“An electronic sound and light sculpture
cwymriad is a ring modulation based sound sculpture which displays the output signal on an 8x16 LED matrix.
‘cwymriad’ is based on a dual ring modulation circuit in which the ESP32 creates both the carrier and modulation signals. The square wave output of the ESP is filtered down to something resembling a triangle wave and combined in the ring modulator before the resulting signal is sent through an echo effect, and then sent back to the ESP32’s internal ADC so that it can be displayed on the LED matrix.
I’m using an MCP4251 digital potentiometer to function as a sort of voltage controlled amplifier, except that the control voltage envelope is created in the code of the ESP and transferred to the digital pot via SPI. Ring modulation in itself is of course quite similar to amplitude modulation, but here the digital pot is doing the volume control, while the ring modulator is creating the bell-like sounds out of only a couple of oscillators. I’m using a PT2399 echo chip to give some depth to the sound, and the whole thing is amplified by two bridged LM380 chips, while the LED matrix is driven by a few MAX7219’s.”