ITP Blog
Energy
Final Project - The Kinetic Wah
I had this idea in class just before I had to talk about my idea, something so spontaneous. I had always wanted to tap into guitar pedals and understand what was going on, I have done simple dsp stuff with software but never hardware, so I was really excited to try that, the energy aspect of this project made sense as kinetic for me, because we already operate these pedals with our feet so much, that's a lot of kinetic energy wasted that could be turned into electricity.
I started by looking into what were my options in terms of dsp, I could go down the microcontroller route but it just didn't seem feasible with kinetic, because of how insignificant it can be and how much power even the simplest microcontrollers need to operate, also if I wanted a better quality audio I had to choose from higher models which would require even more power, and anything digital doesn't like voltage coming in and dropping, which will inevitably be the case with kinetic, unless a battery of some sort is also implemented.
This lead me down a research on analog circuits, most wah circuits I found online had an inductor, which I wanted to avoid, so I found one schematic which didn't require an inductor to operate called the Colorsound Inductorless Wah. The first prototype I made on a breadboard was surprisingly working after a few minor debugs!
As my next step I wanted to try and understand what each bit of the circuit was doing to the sound, I found out that the fixed resistor before the potentiometer that controlled the wah frequency range, I experimented with different values to get the tone that I thought sounded better.
Next I had to power the circuit using kinetic energy. I realized this circuit needs very little current to run, around 10mA, so that was good news. I made my own full bridge rectifier circuit using four diodes and used the stepper motor I used previously for my kinetic energy, since it produced enough power I didn't want to go through the process of making my own generator.
I connected my stepper to the circuit and the first thing I noticed was when I moved the stepper I could hear it turning through the amplifier. Adding a capacitor reduced the noise significantly while storing some electricity so that the circuit does not die completely after the stepper stops turning.
I personally can hear a difference in tone when it's powered using a power supply vs kinetic powered, but that's to be expected, and I don't think one is necessarily better than the other, but maybe the intended tone is the one with a power supply.
I soldered all the parts on a protoboard to get rid of loose wires and clicks and noise.
At this point I think the basic concept is there and it's so surprising to me that it works. My next step is to build an enclosure so that it holds all of the parts together and a gear system that turns both the stepper and the potentiometer with the pedal movement, I'm experimenting with wood and also 3D modeling for now.
Also I'm open for any name suggestions!
I 3D printed my model but the dimensions did not align with my components so I had to improvise a little and mount the motor in the side. I drilled holes for input and output jacks because I forgot to put holes in my 3D model.
The final thing works as expected, even a slight movement of the motor generates enough power for the circuit to function. I am so excited to dive deeper into guitar effects. This was my first time ever putting together a pedal circuit. I enjoyed every bit of the process and I hope to reiterate and make it better. I think I can come up with a better enclosure and fabrication.