If you’re into electronic music, you’ve most likely heard of the stepped tone generator originally conceived by Forrest Mims — or its close cousin, the Atari Punk Console. These devices can vary the frequency of noise emitted from a speaker, as well as change up the duration of each square wave that forms the audio frequency you hear.
Varying these two musical elements lets you create a wide array of sounds by itself, but audio hacker lonesoulsurfer decided to take things to a new level and added a four-step sequencer. This enables his new device to play four different tones controlled by four individual potentiometers. Three more pots below these allow for tone adjustment among all four steps, along with pitch (frequency) of each, and sequence speed. Notes can even be turned off individually to add extra syncopation.
As seen in the video below, it looks like a lot of fun to play, but what really sets this build apart is that lonesoulsurfer used only integrated circuits; no Arduino, Raspberry Pi, or other programmable system. A 4017 sequencer IC takes care of stepping, while the 556 is used in much the same way as Mims’ original system. Step speed is taken care of by — what else —the venerable 555 timer.