Ingredients list:
- piezo plate(s)
- 1M ohm resistor
- Arduino board
- wires
- speaker(s)
- trampoline
After researching for something interesting and yet easy enough for me (a beginner) to handle, I started off trying piezo as a blow or knock sensor.
I bought various components like resistors, capacitors and a transistor-amplifier, which were suggested by the blow sensor project. But this “knock” example from Arduino official site is apparently simpler! I then switched to this minimal option for both aesthetic and practical concern.
Schematic:
I used the code and connected a piezo and a 1M ohm resistor as above with Arduino. The first trial was failed however. Thanks to Samson for pointing out my problematic soldering! One of the two wires should be soldered to the middle patch! Not both wired to the rim..
So the knock sensor finally worked! You can see serial printing of the word “knock” whenever a knock is sucessfully detected. The sensor is pretty acurate when used on a solid flat surface.
I loved the idea of collective intelligence even more when I happened to find a course outline by Mr. Jonathan Grover! He is a new media artist and teacher himself and is super nice to give detailed replies to my emails. The files he shared are instant fix for MAX/MSP to talk to Arduino (or vice versa)! And the creator of this MAX/MSP patch is just as generous as Jonathan! JoelisRich, another great person who’s showing his tutorials on YouTube, is very helpful too! My Theremin-Trampoline patch was made based on his theremin tutorial.
In the next test, I soldered long wires to another little piezo, and placed the cushion about 3 meters away from laptop. I have to admit that my obssession with piezo plates is irrelevant to technical issues. I love them simply because of how minimal, organic, wise, zen, etc.. they APPEAR to be! Using it with such long wires and hence losing signals did worry me at first but, the result was surprisingly good! The piezo works as a vibration sensor here. When triggered signals will be sent to MAX/MSP, and “wicked awesome delayed sci-fi noise” will be generated!
From the following videos, you’ll see the finalized theremin-trampoline.
I changed the input from analog pin 0 to pin 4 and finally pin 3 in order to get more dramatic effects. They can be occasionally hyperactive once, but lazy the next time.
Those two speakers can organically stick to the rim of trampoline because of their magnetic nature.
Again, many big thanks to Jonathan Grover, JoelisRich, Samson, Kev Wong, Eric Wong and Jan Fung for making the project possible!
Thank you for watching!
