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1  Using Arduino / LEDs and Multiplexing / Re: RGB LED lighting fixtures on: September 28, 2011, 01:54:15 pm
Sounds like a cool project - always fun to see how people put these kinds of things together smiley Make sure to post some pictures
2  Using Arduino / Project Guidance / Re: University Project on: September 26, 2011, 11:18:52 am
Yea this is feasible. Posts are correct, the signal processing part is probably the least "documented", and will require some work on your part to understand in terms of literature, etc. The rest is hardware interface and the resources do exist. This is your senior project, so you need to put in the work.

However, complexity wise the Arduino can handle a compact ECG algorithm. The sampling rate for ECG is not that high (the frequencies are fairly low), so you can definitely handle that. You're probably looking at some type of simple time-domain detection (i.e. correlation based on a known feature, or multiple features associated with a heart attack), or time-frequency analysis, requiring FFTs (trickier due to fixed point on the Arudino) perhaps.. or you can look into multi-band filtering if the features are known. Good luck, and hopefully you learn a bunch of cool stuff!
3  Using Arduino / Project Guidance / Re: Interfacing "Mindset" with arduino on: September 26, 2011, 11:10:43 am
I have one of these; put up a short review of the hardware itself on my blog here http://mdbreview.blogspot.com/2011/09/neurosky-mindwave.html. It's definitely possible to interface it. Bare in mind the signals you get from this thing aren't super precise, but it's a lot of fun to play with! Let me know if you have any questions, and I will try to help. Good luck!
4  Community / Exhibition / Gallery / Re: Google Analytics in a Nutella jar on: September 26, 2011, 10:21:18 am
That's a really neat project! I think a lot of people would find this both novel and interesting. Any non-techies would look at this and say "what the heck is that?" And you can be all like, isn't it obvious, its my google analytics. And they'd probably be like "why is it in that jar", and you'd be like where else would I put it?
5  Using Arduino / LEDs and Multiplexing / Inspired LED Strip Lighting on: September 25, 2011, 06:39:18 pm
Just got these guys, they're pretty cool, looking forward to using them. Really satisfied with the purchase (got them over at Mouser); included a short video below. Check out the full review over at my blog: http://mdbreview.blogspot.com/2011/09/led-strip-lighting-review.html

6  Community / Exhibition / Gallery / Re: NeuroSky MindWave Brain to Machine Interface Headgear on: September 25, 2011, 05:59:25 pm
Hey that's pretty cool! Thanks for sharing smiley
7  Community / Exhibition / Gallery / Re: NeuroSky MindWave Brain to Machine Interface Headgear on: September 25, 2011, 04:15:35 pm
I have not connected it yet, but I understand that it's fairly straightforward (they have documentation on the manufacturer's website). So far I've been focusing on using their API to grab the raw signal values, and import them into MATLAB where it's simply to try different filtering techniques and visualizations of the data.
8  Community / Exhibition / Gallery / NeuroSky MindWave Brain to Machine Interface Headgear on: September 25, 2011, 08:48:47 am
Hi everyone, I recently got a chance to check out the NeuroSky MindWave headgear; it's an inexpensive, single dry electrode EEG system for under $100. If you have any questions I'd be happy to answer them. You can check the posting on my blog here http://mdbreview.blogspot.com/2011/09/neurosky-mindwave.html.

If you have a project you are interested in having reviewed and shared, please feel free to contact me at majordecibelreview@gmail.com
9  Community / Exhibition / Gallery / Re: LED Music Visualizer on: September 25, 2011, 12:16:10 am
Hi everyone, first of all thank you so much for all the views and feedback I've received over the past few months while this project has been up! It was really cool. I wish I had provided more info in greater detail, as I know some people have expressed an interest in just that. While I haven't gotten around to flushing out all of the details on the LED Music Visualizer project just yet (hopefully I will), I just wanted to let you know that I'm piloting a new blog. I'm hoping to run it as a third party "project review" site with links to other news, etc. You can check it out mdbreview.blogspot.com. My contact email is listed on the blog, so if you are interested in getting some exposure for your blog, website, or videos related to your projects, feel free to drop me an email and I will see what I can do. Cheers!
10  Community / Exhibition / Gallery / Re: LED Music Visualizer on: July 12, 2011, 07:28:02 pm
Finished a stand alone PCB and mounted all hardware; USB powered, very simple and low cost. I have since redone this with three high brightness CREE LEDs which look great vs. the single RGB LED. Very bright!



