Instructables
This is a guide for building an Arduino-based LED music visualizer, AKA a totally sweet digital dance room.

There are various guides around instructables about pure circuit visualizers, but those are generally some kind of amplifier to make the lights pulse and change intensity in response to the power conveyed in the audio signal. I wanted something more along the line of multiple strobes responding to different frequencies of music. The end result is the mutant stepchild of this and this and a little of this, but it is totally worthwhile.

The actual audio signal gets read in from the microphone jack on the computer, so it can either accept its own sound fed back or the sound from an iPod / Rock Band / karaoke / whatever you crazy kids can dream up.

Yay new music! Courtesy of DoKashiteru and the Creative Commons, I bring you an uncensored video of the system in action:


 
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Step 1: Parts / Tools

Parts:
LEDs - Obviously. I bought really bright 10mm ones in varying colors in bulk from eBay, but you can find them on Digikey or Mouser. Higher millicandela ratings are better, especially if you want these to illuminate anything and not just be a spot of color. Shop around to find a good deal.

Resistors - One for each LED. Mine required 470 ohms, but make sure you check the ratings on your LEDs so that you get as much light as possible without burning them out.

Solderless breadboad - For all the circuitry.

Arduino - The computer/circuit interface. An awesome little board. Buy it online.

Wire - Lots of solid-core wire. I needed a lot, fast, so I ended up cleaning out my local RadioShack of this stuff, but you should be able to find it a lot cheaper. Having two strands held together like this is extremely useful, as you'll see later.

Computer - Where the actual computation takes place. Yes, this may be slightly overkill to flash a few lights, but as we inevitably end up playing our dance music from a laptop anyway it worked out just fine.

Power supply - The LEDs will likely draw more power than the arduino can provide, so we're going to be powering them externally and switching them with transistors. You should have a bunch of these lying around from old electronics, or you can find them at thrift stores. See the planning page for what voltage / amperage you need.

NPN transistors - We're using these as current amplifiers / switches. A little current drawn from the arduino controls a lot of current drawn from the power supply that runs through the LEDs. Find them online or at RadioShack.

Soldering iron - Pretty self-explanatory.

Speakers / audio splitter / male-male audio cable - Speakers for sound, splitter and cable to feed the signal from the headphone output to the speakers and microphone jack.

Software:
Arduino - Download the arduino software environment from here.

Processing - Processing talks well with arduino, and has some awesome libraries built in. Download it from here. Make sure you have the latest version of the Minim audio processing library from here. You may also need to get the 'arduino' library to get them to communicate - get it from here and stick it in your Processing/libraries folder.

Step 2: Circuit Design

Picture of Circuit Design
An overall view of the circuit we're building. The two strands of the wire are connected to the high and low voltages, and each LED/resistor pair bridges them to light up. The low voltage strand is actually connected to ground through a transistor so that we can control the amount of current that flows (and therefore the brightness of the LEDs).

Step 3: Planning!

The most important step is to plan out what colors you want, and where. The ceilings in my dorm are best described as "waffle-shaped," with square indentations tiling the surface. These made a very natural grid to lay out the colors, but you'll need to come up with your own plan. You can figure on up to 8 or so LEDs to a single control strand, meaning that those 8 will turn on and off simultaneously.

With a layout all drawn up, now we need power calculations. Check the datasheets for your LEDs to figure out the forward voltage and current. Mine have a voltage drop of ~3.5 volts and have a maximum current of 20 milliamps. As I had a 12 volt power supply lying around, we can do a little simple circuit math using Ohm's Law (V=IR): (12 - 3.5) = 0.02 * R --> R = 425 ohms. For simplicity we round that to 470 ohms. Most 5mm LEDs will have voltage drops around 2 volts and current ratings around 15 milliamps, but check so that you don't burn them out. Remember: the light intensity is proportional to the current, so use a bigger resistor to limit the current if they are too bright. Also make sure the power supply can handle all this current - some small ones are only rated to a few hundred milliamps, meaning you can only power 10-20 LEDs in parallel like we are.

Step 4: Prepare LEDs and wire

It's a lot easier to attach the LEDs to the wires if we first solder them together with the resistors. Cut both the negative (shorter) lead of the LED and one side of a resistor about in half, then solder them together. Once this is done, bend the positive lead and the resistor outwards so that the LED sticks up a little. See the picture for a much clearer explanation.

