Ocean Sound Synthesizer
This fun project synthesizes the sound of the ocean surf. I designed
and built this project in 1990.
The circuit consists of two 31-bit linear feedback shift registers that
clock at 150KHz and 150Hz, respectively. The first LFSR generates white
noise and low-pass filtered white noise. The second LFSR is low-pass
filtered and used to amplitude modulate both noise components from the
first LFSR. The signal is amplified and drives a small speaker.
The use of digital techniques means that the rise-and-fall sound
generated by the circuit is not truly random, but repeats with a period
of about half a year! Also, the circuit generates the same sequence of
sounds every time it is turned on.