Presto Electro

A couple posts ago I talked about "clipping". More specifically I talked about how cool it sounded, and how hard it was to find an audio representation of it. Well guess what? I had some free time this evening and I put together a couple of mp3s for your education and benefit:

Sine Waves

I'll be honest with you: Sine waves are boring as heck to listen to. They don't have any harmonics at all, so the sound they make is really quite uninteresting. For the purposes of this experiment, I've synthesized an F Major chord to give this mp3 at least a little interest. The waveform below is a visual summary of the component parts of the chord. You may listen to them by clicking on the picture!

Even with the harmonizing it is still pretty tough to hear. Below, I've doubled the frequency (raised it an octave) so it is a lot easier to hear:

Clipped Sine Waves

Thank you for enduring the sine waves. Here comes the good part! This clipped sine wave sounds awesome, and I am sure you can imagine the kind of impact some careful clipping could lend to a guitar sound. PLEASE BEWARE!!! The clipped wave is MUCH easier to hear! If you turned your speakers/headphones up for the sine waves, turn 'em back down!

Visually, the clipped wave doesn't look like much of anything. It certainly doesn't seem like it would be very much more interesting than the others. But our ears process sound waves in a way that interprets the "corners" of the clipped wave as a bunch of sounds interfering with each other.

If you play these mp3s in anything with a graphic equalizer, you can see a visual representation of this phenomenon: The clipped wave show up over a much higher range of frequencies than the sine wave does. Here are some extremely scientific animated GIFs for the mp3-player impaired:

I've been seeing a lot of movies lately. I'm not doing it on purpose, but sometimes every single person I know wants me to go see a movie with them, and I never turn down a trip to the movies. Last week I saw a movie almost every single weekday. Fortunately we had a lot of theaters to choose from, so I didn't have to go to the same one over and over again.

Tuesday Night: The Wolfman @ Denton Movie Tavern

On Tuesday night I saw The Wolfman at the Denton Movie Tavern. The movie was hilariously terrible and/or terribly hilarious, but you could probably guess that from the title. The Movie Tavern was great, though. This was my first ever trip to the Movie Tavern, but I've wanted to visit for ages. I'm a big fan of food with my movies, and theater/restaurants (Theatrestaurants?) are pretty much the best way to combine the two. (I am not a big fan of after dinnermovie dishwashing.) I didn't have any food this time (I had a big dinner okay), but the Movie Tavern had a great menu, and a surprisingly cool lobby area. The real advantage to the Denton Movie Tavern is the LUXURIOUS foot-room in-theater. Each row is separated by a long thin dining table, so its almost impossible to accidentally kick the person in front of you in the head/arms.

Wednesday Night: Flow @ The Media Library

The University of North Texas campus isn't a theater in the conventional sense, but it is nevertheless a great place to catch a cool movie or two. A cursory glance at announce.unt.edu reveals everything from thought-provoking documentaries to totally brainless blockbusters. If you live up here, I recommend subscribing to the Arts and Entertainment RSS Feed to remain abreast of the entertainingest bits of UNT. Personally, I'm subscribed to the omni feed that lists every single announcement from everywhere on campus because I love always having something to do.

Thursday Night: Crazy Heart @ Cinemark 14

Ah, Thursday nights at the Cinemark 14… The Cinemark is a totally regular, normal theater. It's clean and nice and the seats are comfy, and everything is well maintained. It doesn't have quite as much personality as the other places, but it does have plenty of screens. It's also a tiny bit out of town. It's only 5 miles from the square, but five miles is a long way when everything you could possibly want is less than three miles away in Denton. On Thursday nights, though, it is definitely worth the drive. Thursday tickets for students are only $3.50! Nice!!! The movie wasn't particularly amazing or anything, but I've only myself to blame for that. I've already seen all the good ones.

Electronics I is a very mysterious title for a class. When I enrolled in it last semester I didn't have any idea what to expect. I could have looked up the course summary in the online course catalog, but I like surprises. I also completely forgot about the course summaries in the catalog until just now. Yeah.

