Added: 2 years ago
From: kdarrah1234
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  • Wow thats great. My english skills are pretty bad, but i think i understand it :)

    I'm amazed :D

  • @WillstDuNichtWissen great, glad I could help

  • hi, I know this is an old video but I really need to find out how to wire togther RGB leds for a 3x3x3 or 4x4x4 cube can you email me a sketch for this please?

  • @billynightmare I also too would be interested in some hints on how to build a 3x3 RGB led cube with Arduino. I do not want the sketch, I want to learn how to do that (but yeah, the sketch would be great for this purpose)

  • Thanks a lot to this video, I understand how it all works etc but it gets really confusing multiplexing twice! But thanks again, I ordered a couple 8x8 led matrix's just to make it show my name ( T then R then E ...) but it looks a lot harder, I use picaxe as it uses more basic coding ( I am only 15) but I want to use a Max7219CNG but have no idea how to send serial data to the chip from the pic :/ 

  • That is multiplexception! o_0! I would really like to know how you programmed this, very interesting stuff. I just ordered an 8x8 RGB matrix from sparkfun and I'm looking forwards to playing around with it!

  • a BC548 (transistor) will work? Because for the anode it's working, but for the cathode not (for me)..

  • 12 pins? Why dont you use a demultiplexer IC with 3 inputs? 2^3 = 8 You could make this by 3 pins instead of 6.

  • @sonus89 Like: 74HC273 does it.

  • Thanks for the upload! You are the first person who could explain me what is multiplexing! Nice video!

  • so if the pin's are the power source... you also need a 5v battery? :s 

  • would it not be easier to have all the cathodes on a stage connected, and then all the anodes going down, so you con light up a single led without having to have them switch, even though it would have more pins?

  • if you used "emitter follower" biasing for your transistors...then you can eliminate ALL THOSE RESISTORS"!!!!!

    Mark Allemang

    Sault College, Sault ste. Marie, Ontario Canada

  • New to this so forgive me if i sound stupid, but at 6:30 there are 8 transistors that are connected to the cathodes and the pins, and there are 8 transistors that are connected to the anodes and pins, and then the 3rd part of the transistor goes to the corresponding part of the power supply? I am also going to make an led cube, i really wanna make a 4x4x4, but i think ill start with a 3x3x3, anyway what model of arduino do you recommend to use in this? I heard the Uno and its predecessor r good

  • Comment removed

  • I liked your Multiplexing I, II, do you have the source code. I would like the arduino code so I can multiplex my ADXL3xx acceleratometer. Thanks. and do you a LINK for it? I can't find a link.

  • @kdarrah1234

    Sorry I probably sound stupid to you, but I was wondering if you could maybe make a video on the code on the arduino as an example for this multiplexing thing (or maybe pm me for an example). I have spent hours trying to think of a code for that flash on and off thing where it has the illusion of many LEDs turned on at once. I am making a scrolling led sign with my arduino uno, (which has been multiplexed to fit all the pins on my arduino) but I always get screwed up with the c

  • @kdharrah1234 Sorry I probably sound stupid to you, but I was wondering if you could maybe make a video on the code on the arduino as an example for this multiplexing thing (or maybe pm me an example). I have spent hours trying to think of a code for that flash on and off thing where it has the illusion of many LEDs turned on at once. I am making a scrolling led sign with my arduino uno, (which has been multiplexed to fit all the pins on my arduino) but I always get screwed up with the coding p

  • I meant pm me an example sorry :)

  • Sorry I probably sound stupid to you, but I was wondering if you could maybe make a video on the code on the arduino as an example for this multiplexing thing (or maybe pm me for an example). I have spent hours trying to think of a code for that flash on and off thing where it has the illusion of many LEDs turned on at once. I am making a scrolling led sign with my arduino uno, (which has been multiplexed to fit all the pins on my arduino) but I always get screwed up with the coding part. Whene

  • thats not actually multiplexing, if anything its demultiplexing, but reallly (de)multiplexing is coding bindary to unary or vice versa, as far as i know of. maybe this is called multiplexing, too, and more viable than using a chip, aynway with a decoder chip you can get 8 lines from only 3 inputs.

