Fixture for Artbot
While searching the
web for artbot ideas, I came across Ralf
Schreiber's "Solar Sound Modules".
Ralf Schreiber uses a solar powered 74HC14 hex inverter along with
different resistors, capacitors and a piezospeaker to make objects that
create sound. The sounds that are generated are simular to that
made by insects, frogs and other creatures found in nature. As I
experimented with his circuit,
I wanted to make a more permanent
fixture that would allow full adjustability of all the
components. Not only does the 74HCT14 inverter have the ability
produce sound with a piezo, but can also drive leds if enough power is
supplied to them.
Now I can experiment with different values of components till I get the
disired effect, then go ahead and build my object. Ralf Schreiber
calls these objects "Living Particles", a name fitting for circuits
constantly adjust themselves with the enviroment.
My Schematic for the Fixture
How it works:
The six inverters form three oscillators. The frequency of the
oscillators are set by the values of variable resistors R2, R5, R8 and
by the values of "C", externally selected capacitors. Interaction
of the three oscillators is achivied by inserting resistance at the
positive power lead with R1 and R11. As the three oscillators
run, a voltage drop across this resistance changes the output
frequency. A further load on this resistance is provided by
adjusting R4, R7, R10. As the inverters change state, current
draw between R4, R7, R10 will vary. When this circuit is
powered by a solar cell, each inverter will share it's demand for the
restricted power. This fixture was made to test circuits that
will be using external power sources, but can be applied to solar
powered circuits if power demands are respected. The 74HCT14 is
designed to work with voltages to 5 volts, while a CD40106 can operate
to 15 volts. Keep in mind the values of load resistors at higher
voltages. I selected values that are safe for voltages below 5
PDF of the schematic
Experiment on the proto board. A wee bit
messy and difficult to
document and reproduce.
Test fixture made up with the above
Alligator leads for selecting capactors.
Youtube Video. Hear what it sounds like.