I got the WAV trigger to work. Turns out I had to convert the files in Audacity, remove all the metadata, and change the settings to 64kbps and 44.1khz... which for some only worked in Audacity and not Adobe Audition.
I soldered all of the microswitches to the board and mounted them on a piece of foamcore to keep them in place.
My battle station! I have a love/hate relationship with soldering.
Soldering all these little switches so close together was pretty difficult. I also may have destroyed some of the ports trying to get the header pins out (oops). You'll see that in the second photo I accidentally soldered a switch on backwards. Lots of rookie mistakes from being too excited...
Here's a short demo of the working components:
Now that that's finished, I found a few pitfalls. I used recordings of a xylophone, which has a nice pleasant sound. However, it's not very useful for sustained notes. If you hold down one of the keys it just repeats the plucking sound in a loop, which doesn't work too well in this system. I'm going to have to experiment with other sounds or simply sine waves.
I also prototyped a few options of different tracks:
A straight track (like in my older prototype from last year)
A topographic track with undulations - this could be interesting in mimicking crescendos/decrescendos or even song structures. Not sure if that's very necessary though.
A round track - this would be great for loops of music, and in terms of round tracks is probably the only feasible one for me to successfully produce. Even then, it's going to be difficult to figure out how to get the track and the switches to line up (do I angle the row of switches?). Hopefully I can get this nailed down this week.
I made a little "schematic" of the internal components and the track:
This is a side view of where everything on the inside has to be placed. The speaker is on the back of the car so that the user's hand doesn't muffle the sound when pushing it along the track. The battery is on the bottom for easy access to replace/recharge. The off/on switch is also on the bottom, something I added last minute because I realized I didn't have a way to turn the system off and on without taking out the battery (oops). I'm going to have to CAD an effective mounting system to make sure all these pieces can just be set into the body of the car easily. That's my next step!
This is the track in its linear form, which is how it was for my original design. Right now, I have an F major scale, mostly because I liked the sound of the F scale on the xylophone. This is subject to change. The track itself will be entirely analog - the only electronic components are in the actual car.