July 16, 2014
Circle Draw is an instrument that plays with Persistence of Vision (P.O.V) to draw circles with a single laser diode. This creates a sharp drone sound where the pitch is controlled by the speed at which the circle is drawn – the speed of the motor.
A laser diode is lined up closely with a small rotating mirror that is at an angle to the laser. When the motor spins the mirror the laser dot is “drawn” faster than the eye can see the difference and we start to see a continuous red line and we can hear this by placing a solar cell in the path of the light. To get more intersting sounds it is good to blink the laser diode (either randomly or at a controlled rate) to break the constant drone. Added to this is the use of a servo to “twitch” the laser diode across the face of the mirror. Try changing the angle at which the light crosses the solar panel for subtle changes in sound.
To build the circle draw instrument you will need:
Here is a short video demonstrating the use of the circle draw: