Nerdy sound generator stuff 
Inside the red box is what is actually making the sound - a home-brewed oscillator, being prototyped on a "breadboard." It accepts control voltages that determine what frequency of sound to output. An increase of 1 volt shifts everything up by 1 octave.
The green box is a sequencer. It sends control voltages, configurable per step, to the oscillator.
Blue box is a bench power supply - crude for this purpose, but easy to use for testing. It is spitting out both + and - 12VDC.
Orange box is a bench multimeter, connected to monitor the + voltage output.
Purple is the oscilloscope, monitoring the audio spit out by the oscillator.
And bonus: that sequencer talks MIDI, and the program running on the computer is receiving MIDI note data from the sequencer, and shows the notes being played in real-time. It works the other way around, too - stop the sequencer, and notes can be sent from the computer to the sequencer, thus driving the oscillator.
    
  Inside the red box is what is actually making the sound - a home-brewed oscillator, being prototyped on a "breadboard." It accepts control voltages that determine what frequency of sound to output. An increase of 1 volt shifts everything up by 1 octave.
The green box is a sequencer. It sends control voltages, configurable per step, to the oscillator.
Blue box is a bench power supply - crude for this purpose, but easy to use for testing. It is spitting out both + and - 12VDC.
Orange box is a bench multimeter, connected to monitor the + voltage output.
Purple is the oscilloscope, monitoring the audio spit out by the oscillator.
And bonus: that sequencer talks MIDI, and the program running on the computer is receiving MIDI note data from the sequencer, and shows the notes being played in real-time. It works the other way around, too - stop the sequencer, and notes can be sent from the computer to the sequencer, thus driving the oscillator.
Nerdy sound generator stuff đ
Inside the red box is what is actually making the sound - a home-brewed oscillator, being prototyped on a "breadboard."  It accepts control voltages that determine what frequency of sound to output.  An increase of 1 volt shifts everything up by 1 octave.  
The green box is a sequencer.  It sends control voltages, configurable per step, to the oscillator.
Blue box is a bench power supply - crude for this purpose, but easy to use for testing.  It is spitting out both + and - 12VDC.
Orange box is a bench multimeter, connected to monitor the + voltage output. 
Purple is the oscilloscope, monitoring the audio spit out by the oscillator. 
And bonus: that sequencer talks MIDI, and the program running on the computer is receiving MIDI note data from the sequencer, and shows the notes being played in real-time.  It works the other way around, too - stop the sequencer, and notes can be sent from the computer to the sequencer, thus driving the oscillator.