  • Dude, that is some heavy stuff. I am very good with small electronics and am very good with a solder gun. I want to learn how to do LEDs. What is a good book or magazine I can get. Something along the lines for intermediates. Thanks

  • @soonercarports i would check out "practical electronics for inventors" its a pretty decent book

  • sorry maybe stupid question...

    but if you want to pultiplex with the arduino and you want in a 3x3 matrix light up

    2 LED's vor like 2 seconds, you need to put 1 LED on for like 5 microseconds put it of and then the other one for like 5 microseconds... but if you want the 2 led's be on for 2 seconds, how many times you have to write command's for the arduino?

  • you lost me @3:00

  • ok, i'm very new to this. so, forgive me for being dumb by asking some questions:-

    1.what is Pin?

    2.what is ground (is it any piece of metal?)

    3.why are the bases of the transistors connected to Pins?

  • @sudjs96 no problem, the pins are where you actually make the electrical connections to the devices. "they look like little metal pins" the ground is wherever you connect the negative part of the battery or power supply, and the bases "which are pin 2" on the transistors are connected to outputs, or "pins" on the microcontroller, hope that clears things up

  • @kdarrah1234 so a pin is actually where you connect the led to the battery? or ... ? :s

  • @sudjs96 pins are like, well, pins. they are metal pieces on components. also they can be metal pieces in general that connect to the power source/ microcontroller. the ground is just the - electrons. it completes the circuit. so it goes positive, led, negative, for example

  • If you multiplex too heavily the LEDs get very dim because they each are on for such a tiny percentage of the time.

  • @GaryVolts good point, there is definitely a cut off on how many you can have since their OFF times start to get longer

  • @kdarrah1234 So if you'd want more LEDs tho be multiplexed at the same time you could just divide the Cube into two different parts that multiplex individualy but at sync. So basicaly having more then one cube working together to make a larger LED Cube.

  • I'm wondering if you could just use transistors on the cathode side and just directly supply current to the anodes? (through pins), i realize this is less powerful, but it "should" be the same thing, right?

  • wouldnt it be easer and less messy to use an intigrated circuit instead of a bunch of transistors!

  • just wanted to ask, right its late it might be a stupid question, but i have a pic, with 4 outputs, i need 6 outputs to control 9 LEDs and i dont fancy ordering a chip that has alot of outputs ... is there any way to make 9 LEDs work with only 4 outputs? any help would be very greatfull

  • what about the 1 LED that is shared between the row and the column on your 8x8 grid its there just 2 different ways to turn it on?

  • @mmichaud08 not sure if I'm following on you since each LED in an 8x8 grid will need both a column and row to be activated in order to enable the LED.

  • umm... what about power dissipation?

  • @legokidnaruto actually its pretty good if you think about it... only one LED is on at a time, its like having only one LED on all the time!

  • @kdarrah1234 yeah... wel i suck cuz i forgot to mention that i want to make some sort of led screen and it will light up one row of led at a time and the collums will be controlled with tlc5940's so each led will be on but the dimmness will be controlled by the TLC's...... (I guess i fail AGAIN...)

  • @legokidnaruto oh, well good luck anyways!!

  • doesn't the arduino get tired of this??? XD

  • @tootjeey ha! yea, thats a good question, but in "electronics years" that is actually pretty slow... the arduino runs at 16MHz, which basically means it can "do" an instruction every 62 nano seconds!

  • What Arduino do i want to use?

  • @TheIhacklover2 I'd go with the standard... dueme! that's what I got

  • Love the video but having difficulty with the code for the arduino, mainly the syntax on how to write the data for the outputs. I'm slowly learning C, and the examples I see do things many different ways with little explanation. thanks

  • @Carlr54555 thanks!! I'll probably put some of this code on my site soon... kevindarrah,com downloads arduino

  • Thanks this helped me understand the concept a lot better. Great video good explanation.

  • @ipodbomb thanks!! glad it could help

  • It is possible multiplex charlieplexed multiple matrix??

