2016-08-31 (W) Clockwork Theremin

Musical instruments, especially electronic ones, fascinate me. Music is such a mature art form, possibly the oldest. Music captivates me even though I have no talent for it. Before this blog I built a Guitar Hero guitar that would play actual music, not prerecorded, and a Theremin-like device that was fun but ultimately disappointing. It sounded like a firetruck fighting a brass trampoline.

My first attempt at a Theremin used inexpensive ultrasonic distance sensors but tried to output sound through a DIN MIDI output. Unfortunately MIDI was a poor choice. MIDI is great for sending single notes and bending them a little whereas a Theremin relied on a single note infinitely modulated while changing the volume.

If you looked through eBay it would be easy to find lots of simple devices called Theremins but the cheapest ones are just a light sensitive resistor that changes the frequency of a 555 timer outputting a sine wave. That’s another thing that digital circuits don’t do well, sine waves.

All these cheap ways of bending a sine wave stuck in my head and got me thinking about using a couple digital potentiometers to control frequency and sound. This method could hack together the cheap ultrasonic sensors, a cheap controller, digital potentiometers, and cheap “Theremins.”

Enough background.

The last completed project of Year 02 was an OpenSCAD program which generated spur gears. It was a good program for the most part but it lacked some important things which I had programmed into my first attempt at gears that used triangular teeth. In my triangular tooth gears there was an option for creating spokes. The program was smart enough to fill in the whole gear if less than two spokes were declared.

These two programs were integrated so the spur gear program had the option of adding spokes. Since these gears will probably be made out of wood it would actually be easier to build the gears without cutting the interior. Spokes were originally programmed so gears could be printed with a minimum amount of plastic.

A rough sketch was drawn so the gears could be arranged and sizes could be estimated. Once the program was written it was a simple matter to arrange the gears roughly how I liked them based on the sketch. Gears which could share an axle in the model should be assumed to be a two-tier gear. The largest gear will only have half of the teeth produced. This will be the gear connected to the potentiometer and the slowest moving. By making it with only half the teeth it will be more apparent when it moves which will be important since it will be moving according to the position of the player's hand.

Rough sketch

3D Model based on rough sketch

A full-sized PDF was created, 48” x 60”, in order to print the gears. The largest gear was intended to have a diameter of nearly two feet. These PDFs were also broken into three 36” x 24” sheets. These pages could be scaled and the gears would still work so long as the pages were scaled uniformly. All the files for these gears have been included in a single download.

All the gears together


The rest of the posts for this project have been arranged by date.

First time here?

Completed projects from year 1.

Completed projects from year 2.

Completed projects from year 3.

Disclaimer for http://24hourengineer.blogspot.com/

This disclaimer must be intact and whole. This disclaimer must be included if a project is distributed.

All information in this blog, or linked by this blog, are not to be taken as advice or solicitation. Anyone attempting to replicate, in whole or in part, is responsible for the outcome and procedure. Any loss of functionality, money, property or similar, is the responsibility of those involved in the replication.

All digital communication regarding the email address 24hourengineer@gmail.com becomes the intellectual property of Brian McEvoy. Any information contained within these messages may be distributed or retained at the discretion of Brian McEvoy. Any email sent to this address, or any email account owned by Brian McEvoy, cannot be used to claim property or assets.

Comments to the blog may be utilized or erased at the discretion of the owner. No one posting may claim claim property or assets based on their post.

This blog, including pictures and text, is copyright to Brian McEvoy.

2016-08-26 (F)