Michael Ribiat playing the interactive installation instrument created as a group project in the last class. The instrument transduces sound using handmade Piezoelectric transducers and the voice coil of a speaker (from which the diaphragm of paper is removed so it no longer moves air to make sound - it becomes a magnetic transducer). These vibrate a sheet of copper or steel suspended from springs (to allow free mechanical vibration). The sound is then picked up via piezoelectric pickups and magnetic pickups - amplified in my preamp (design below) and sent to speakers. The instrument allows one to "play" with the transfer of energy and resonance to alter and create new sounds. It also functions as a percussion instrument. It is highly interactive, intuitive, tactile and sensitive - yet simple enough to build from scrap in a half hour.
Sylabus (PDF): celsylabus.pdf
Class Survey (to ascertain basic technical experience): survey.pdf
Class 1 Presentation & Notes -- Basic Electricity Knowing Your Components Etc
*Note to people not in the class: By themselves, these resources are incomplete. These notes are part of a class, and some theories and ideas are greatly simplified in the notes here.
Class 2 Notes and Resources --
We built a simple oscillator with schmitt trigger integrated circuits (chips):
The following chips can be used:
4584
74C14 (74HC14 is okay, but will not work with 9v -- use 2 AA instead)
45106
Generally, we used a 10 to 100k Potentiometer and a .1 to 1 uF capacitor.
The pin diagram for the chips above is:
VDD = Positive power supply (connect it to the battery +)
VSS = Ground (connect to the negative battery supply)
With this pin diagram in mind, we created this circuit:
I also demonstrated a modulator constructed from a 4070 XOR Gate.
The pins on that chip look like:
Power this chip the same way you would for the schmitt trigger chips (notice VDD and VSS in diagram). Remember, the dimple or notch in the chip always goes on the left (to keep you from using the chip upside down).
TWO inputs go into the XOR gate and 1 comes out (ie. two different signals into pins 1 and 2, one coming out of pin 3)
The XOR does not require any additional components like resistors or capacitors.
A 4093 NAND gate is another option for modulating sound or creating a different type of oscillator.
Datasheets for these chips can be found in PDF form at http://www.alldatasheet.com/
Datasheets include lots of information about the ICs and the pin diagrams like above...
We breadboarded these circuits, but we can also transfer them to soldered "perf boards" later.
a 4040 chip can also be used to create a "sub-octave" effect, by dividing the frequency by 2, 4, 8, 16, etc...
We also demonstrated a photocell used to control frequency. The same photocells can be used to change volume as well (we'll try that later).
If you wish to order integrated circuits, I recommend http://www.jameco.com/ or you may be able to find a lower price at http://www.goldmine-elec-products.com/
Electronic goldmine is also a good source for inexpensive beginner kits.
Breadboards can be purchased at any electronics store including those above.
Class 3:
Lecture notes - click here...
Supplemental Info -
I demonstrated the power of this circuit, so I'll give you the instructions (for the more adventurous)...
Here's the simple battery powered pre-amp I use to even out impedance issues and make piezos full-frequency and not tinny sounding. The TL072 opamp is a common, cheap, low noise opamp. Two opamps are on one chip. If you want four, use a TL074, which has 4 per chip. This circuit does not amplify the signal level, it only "follows" it and smooths it out, creating a low-impedance, line level signal from the piezo. If you make it, don't forget to provide power to the opamp, even though that is not shown in the schematic.
This circuit SIGNIFICANTLY improves bass response and smooths the tinny highs of an unaltered piezo.
A TL092, TL062 or TL082 could also be used.
| Creative Electronics Final Group
Installation, Sound Fest... Bring
your oscillators, ring modulators, piezos, bread boards and sound
making gear. We are going to hook them all up and resonate them through
a big ol' piece of steel and some other "resonators".
Useful items to bring: Piezos - Big and small. PVC pipe - no longer than 3' please. Speakers - large and small (must be unenclosed, bare speakers) large and small Oscillators, ring mods and other circuits you've been working on. This should be chaos, but of an interesting, haphazard variety. It should also be fun. -Lorin |
Basic List of Useful ICs:
CMOS ICs:
4584 Schmitt Trigger
4093 NAND Gate
4040 Divider
4049 Inverter (can be used as a basic amplifier)
4070 XOR Gate
Others:
LM386 - A small chip that acts as an audio amplifier.
7805 - A voltage regulator which converts higher input voltages to 5V
OpAmps:
741 - The classic opamp
TL072 - A dual, low noise opamp
TL082 TL092 - Variations on the TL072
LM324 - Single Supply opamp
Misc:
Photocells, pieces of metal, batteries, switches and buttons.