Relaxation Oscillations in Voltage-Regulator Tubes

Gas-filled voltage-regulator tubes are subject to relaxation oscillations when operated in parallel with a condenser. These oscillations have been investigated and a qualitative description of their mechanism is presented. It was found that the voltage across the tube as a function of current has a minimum, and that if the current through the tube is greater than that at the voltage minimum, then relaxation oscillations do not occur. It was also found that a 100-ohm resistance in series with a VR105 tube reduces the tube current required to prevent oscillations.