Next, lay out all the wire and make sure you have enough for each strand to reach. Measure out and mark where each LED needs to go. Once again, the explanation for the actual attachment is best given by the picture. Solder the LEDs to the wire, making sure to keep the polarities consistent - all the positive leads to one wire, and all the negative leads to the other. Once you've finished, test the strands BEFORE you put them up - connect the wires to your power supply or a 9 volt battery to make sure all the lights turn on.

Next, put all the wires up! In my case, this involved lots and lots of white gaffer tape and a standing on chairs. Make sure the free ends all come together at one location, where we're going to put the breadboard, arduino, and computer. I also put little origami globes over the LEDs to diffuse the light - just cut small slits radially outward from the hole in the balloon to make four tabs and it will slip on nicely. See the picture on the previous page for the effect. Bonus points if the globes are made from old lecture notes.

Step 5: Build the circuitry

There's really not much more to say. Connect the positive and negative leads from your power supply to the power rails on your breadboard, and connect the arduino ground pin to the same negative rail. See the picture for a good layout system. Test that everything is working by removing the leads from the arduino (shown in blue, black, and red below) and connecting them to the positive power rail. Current will flow through the transistors and allow the LEDs to turn on (if everything is connected properly). Put these back how they should be and connect the arduino to your computer with a usb cable.

To set up the sound system, plug the speakers and the male-male cable into the splitter. Send the other end of the male-male cable into the microphone jack on your computer. Again, this is slightly overkill if you're only going to play sound from your computer (especially if you can figure out how to use jack) but this way the system can flash to Rock Band or karaoke or anything else that can output on a 3.5mm audio jack.

Make sure your microphone is working - plug the splitter into any audio source, then open up a sound recording program to see if you're registering a signal. Oftentimes the microphone can be muted, so if you have problems that's the first place to look.

Step 6: Code code code

Open up the arduino software environment, and upload the StandardFirmata example sketch to the board. The sketch will allow you to control the arduino over a serial interface, meaning arbitrary code on the computer can control the lights we just hooked up.

The code that actually processes the audio signal is (conveniently) a Processing sketch. It is based around the awesome BeatDetect library in the minim library. The BeatDetect class computes the Fourier transform of the audio signal, and keeps track of the mean and variance of each of the coefficients for the last few seconds. If the value in any of the FFT bins exceeds the variance, a beat is detected and the light associated with that frequency will turn on. </technical>. What this means is that each strand of LEDs will correspond to a different frequency of music - one strand will flash to bass beats, another to snare hits, another to high vocal notes, and so forth, for 26 different frequencies.

Download the attached Processing sketch from below, and modify the ledPins array on line 10 to reflect your own setup. The first pin number corresponds to the lowest frequencies. Once that's done, you're finished! Plug the audio splitter into your headphone jack, start the sketch, and start playing some music. If everything works as expected, a waveform visualizer will pop up and the lights will being flashing. Enjoy!

Step 7: Troubleshooting

The main problems you're likely to encounter are getting Processing and the arduino to talk to each other. Make sure you install the arduino software - this will bring with it all the necessary serial libraries. You can find avoid problems with the circuit by testing as you go - test each LED, then each strand, then each transistor set. If all else fails go back to this to diagnose where the problem lies.

Now that I've managed to squash all the bugs from my own setup, I can't think of what they were off the top of my head. Post any problems you have, as I probably ran into them and have since forgotten.
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jweeks31 year ago
I know this is kind of an old instructable but I was hoping I might get some help. Ive got everything installed and the visualizer window pops up, but the led's do nothing. It worked on another computer but doesn't want to run on my laptop. Any ideas?
jelimoore jweeks310 months ago

Well, @jweeks3, is the audio input set correctly on your computer? I ran intto the same problem before.

