I was reading the Gas Discharge Tube page http://www.allaboutcircuits.com/vol_3/chpt_7/2.html where it says:
I breadboarded up one of these oscillators long ago. It stayed in tune and sounded cool. Frequency control and sine waves aren't everything.
Analog music synthesizers have been using relaxation oscillator VCOs built with solid-state components since at least the 1960s. The frequency control is excellent, and the resulting sawtooth wave sounds nice, is rich in harmonics, and serves as the basis for deriving other standard musical waves (square, pulse, triangle, sine).
About ten or twelve years ago, tube guru Eric Barbour made a synthesizer VCO using a 2D21 thyratron. Variants of this oscillator appear in his commercial MIDI-controlled Phattytron (http://www.keyboardmuseum.com/ar/m/meta/pt1.html) and in his TM-3 Gas-Tube Dual VCO with Suboctave, available to this day from Metasonix (http://www.metasonix.com/index.php?option=com_content&task=view&id=14&Itemid=31).Although I'm not sure if this was ever done, someone could have applied the thyratron tube to a relaxation oscillator circuit and control the frequency with a small DC voltage between grid and cathode, making a crude voltage-controlled oscillator, otherwise known as a VCO. Relaxation oscillators tend to have poor frequency control, not to mention a very non-sinusoidal output, and so they exist mostly as demonstration circuits (as is the case here) or in applications where precise frequency control isn't important. Consequently, this use of a thyratron tube would not have been a very practical one.
I breadboarded up one of these oscillators long ago. It stayed in tune and sounded cool. Frequency control and sine waves aren't everything.
Analog music synthesizers have been using relaxation oscillator VCOs built with solid-state components since at least the 1960s. The frequency control is excellent, and the resulting sawtooth wave sounds nice, is rich in harmonics, and serves as the basis for deriving other standard musical waves (square, pulse, triangle, sine).