u have different one can u send to this email aravin_fun@icloud.com</p>
<p>I am done everything its work good but I feel animation is not working some of that </p>
<p>your cube was look nice perfect</p>
can any one please tell me how to use PC software? (pl dont tell me about escape characters, i already understand them). I want to know how does the PC software send data through COM PORT via serial line. I am using USB-TTL converter, but i'm unable to run the PC software as i suppose it was written for UNIX. i'm having trouble with the PC software functions for advance animations. Also, the terminos.h file and related Header files are not present. where should i run the PC software? in Atmel studio 4, or atmel studio 6, where? i'm unable to understand. all you people, please guide this beginner :)<br>thnx.
<p>https://www.youtube.com/watch?v=qO5z9IuCnXY </p>
<p>what a nice job! I spent a whole week on soldering and debugging (what a struggling job! )I finally decide to make a PCB multiplexer board. it works well and make whole device look nice and clean. I still have 9 pcs PCB rest . if anyone needs please send message to me . 20usd/pc .</p>
<p>what size drill bit?</p>
<p>I've made the LED lattice and am starting on the electronics now but have a few questions:</p><p>What values should the pull up resistors be?</p><p>Is 2k2, 1k or 100ohm the best for the transistor base resistor?</p>
<p>Do you have something like a link ready to a cart with all of the materials except the LED's? That would be extremely helpful</p><p>Thanks</p>
Hi I'm getting closer to being done with my cube and I just wanted to say thanks for making this possible. I've had to make things work my way but you've made it possible for me to do it. I will post a pic when I'm done
<p>You can have programs teaching it? !</p><p>Send to peterabbey52013@gmail.com </p>
<p>please give me a code and schematic email phanquoctri89@gmail.com</p>
<p>Hello, I used the exact set up with an Arduino Uno. As soon as I connect the the 5v pin to the board its stops. No more lights on the arduino. Dose this mean I have a short circuit somewhere? How do I trouble shoot for it? Thanks I'm new to this and was really excited about building one. </p>
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<p>please give me a code and schematic email asimsheikh780@gmail.com</p>
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<p>Hello, I understand that the use of two transistor for each layer is due to the current limitation of the transistor. Can those 2 be changed for a more powerfull transistor ?<br>Also,its not possible to use some kind of shift register to control the transistors ?Use 3 ports instead of 8 ports ?</p>
<p>Great work..</p>
Hii....i built my cube but its not glowing properly....
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<p>Hi, I've added your project to the &quot;<strong>A Collection of WAAAY To Many 8X8X8 RGB LED Cubes!</strong>&quot; Collection</p><p>This is the link If you are interested:</p><p><a href="http://www.instructables.com/id/A-Collection-of-WAAAY-To-Many-8X8X8-RGB-LED-Cubes/">http://www.instructables.com/id/A-Collection-of-WA...</a></p>
<p>Hi guys! ? </p><p>first, thanks to chr for that incredible instructable! it has me inspired, a lot. </p><p>i tried to download the files from the project. but i was not successfull.</p><p>any ideas?</p>
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<p>I tried it, but failed to glow all...</p>

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Bio: I like microcontrollers and LEDs :D
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