Anyway, I'm taking Electronics I this semester, and the second unit is all about Diodes. The first unit was Op-Amps-- fascinating, but probably too complex to summarize in a single blog. Diodes, on the other hand can be represented by this very simplified model:

The "Ideal Diode" works like a little switch. It turns "Off" when the current tries to flow one way, and turns "On" when it goes the other direction. It's like a turnstile or a one-way street, except instead of people or cars, it organizes electrons. This behavior allows for all sorts of clever manipulation of current. Rectification was the focus of last week's class, but diodes can also be used for things like diode logic and audio manipulation.

Whenever an electronic component can be used to manipulate AC signals, I start imagining what sort of impact these things could have on audio signals. And I'm definitely not the only one. Non-linear components are golden when it comes to distortion!

Here is a great example of diode use in action. This circuit takes advantage of the fact that real (non-ideal) diodes need a little kick-start before they flip "on". If you apply more than zero, but less than (usually) .7 volts to an LED, it stays off. If you go over that threshold, if flips "on". In this case, it flips on and connects the guitar signal to ground, and chops off the top of the peak of the signal.

I've found approximately a million articles about clipping and distortion, but NONE of them have sound!!! I think I'm going to have to bring a guitar into the lab tomorrow…

I love a good infographic. They look cool, they're educational, and they're huge time savers. A well designed infographic can illustrate a huge wealth of information at a glance. I've always felt that infographics were pretty neat, but I haven't had a good reason to mention them. Until now.

This semester, I'm taking Professional Presentations. The first chapter of the book has a lot of information about the history of presentations and graphics and colors and everything, but it also has some SWEET infographics. Check out this one:

If you are ever confronted with an upset dog, just turn to page 50 of Edward Tufte's The Visual Display of Quantitative Information, and use this handy graph to figure out how the dog REALLY feels!

There are plenty of excellent charts and graphs in this book, but the examples of what NOT to do are so much more interesting than the proper ones. As a case in point, check out this graph of inclinations of planetary orbits from the Middle Ages:

Back then the sun bounced up and down at random, apparently! In the artist's defense, though, this is the oldest known example of a time-dependent plot. It didn't really catch on. The next example wasn't seen until 800 years later.

These days, we are SURROUNDED by information. A huge amount of data can be construed as relevant to any given topic, and it is easy to come away with even less of an understanding than you started with.

It takes a special kind of smarts to turn this intractable bulk of information into an image that is both easy-to-understand and easy-on-the-eyes.

The University of North Texas has a TON of computer labs. The General Access Computer Labs (GACL) system has 14 labs peppered throughout the campus, and that's not even including the myriad of labs tailored to less-than-general access. Every lab comes with Microsoft Office 2007, Photoshop, and a selection of web browsers.

But most labs also come with a little extra. The Technical Communication department has a Technical Communications Lab with software that is particularly great for technical writing, and the College of Music has its own lab with software more appropriate for enhancing the ability of any musician. The list goes on and on, but if you're wondering about a particular program, I recommend consulting this page.

The Electrical Engineering Department has a boatload of specialized labs. In Digital Systems Design, my computer station sits next to a tall stack of analytical equipment and power/function generators. The computer itself is loaded with all kinds of professional software for digital design, and Xilinx is the program that I have (thus far) used the most.

In Digital Systems Design, most of the projects are programmed on to Field-programmable gate arrays (FPGAs). Prototyping digital circuits onto a breadboard is really fun, and it is a great way to realize schematics, but it can be a HUGE PAIN to troubleshoot. If your circuit doesn't work on the fist go, every single wire could be a potential point of failure, and figuring out where to test first is often puzzling.

With FPGAs, you can skip the messy wiring bit. Once you've worked out the behaviors of your project, you just need to translate it to VHDL code. Writing the code for it is fairly straight-forward, and Xilinx helps out along the way with syntax checking and simulation. You can even test your design with a "test-bench" script that will apply virtual inputs to your simulated system, and then display the outputs. Test-benching is a difficult concept to explain, and I apologize for that last sentence. Here is a picture of the results from my first test-bench of the year:

The two inputs, 'a' and 'b', were provided by my test-bench script. The resulting output is 'f'. Can you guess what this circuit does? Email me if you want a hint! :)