ESE350 Wrap-up

Here is the link to our final report on the Mini Tonewheel Organ: ESE350FinalReport.pdf

Here is the link to our demo video: https://youtu.be/ukaQK6Y91U8

And finally, here is our GitHub repository: ESE-350-MiniToneWheelOrgan

Thanks to Professor Mangharam and all the Spring 2015 ESE 350 TAs.

Deliverables for the Final Push

To be completed by Monday:

• Laser cut and assemble mechanical housing
• Be able to perform basic waveform synthesis using the PSOC

To be completed by Wednesday:

• Assemble magnetic pickup and use gears to induce current in the pickup
• Build amplifying circuit for the signal coming out of the pickup
• Recreate analog signal through the PSOC

To be completed by Thursday:

• Repeat above steps for multiple tone wheels and be able to play multiple tones at once
• Decrease latency in motor actuation and be able to control motor speed using a series of       pushbuttons that correspond to motor speeds in the mbed code

To be completed for the final demonstration Friday:

• Add pushbutton functionality 

Projected Baseline and Reach Goals

So far we have our motor software working, and we're very close to completing a single tone-wheel rig.

The picture above is a photo of our motor mount.

Here is a photo of our tone wheel constructed from a steel band saw-blade wrapped around a laser-cut disk.

For our motor driving software, we made the decision to move the speed actuation component to an mbed to be able to free up more power on the PSoC board for signal processing.

In the next few days, we will construct the magnetic pickup fixture, and write the audio signal processing software for the PSoC. For our Baseline goal, we plan to have the single tone wheel apparatus up and running. The tone wheel will be producing one constant analog audio signal that will be digitally pitch shifted by the PSoC to support a range of notes. For our Reach goal, we would like to implement MIDI interfacing to support a MIDI keyboard for user input. Also, we would like to produce more analog signals for better audio quality by either adding on more tone wheels of different sizes or writing code to change motor speed as the user presses different notes.

Progress Update

Progress has been slow since we've had to redesign our tonewheel set up. We realized that ferromagnetic gears are expensive/not readily available, and machining our own wheels out of sheet metal would be a time intensive process that would require several hours of constant supervision for each wheel.

Thus, we came up with the idea of using saw blades to generate a sine wave. We tried running a circular saw close to an electric guitar humbucker pickup, and we were able to observe a sine wave on an oscilloscope. Unfortunately, the staff of the lab we were working in quickly kicked us out when they saw what appeared to be two kids about to saw an entire electric guitar in half so we were not able to take a photo of the sine wave or measure its frequency.

Using our own motor, we plan to more thoroughly test a smaller scale circular saw blade as well as a band saw blade. The apparatus for the band saw blade involves wrapping the saw blade (similar to the one pictured below) around an acrylic laser-cut disk. The teeth on the saw blade would be pointing towards a magnetic pickup. As the disk spins, it should theoretically generate a waveform similar to a tone wheel. We can even create multiple disks that would generate different frequencies at a single fixed motor speed by varying the radius of a disk. The only caveat with using saw blades is that an element of danger is added. There would be saw blades spinning with speeds of 1000 RPM+ so we need to consider some protective measures in case of failure. Perhaps some shielding around the entire tone wheel apparatus will be required.

Original Proposal

Just to have an online copy of our original proposal: Link

Prototype Model

Here's a quick SolidWorks model I made that shows how we plan to test our tone wheel idea.  It consists of a gear freely attached to a vertical post such that it can spin in front of a pickup (the brass-colored blob).  We will place magnets on the gear in different locations and see how the combination of number magnets and their placement affect the sound produced by the pickup.