  • @avpc79 absolutely!! check out my binary clock videos

  • Question: It is possible multiplex a charlieplexed matrix???

  • can i use 10 k resistor? or 1k? i want to build a multiplex spectrum analyzer i testing it with 10 k ..is 1k better for this?

  • @Vocoder07 well, 10ks won't hurt anything. The problem is that you might loose brightness, or even worse would be if the transistors don't activate. I would at least test it out

  • @kdarrah1234 jo thanks...and sorry for my bad english...i come from germany :D

  • OMG, I would like to try this some day. Great great vid kdarrah1234

  • @heyzuz23 thanks!! I hope you do try it!

  • Thanks for the tutorial! I could use this to control a LED matrix with only 15 pins. I've always wondered how I control more than 15 LEDS at once!

  • @RCT3tycoon yep, its pretty cool stuff! This opens the door for many new projects

  • Hes gonna need a new marker

  • @Gfdtink haha, I finally bought a dry erase board

  • multiplex makes you lose bright?

  • @bourlotg well, the more you lights you have, the less the brightness... I might make a video explaining this in detail

  • Great video. Can u please make a list of all the things u need to make a LED cube 4x4x4 because I'm planning on making one but I'm not sure what I need.

  • @enrique111112 everything you need is shown in the video: wire, 64LEDs, 16 NPN transistors "2N3904", a crap load of 1k ohm resistors, and an arduino setup... good luck!

  • @kdarrah1234 alright thx ill see how things work out.

  • What're transistors and pins? and how do I connect it to pc and program it?

  • @leonidhaimov Check out some of my other videos, and you might get a grasp on how these things work... I was thinking about making a very beginner's type of tutorial on transistors

  • @kdarrah1234 Yes please.

  • Wow, really good explanation. However, I have 1 question: is the resistor between the right NPN-transistor and +5v also a 1K or is it different?

  • @craze4589 all of the resistors connected to the bases are 1K, you can experiment with different values for the ones connected to 5V, since they are the current limiting resistors. The transistors drop so much voltage, that you can actually go pretty low with the resistance; I just did a project where I went down to 50 ohms, Make sure you gradually make these changes though, you could blow the transistors, LEDs, or worse, the microcontroller

  • @kdarrah1234 Thank's for your explanation. My arduino is still on it's way to me. However my PCB is almost complete. (just need to solder the resistor's and the 6 transistor's in).

  • about the transistors

    can i plug the transistor for the anode to +12v instend of +5v?

    thanks

  • @herctrap

    yep, just make sure you are still using a resistor for the leds

  • @kdarrah1234

    i did it but i dont have 12v between the transistors but 4,6

    why i dont have 12 v?

    all are npn transistors

    in multisim

  • Awesome vid, I always wondered how charlieplexing worked. Never knew it was actually just addressing one at a time.

    Multiplexing is big out in industry, but not typically using LEDs (charlieplexing). Most multiplexing is done with transistors rather than diodes, typically in the form of ICs.

  • @smileman66

    Yep, thanks! It is actually quite simple when you break it down, and really cool when you see it all work.

  • thanks a lot this video has risolved me a lot of problems . it's ok any type of npn transistor?

  • @Tuttipazzixpizzi

    Well, I used 2n3904 transistors. I was only dealing with 5V at about 20mA, but if you were going to control higher power outputs, you might want to get higher rated transistors

  • @kdarrah1234

    so with arduino is ok the 2n3904?

  • @Tuttipazzixpizzi

    Yea, the voltage is fine, but just do a little ohms law on your load, so that your current doesn't exceed the rating.

  • Thanks for tip always been kine in electronics hopefully be going to uni next year and study it

  • @gexsjack what about doing it with just 2 pins, set a 555 to add two counters, horisontal and vertial, then depending on the time iluminate the led required!

  • Thanks, that was a really cool video. Did you have any training to do all this?

  • Thanks a lot. I am in college to be an electrical engineer, but working with microcontrollers has just been a hobby. This is why I am not sure how multiplexing is practiced in industry. This was just an idea I had, and it seems to work very well, my cube has been on constantly for a few months now

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