tlandrum1 year ago
Has anyone tried to do this was a wave shield?
aazahn1 year ago
I dont know if I'm doing something wrong, but I keep getting this error when trying to verify your code.
Instructable:5: error: variable or field 'drawWaveForm' declared void
Instructable:5: error: 'AudioSource' was not declared in this scope
Instructable:2: error: 'import' does not name a type
Instructable:3: error: 'import' does not name a type
Instructable:4: error: 'import' does not name a type
Instructable:5: error: 'import' does not name a type
Instructable:7: error: 'Arduino' does not name a type
Instructable:11: error: expected unqualified-id before '[' token
Instructable:12: error: expected unqualified-id before '[' token
Instructable:23: error: 'Minim' does not name a type
Instructable:24: error: 'AudioInput' does not name a type
Instructable:25: error: 'AudioPlayer' does not name a type
Instructable:26: error: 'BeatDetect' does not name a type
Instructable.pde: In function 'void setup()':
Instructable:46: error: 'P2D' was not declared in this scope
Instructable:46: error: 'size' was not declared in this scope
Instructable:48: error: 'minim' was not declared in this scope
Instructable:48: error: expected type-specifier before 'Minim'
Instructable:48: error: expected `;' before 'Minim'
Instructable:49: error: 'arduino' was not declared in this scope
Instructable:49: error: expected type-specifier before 'Arduino'
Instructable:49: error: expected `;' before 'Arduino'
Instructable:51: error: 'ledPins' was not declared in this scope
Instructable:52: error: 'Arduino' was not declared in this scope
Instructable:52: error: expected unqualified-id before numeric constant
Instructable:55: error: expected type-specifier before 'Minim'
Instructable:55: error: expected `;' before 'Minim'
Instructable:58: error: 'song' was not declared in this scope
Instructable:60: error: 'beat' was not declared in this scope
Instructable:60: error: expected type-specifier before 'BeatDetect'
Instructable:60: error: expected `;' before 'BeatDetect'
Instructable:63: error: 'in' was not declared in this scope
Instructable:63: error: 'Minim' was not declared in this scope
Instructable:64: error: 'beat' was not declared in this scope
Instructable:64: error: expected type-specifier before 'BeatDetect'
Instructable:64: error: expected `;' before 'BeatDetect'
Instructable.pde: In function 'void draw()':
Instructable:71: error: 'beat' was not declared in this scope
Instructable:71: error: 'song' was not declared in this scope
Instructable:72: error: 'AudioSource' was not declared in this scope
Instructable:72: error: 'drawWaveForm' was not declared in this scope
Instructable:74: error: 'beat' was not declared in this scope
Instructable:74: error: 'in' was not declared in this scope
Instructable:75: error: 'AudioSource' was not declared in this scope
Instructable:75: error: 'drawWaveForm' was not declared in this scope
Instructable:79: error: 'ledPins' was not declared in this scope
Instructable:80: error: 'beat' was not declared in this scope
Instructable:81: error: 'arduino' was not declared in this scope
Instructable:81: error: 'Arduino' was not declared in this scope
Instructable:81: error: expected unqualified-id before numeric constant
Instructable:82: error: 'lastFired' was not declared in this scope
Instructable:84: error: 'lastFired' was not declared in this scope
Instructable:85: error: 'arduino' was not declared in this scope
Instructable:85: error: 'Arduino' was not declared in this scope
Instructable:85: error: expected unqualified-id before numeric constant
Instructable.pde: At global scope:
Instructable:96: error: variable or field 'drawWaveForm' declared void
Instructable:96: error: 'AudioSource' was not declared in this scope
jelimoore1 year ago
Ok problem solved
jelimoore1 year ago
Ok so my input source is my internal mic on my Mac. Any help appreciated!
jelimoore1 year ago
Oh, PS I am using this for everything that comes out of my system
jelimoore1 year ago
This is so awesome!!
cahill2 years ago
Awesome! Thank you pablopeillard
cahill2 years ago
Im getting these errors:
Stable Library
=========================================
Native lib Version = RXTX-2.1-7
Java lib Version = RXTX-2.1-7
Exception in thread "AWT-EventQueue-0" java.lang.IllegalAccessError: tried to access class processing.core.PApplet$RegisteredMethods from class cc.arduino.Arduino$SerialProxy