Haven't updated the blog in a while, but plan am now planning to release full code at some point soonish, and maybe some more details at my "blog" (haven't updated in a while).

Thanks!

http://majordecibel.blogspot.com/
11  Using Arduino / Audio / Re: Audio Input on: February 21, 2011, 08:08:16 pm
First I think that all of the answers above hold validity and should already give you some ideas about audio capability/ levels, etc.

To give you another simple implementation, I've linked to a post I wrote (including the electronics and code) on my blog here.. http://majordecibel.blogspot.com/2011/02/back-to-basics-reading-in-line-level.html

Basically, as mentioned, the arduino ADC reads 0-5V signals. The signal you are passing it would swing +/- about 0V. This means feeding it directly will clip the negative values; you'll just get the positive ones (not recommended, but you could go with it depending on your application).. An op-amp (also mentioned above will help - I think that one may also have a 2.5V bias on it, as I will describe..) if you tune it properly to scale the analog signal can also help to get maximum resolution (feeding in a larger analog signal that does not clip lets you take advantage of your full 10 bit sampling precision). Alternatively (simpler, but not quite as good) you can just turn the volume all the way up. You won't be using all 10 bits since it won't swing all the way up to 5V, but you will get enough to do something.

Anyways, without DSP related considerations to sampling/ anti-aliasing, etc, the key is that you want to bias the ADC pin to 2.5V using a voltage divider, and isolate that point from your audio source using a capacitor that will pass audio frequencies (4.7-10uF should be sufficient). That's three components; two resistors and a coupling capacitor. This lets you feed in both the positive and negative parts of the waveform. Input signals that are negative will swing the bias between 0 and 2.5V; Input signals that are positive will swing the bias between 2.5 and 5V.

In software, you can then subtract 512 to get your "negative" values. You can print this to the serial monitor to verify what's going on.

*Note: The code I included also has an "offset" value. You can calibrate this manually. You want to choose it such that after subtracting 512 you get 0 (the case when input signal is 0, so you just get the bias voltage). It may deviate from this if the voltage divider between the resistors is not exactly 2.5V (because there are inherence tolerances in the resistor values). Using larger resistors is fine - you are trying to establish a voltage bias; this helps to limit current and therefore power drawn from the supply... and given a fixed tolerance will result in less deviation of the bias point from Vcc/2 or 2.5V..

I could go a bit further, but I hope this will help, along with the posts above..

Have fun!
12  Community / Exhibition / Gallery / Re: LED Music Visualizer on: February 15, 2011, 05:44:36 pm
Hey that's awesome! I took a look at the video and your blog - well done. Thanks for the feedback smiley
13  Using Arduino / General Electronics / Re: USB Power on: February 11, 2011, 02:36:33 pm
Ok thanks to both of you - I will try as a starter just running the USB 5v directly to the Arduino Vcc pin (this would not be an UNO board, or whatever).

This seems like a simple, inexpensive, and safe (though current limited) method of powering a custom board.

14  Using Arduino / General Electronics / USB Power on: February 11, 2011, 01:20:30 pm
Noobie question:

If I want to have a standalone board with an arduino chip/ oscillator, can I just use USB power directly with the right connector (USB +5V directly to Arduino Vcc)?

That is, is USB power regulated (from the computer, or one of those AC/USB wall adapters), so a separate voltage regulator would not be required on board?

Thanks!
15  Community / Exhibition / Gallery / Re: Arduino controlled VU-meter in boombox on: February 11, 2011, 12:49:57 pm
Looks cool. I like the enclosure.
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