Friday, March 28, 2014
For Arduino Day 2014, I show how I solved the problem of enjoying wind chimes when there's no wind. Using an Arduino of course.
For a written transcript, go to How to make artificial wind.
Music under Creative Commons License By Attribution 3.0.
Intro/Exit: "Hot Swing" by Kevin MacLeod at http://incompetech.com
Incidental: "Feelin Good" and "Cold Funk" by Kevin MacLeod at http://incompetech.com
Today at the House of Hacks, I'm going to try to make some artificial wind.
Hi Makers, Builders and Do-it-yourselfers. Harley here.
Over the years we've been give a couple wind chimes that are really nice. They're tuned to specific chords to be really full and resonating. They've got some beautiful wood on them and they're just too good to put outside in the weather and get all beat up. So we have them hanging here in the corner of the living room. During the summer they work really well. We open the house up and the breeze comes through, particularly the evening breeze, they fill the house with nice chimes. During the winter we close everything up and we just don't get to enjoy them. We've tried using an oscillating fan and haven't really been able to get this to succeed very well. The fan itself is very loud and makes a lot of noise. And we haven't been able to get it adjusted so that it has the right amount of turbulence to ring the chimes in a way that sounds pleasant, it's either not enough or too much.
I've had an idea floating around in the back of my mind for awhile to do this electronically. I thought this was a good time to try to do this. March 29th is Arduino Day. It's hard to believe that Arduino's been around for 10 years, but this is its 10 year anniversary--10 year birthday. I thought this would be a good opportunity to do a project that featured an Arduino and also solved a problem that I have. So let's go down to the workshop and see what we can dream up.
The idea I've had floating around in the back of my mind now for awhile is to take an Arduino, connect it to a servo motor and on the servo motor attach a pulley. To the pulley attach some monofilament thread and connect the other end of that to the wind chimes. So, when the pulley turns, it pulls back the wind chimes and then it releases them and they can swing. The Arduino gives us the ability to add some randomness in there to pull it back different amounts, to release it at different speeds, things of that nature, to give us some randomness and hopefully give us a nice pleasing sound that we have some control over.
I think what I want to do is have a total of 12 inches that it pulls on the monofilament thread. And I want to do that in a quarter turn of the pulley. That means the pulley circumference needs to be 48 inches. To get the radius to make the pulley we have the 48 equals 2 pi R. We need the radius so we divide 48 by the 2 pi. Well pi is pretty close to 3 for round numbers and that gives us 48 divided by 6 which gives us a radius of 8 inches.
So let's go build this.
A thin strip of scrap wood fills the need perfectly for an ad hoc 8 inch compass.
I mark the boundaries of the center based on the outside dimensions of the cardboard.
The center of the circle needs to be inside these bounds.
And now just draw the circle.
I cut the cardboard freehand around the marks. I needed 3 disks in total.
Since this is just a prototype, proof-of-concept, scrap cardboard and some hot glue make fast and cheap building materials.
Mark the direction of the corrugations so when the disks are glued together they can be rotated 90 degrees to each other. This will give them some strength.
Three circles, one slightly smaller than the others will make a rough pulley.
I've found hot glue is a great tool for fast construction.
Now I need to find the center. If I'd been thinking I could have placed the other side up and had the hole from the compass already marking the center for me.
A dab of glue attaches a small servo.
The servo is mounted in a hole cut to its size.
A couple weights holds the cardboard tight to the motor mounts while some glue is applied.
A spare piece of Romex wire will work as a mounting bracket for the Arduino.
The wire just slides into the corrugations of the cardboard.
And holds the Arduino in place.
The circuit is simple. The servo connects to the breadboard. To connect the servo to the Arduino, the yellow data wire goes to pin 9, the brown ground wire goes to ground and the red power wire goes to 5 volts.
And it's ready to test.
Load the example servo to sweep a 180 degree arc and upload it to the Arduino.
Fail!! It worked a couple times and then stopped. Something broke. I had to help it get unstuck on one side.
So I needed to swap motors. The first one I tried had a 1.6 kg/cm torque rating and plastic gears. The replacement is rated for 3 kg/cm and has metal gears. It's also quite a bit more expensive.
So I used screws to mount it instead of glue.
I still used glue for the pulley though.
And this works much better. No manual intervention required.
A dollop of hot glue holds the monofilament string in place.
Another piece of bent Romex wire acts as a guide for the string.
Load a slightly modified version of the sweep example.
And a real test…
Yay!! It works!!
For a hacked together prototype, I'm pretty pleased with the way this turned out.
If you're interested in seeing this prototype turned into a finished project, let me know down in the comments below what it is you find fascinating about this project, what you'd like to see in a follow-up video, that type of thing.
Until next time, go make something. It doesn't have to be perfect, just have fun!
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Thanks for watching and until next time, go make something. It doesn't have to be perfect, just have fun.