Octave Theory/Design Day

An octave pedal, as the name implies, is a circuit that’s meant to increase or decrease an audio source by a full octave. Unfortunately, these circuits are also often incredibly complicated.
However, I’ve had an idea for an octave-up schematic for some time now, and I just recently got the chance to test it out!

Here’s an explanation of how the circuit works:

The circuit gets divided into four sections, A through D.

Section A does some basic regulation to the waveform, first normalizing and then amplifying it, as shown above… Nothing too significant, just some basic preparation for the rest of the circuit.

The second stage uses two diodes to divide up the positive and negative peaks of the wave, and separates it into two channels.

Section C does two things- first, the negative peak band is inverted, meaning both waves are positive. You can see that the two hold (roughly) the same voltage.

After this, the waveforms are mixed together, and we can see we finally have 440 Hz, twice the Hertz value of our input- in other words, a full octave! This works due to the way that waveforms work- When the negative peaks are set to positive values, the amount of pulses (the frequency) is effectively doubled.

All that’s left is section D, which normalizes the waveform and shapes it to look (and sound) something like the input.

Efficient Christmas light hallw(d)ay

Recently, the idea came about that in the main front-door hallway of my house, [my family] wanted to hang up some Christmas lights to replace the glaring overhead light.

Problem: There isn’t an outlet in the hallway. (And it’d be inefficient to plug and unplug the lights anyway, even if there was)

After some thinking, I came across the idea that, since the light bulb plug uses the same voltage as a wall outlet, what if you could just make an adapter of sorts? And, once made, you could plug in the lights, and turn them on/off directly from the wall switch!

Shortly afterwards, I started in to making it, and finished it in about half an hour.

Final Product:

Once made, I replaced this (crazy) contraption with the overhead light bulb, plugged in (and hung) some Christmas lights, and tested it out! Luckily, it didn’t explode, short, spark or injure! (I don’t have a photo, but take my word that it’s there)

Spared from laying about parts, I’m honestly amazed that in this case, form met function, and that it fit together so nicely.

Anyhow-

Cheers to the modders/scrappers/rappers/and builders,

Secoyatree

Analog algebraic sinusoidal band-pass filter spectrum encoder-decoder day (a.k.a. Vocoder)

For this semester, Max and I plan on building a vocoder from scratch.

A vocoder, put simply, is a device that filters an audio input (typically a microphone) in accordance to a second input (usually a keyboard). This is done by feeding the first source (the “Program”) through a series of ‘band-pass filters’– or ‘bands’ for short. Once the first input is separated and decoded, the second input (the “Carrier”) is analyzed and processed with a circuit to provide the amplitude levels for the program (An “Envelope Follower”). Finally, this spectrum of signals are mixed and re-encoded to a single output.

The vocoder adds a synthetic, artificial tone to the voice, as if the words are being spoken through a robot or an early voice module.

Here is one that Kraftwerk had custom built for them in the ’70s (and used in the album “Ralf und Florian“)!

Tremolo Day

Here’s something that I’ve been working on recently…
Tremolo is an effect or technique that involves the rapid triggering of a sound– you’ve almost certainly heard it before! When used properly, you can get great sounds out of it.

That’s the complete schematic for it (so far). I’ll try to explain how each part of the circuit works…

To(Tayda)day

Have we gone over this?

Probably not. Basic context:

When electronic parts are needed for a project, you could either go to Radioshack (convenient but expensive), or order them from online (cheap but slower). For the longest time, Max and I have had a hard time finding the best site to order from- whether it be because of part stock, pricing, shipping time, or otherwise. The main place we kept revolving around was Mouser (www.mouser.com), because they’re located just outside of Ft. Worth, making shipping cheap.

Extended Return of the Pizza Day

Apparently, the previous article was our 30th post. Hoorah!
Anyway, here’s some more of our summer shenanigans.

Arduino Keyboard
This was a project that I really wanted to finish, but was unfortunately postponed due to some… complications. (I’ll get into that later!) The idea was to create a tiny, MIDI compatible keyboard, using keys scrapped from a kid’s toy.

Return of the Pizza Day

We’re back! In celebration, I’ll be making a few posts about stuff we did over the break.

Arduino 16 Step Sequncer
Many of our projects came out of the greatness of the Arduino project. Essentially, the Arduino is a magical little board that combines aspects of circuitry and computer programming. The result is rather amazing- we couldn’t find anything that we couldn’t do with it! Secoya and I decided on making a rudimentary sequencer with the Arduino, which despite being a bit twitchy and resembling an IED, works rather well!