at cc.arduino.Arduino$SerialProxy.(Arduino.java:119)
at cc.arduino.Arduino.(Arduino.java:168)
at cc.arduino.Arduino.(Arduino.java:152)
at sketch_121117a.setup(sketch_121117a.java:73)
at processing.core.PApplet.handleDraw(PApplet.java:2103)
at processing.opengl.PGL$PGLListener.display(PGL.java:2595)
at jogamp.opengl.GLDrawableHelper.displayImpl(GLDrawableHelper.java:189)
at jogamp.opengl.GLDrawableHelper.display(GLDrawableHelper.java:177)
at javax.media.opengl.awt.GLCanvas$DisplayAction.run(GLCanvas.java:928)
at jogamp.opengl.GLDrawableHelper.invokeGLImpl(GLDrawableHelper.java:425)
at jogamp.opengl.GLDrawableHelper.invokeGL(GLDrawableHelper.java:364)
at javax.media.opengl.awt.GLCanvas.maybeDoSingleThreadedWorkaround(GLCanvas.java:827)
at javax.media.opengl.awt.GLCanvas.display(GLCanvas.java:415)
at javax.media.opengl.awt.GLCanvas.paint(GLCanvas.java:515)
at sun.awt.RepaintArea.paintComponent(RepaintArea.java:248)
at sun.awt.RepaintArea.paint(RepaintArea.java:224)
at sun.awt.windows.WComponentPeer.handleEvent(WComponentPeer.java:308)
at java.awt.Component.dispatchEventImpl(Component.java:4729)
at java.awt.Component.dispatchEvent(Component.java:4481)
at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:648)
at java.awt.EventQueue.access$000(EventQueue.java:84)
at java.awt.EventQueue$1.run(EventQueue.java:607)
at java.awt.EventQueue$1.run(EventQueue.java:605)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.AccessControlContext$1.doIntersectionPrivilege(AccessControlContext.java:87)
at java.security.AccessControlContext$1.doIntersectionPrivilege(AccessControlContext.java:98)
at java.awt.EventQueue$2.run(EventQueue.java:621)
at java.awt.EventQueue$2.run(EventQueue.java:619)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.AccessControlContext$1.doIntersectionPrivilege(AccessControlContext.java:87)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:618)
at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:269)
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:184)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:174)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:169)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:161)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:122)
Already called beginDraw().
Exception in thread "Animation Thread" java.lang.RuntimeException: java.lang.IllegalAccessError: processing/core/PApplet$RegisteredMethods
at processing.opengl.PGL.requestDraw(PGL.java:1021)
at processing.opengl.PGraphicsOpenGL.requestDraw(PGraphicsOpenGL.java:1526)
at processing.core.PApplet.run(PApplet.java:2006)
at java.lang.Thread.run(Thread.java:662)
Caused by: java.lang.IllegalAccessError: processing/core/PApplet$RegisteredMethods
at cc.arduino.Arduino$SerialProxy.(Arduino.java:119)
at cc.arduino.Arduino.(Arduino.java:168)
at cc.arduino.Arduino.(Arduino.java:152)
at sketch_121117a.setup(sketch_121117a.java:73)
at processing.core.PApplet.handleDraw(PApplet.java:2103)
at processing.opengl.PGL$PGLListener.display(PGL.java:2595)
at jogamp.opengl.GLDrawableHelper.displayImpl(GLDrawableHelper.java:189)
at jogamp.opengl.GLDrawableHelper.display(GLDrawableHelper.java:177)
at javax.media.opengl.awt.GLCanvas$DisplayAction.run(GLCanvas.java:928)
at jogamp.opengl.GLDrawableHelper.invokeGLImpl(GLDrawableHelper.java:425)
at jogamp.opengl.GLDrawableHelper.invokeGL(GLDrawableHelper.java:364)
at javax.media.opengl.awt.GLCanvas$DisplayOnEventDispatchThreadAction.run(GLCanvas.java:945)
at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:199)
at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:646)
at java.awt.EventQueue.access$000(EventQueue.java:84)
at java.awt.EventQueue$1.run(EventQueue.java:607)
at java.awt.EventQueue$1.run(EventQueue.java:605)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.AccessControlContext$1.doIntersectionPrivilege(AccessControlContext.java:87)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:616)
at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:269)
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:184)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:174)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:169)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:161)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:122)


