Visualizing The Fourier Transform

If you do any electronics work–especially digital signal processing–you probably know that any signal can be decomposed into a bunch of sine waves. Conversely, you can generate any signal by adding up a bunch of sine waves. For example, consider a square wave. A square wave of frequency F can be made with a sine wave of frequency F along with all of its odd harmonics (that is, 3F, 5F, 7F, etc.). Of course, to get a perfect square wave, you need an infinite number of odd harmonics, but in practice only a few will do the job.

Like a lot of abstract concepts, it is easy to understand the basic premise and you could look up any of the mathematical algorithms that can take a signal and perform a Fourier transform on it. But can you visualize why the transform works the way it does? If you can’t (or even if you can), you should check out [Mehmet’s] MATLAB visualization of harmonic circles. If you don’t have MATLAB yourself, you can always check out the video (see below).

Over-the-top Hackerspace Donation Box Brings Out The Brony In You

If you’re going to pass the hat for donations to your hackerspace, you might as well add to the value proposition and give potential donors a little something for their generosity. And what better way to cash in than to channel the inner Brony in your donors with a My Little Pony themed dollar-bill vortex box?

Sick of the boring cheezy-poof jug her hackerspace was using as a donation jar, not-a-Brony [Michelle] was inspired by the CRASH Space mascot Sparkles, pictured left, to build a new box that will maximize donations by providing donors with a multimedia extravaganza. The Plexiglas box, resplendent with laser-cut acrylic hearts and spangled with My Little Pony stickers, is fitted with a sensor so that donations trigger an MP3 of the MLP theme song. A scrolling LED marquee flashes a gracious message of thanks, and to complete the experience, a pair of fans creates a tornado of the fat stacks of cash in the bin.

Putting a little [Twilight Sparkle] into your donation box makes good financial sense, as does providing incentive to deposit bills rather than coins. This project reminds us of our recent post about a custom claw machine which could be leveraged as a value-added donation box – just add a coin slot. And rainbows.