As a test for higher loads on the output circuit we connected a servomotor and controlled its rotation via Arduino. In order to achieve a higher current we built up a transistor circuit with an additional power supply:
The video below shows the rotation of the servomotor controlled by arduino microprocessor.
The next step was to test our sensor devices such as a photoresistor, a force sensing resistor and a hall effect sensor. First we tried to apply them as digital sensors. Therefore we set up a voltage divider with the sensors as adjustable resistance. With some of the resistors it was quite well possible to achieve a analog signal whos range covered digital 'on' and 'off' strength. In a next step we figured out the range of analog input signal, their accuracy and controllability. The circuit diagrams for those sensors can be seen below.
The analog application of the photoresistor and the force sensing resistor as a sensor can be seen in the video below.
In the next step we faced the challenge to write analog input signal to EEPROM and read it with the scope.
Now that we had become familiar with the arduino i/o ports and the coding in arduino c-code we wanted to access its pins through LabVIEW. We faced some data conversion problems (string vs byte) but finally fixed them and we were able to control the frequency of a square wave function at a digital output port. The program for this function had been loaded to the microprocessor before. We also managed to read analog input signals through LabVIEW. An example of how to control the microprocessor through LabVIEW can bee seen below.
At this point we had all necessary knowledge about our devices to build up a "Thevenin-like" musical instrument. We programmed a connection between analog input and output ports in order to be able to control a speaker by adjusting the above mentioned sensors.
Here you can watch the video of our final Thevinin instrument:
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