Does that mean something is wrong with my arduino library?
Any help would be greatly appreciated
https://github.com/pardo-bsso/processing-arduino
Wow! That's one of the coolest things ever made with an Arduino! But I have also found this site which has detailed instructions on how to make a simple Arduino LED music visualizer. Its also pretty cool and dead simple: 

http://gallactronics.blogspot.in/

It can be of great help for amateur Arduino geeks. :P

Spio2 years ago
Hi, great jobs. Could you tell me which are the transistors that you used before the leds?
SecondTwo (author)  Spio2 years ago
Any NPN transistor that can handle the current will work - I think I used 2n2222s, but really anything should work.

If you want to experiment with fading the LEDs or doing any kind of PWM you'll need to use something more heavy-duty - transistors and MOSFETs dissipate a lot of power while switching, and it's easy to burn up little signal-level transistors like the 2n222.
Spio SecondTwo2 years ago
tanks a lot :)
SplotchyInk2 years ago
I was wondering if it was possible if there was a way to eliminate the computer and have the arduino react to a connected microphone. I kind of plan on making something similar but more portable. I dare say,even wearable.
SecondTwo (author)  SplotchyInk2 years ago
Absolutely! As I said somewhere in here (I think), this project is completely overkill. When the summer residents in my dorm trashed the old system I rebuilt the controller with something like http://www.instructables.com/id/Nixie-Tube-Music-Visualizer/ to get rid of the computer and make it a completely analog system.  The basic idea would be to use a set of band-pass filters to isolate specific frequencies from the microphone input, rectify and time-average each of those frequencies to get a somewhat steady voltage, then use that voltage (potentially buffered or amplified) to drive your lights.

Alternatively, if you're good with microcontroller programming, you could set up the FFT to run only on the Arduino (or some other controller).

If you want to go the analog route, having an oscilloscope handy is VERY useful for identifying the pass-frequencies of your filters and figuring out the necessary gain on the amplifiers.

Mas522 years ago
Is it possible you can upload a higher resolution of your set up on to the site.....ive been trying to get this to work for hours but your description along with the images posted are extremely gauge for beginners like myself. I followed every instruction to the T and my result is the LEDs not lighting up nor responding to the music being played. I have the proper transistors, ground setup, pin setup, and external power source positive lead to the outer positive power rail and the negative lead to the negative rail of negative less. Im really lost at this point.
SecondTwo (author)  Mas522 years ago
Unfortunately this setup doesn't exist anymore, so I can't get any better pictures.  Can you identify more specifically where your problem is? Try uploading the basic "blink" sketch to the Arduino and seeing if you can get the LEDs to light that way - if they don't, the problem is in your circuitry, and if they do, the problem is in the Arduino.

Let me know the results and we can continue debugging from there.
aessam13 years ago
really cool
dogbots1593 years ago
Wow this looks amazing! Could anyone point me in the right direction if i wanted to do this of the inside of my pc? any help would be great because i have little experience :)
hpfev3 years ago
nice project! i have one question though. how bright were those leds? like in terms of mcd. thx
Nman1203 years ago
hey this is a great project but I had to go the long way around to get it to work
1. had to make processing libraries folder(this was hard to find a good answer to to fix the lost cc.arduino library)
2.update the java TX/RX file
3.change the com port in your processing file

but all in all its pretty cool
B.F.L.M3 years ago
This Is amazing! It would be a super cool dance floor too. but reinforcing might raise the price smidge.....
After much re-organising i'm just a couple squares away from finishing my own version of this :) Great instructable and explained well enough for a beginner to figure out. I recommend using music with a very strong beat such as Pendulum, Skrillex or Benny Bennasi, looks great. If anyone has any questions feel free to message me (odds are I had the same problem at one point or another :/ )
I've got everything connected, power is going to the LEDs, but I cannot get them to respond to the music. I've uploaded the standardfirmata to my arduino and your processing sketch and changed the pin values to my own pin values. Help please? I have no idea what could be wrong
tvane12253 years ago
just to be sure... in order to use this? i would need to have the computer running at the same time? is there a way i could make one without having to use my laptop?
xtm493 years ago
I got it up and running, but the lights will flash randomly when no audio is being played. when music dose play the visualizer shows the audio wave form but the lights still just blink randomly. do you know what the problem might be?
SecondTwo (author)  xtm493 years ago
For a start, try upping the "tol" value - beatDetect doesn't have any kind of thresholding, so it still reports beats even when the only signal is random noise on the line. I put in "tol" to ensure there's a minium signal strength for the lights to fire.
Definitely one of the coolest ibles I've seen thus far!

How would you set the frequency for each specific LED? I want to build something like this mainly to learn a bit about arduino and electronics in general but with more of an equalizer feel. Saying that is there anyway to have LED's respond to volume as well. For example if they were in a stack the bottom one would almost always be on and the top would only light when the music is clipping?
Sorry i just read the comment about different pins responding to different frequencies (0 is the lowest, 25 the highest yeah?). Still curious about volume or if some LED's can be made more sensitive
SecondTwo (author)  joshua.bitossi3 years ago
Hey! I think out of the box the Minim libraries don't give you access to specific frequencies or input levels; that is, I don't think you can add a few lines of code within my sketch to get a volume level or define frequencies.

However, you can go digging around in the Minim library files to figure out exactly what they're doing. I've moved on to a new laptop since writing the Instructable and don't have the library handy, but I do remember finding the declaration of 26 FFT bins and where the variance was calculated. It's possible that there are just undocumented commands to read the bin levels, or it should be easy enough to write your own.

Essentially: it's all in the library code! Once you're able to read the volume level, the display gets a bit trickier - you're essentially talking about a 2-dimensional LED display, which can require a lot of output pins. There are tons of instructables floating around about controlling displays (like http://www.instructables.com/id/LED-matrix-using-shift-registers/) so I'd say look around, mess around, and see what you can come up with.
cereeal3 years ago
I know there hasn't been any comments in here for a long while, but I was wondering if there was anyway I could configure this to work with a common anode LED. As of right now my lights are inversed with this program; that is, when there's no sound all LEDs are on.
Thanks.
SecondTwo (author)  cereeal3 years ago
Hey! Sorry I've taken so long to get back to you - grad school has sort of kept me busy. I'm not sure I understand the problem - if you have a bank of LEDs with a common anode (the side where current flows in), those should work as is in the circuit.

If you have a common cathode LED bank, you should be able to substitute PNP transistors and rearrange the circuit - connect the transistors between +5V and the LEDs, with the common cathode connected to ground. You may run in to trouble if you try to use +9 or +12 volts - I haven't used PNP transistors in a while but I think you can run into problems if your emitter voltage is much higher than your control signal. Then again, I may be getting confused with MOSFETs, so you may as well try.

Let me know if this helped (or if you've given up in the month I took to reply).
ginkin995 years ago
Ok, so its been quite a trip, but im almost done putting this all together, haha. And im very impressed so far. Sadly, i just wired my breadboard like the picture shows, and using a test script i found that the transistor is doing the opposite of what i want. When the LED is supposed to be off, it turns on, and vice versa. Any idea why that is?
It is probably way too late for this, but if the transistor is doing the opposite of what you are desiring (which would be the case for a PNP), you could plug in the output to the other side of the transistor (in the picture above move it from the left side to the right side of the transistor). The transistors are set up in a leader-follower stage [the output is on the emitter side (left side)], for a PNP the collector and the emitter are switched. This means that you could just move the output wire over.

SecondTwo (author)  ginkin995 years ago
I believe you may have gotten PNP transistors instead of NPN ones, but the wisdom of the crowd should definitely check me on that one.
Ugh, yep youre right. Looks like im taking another trip to radio shack, haha. Thanks :)
DanNixon4 years ago
I always seem to get errors saying I am missing packages, I actually think this is a problem with me being able to download .zip archives, since I get the same thing when downloading the libraries from the Arduino website for the Mega (library folder empty) but does anyone else need to add the Arduino library before they can run this?
xDGx4 years ago
when the processing sketch is running without arduino it works pretty fast, when arduino is up and running there's a delay on the equalizer and on the leds. is there a way to improve this ? any code optimization or hardware (external dedicated soundcard) ? This is what I'm getting: http://www.flickr.com/photos/xdgx/4877732548/ Thanks!
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