Final round, for now…
In the last two days of the workshop we learnt how to control a switch with a NOT door oscillator and how to build an oscillator with modulation. Basically it is made with several NAND doors (that is an AND door witch the exit is linked to a NOT door, there fore it gives to opposite of the logical sum of the two entries… ok… technical crap…) built in a cascade form. The NAND door has two entries; in this case we use one as a start-up control and the second one as a pitch control. The start-up control can be seen as an automatic switch, when you have power the NAND door is ON and it works, when not, it is OFF and it stops to work. The pitch control works exactly the same way as the previous oscillator; a variable resistor controls the frequency.
Switch controlled by a NOT door oscillator:
NAND door oscillator controlled by 4 light sensitive resistors and a potentiometer:
Final production:
The difference between this oscillator and the previous one in multiple exit addition is the output shape. The NOT oscillator adds the signals, so we have a sound that is the result of a sum. The NAND door modulates the signal, which means it changes the signal shape. With constant resistors you may not see the difference between both oscillators. But when you start to vary the resistances, you’ll see that the way the sound changes is different.
The last day of the workshop was used to solder the final circuit. We have made a small demonstration for the people who were in my art academy and we cleaned up all the mess we did the last six days.
I will end up this post with a video from a Electroacoustic instrument called Rectable :
This instrument works with several oscillators (controlled by the computer) in signal addition mode and signal modulation mode.
