The period of oscillation can be calculated from the breakdown and extinction voltage thresholds of the lamp used.

The breakdown and extinction voltages of neon lamps may vary between similar parts; manufacturers usually specify only wide ranges for these parameters.

The extinction voltage is usually considerably lower than the strike voltage, i.e., the arc is difficult to get going, and then difficult to stop once started.

The bulb will continue to conduct current until the applied voltage drops below the extinction voltage V (point d), which is usually close to the maintaining voltage.

When the voltage drops to the extinction voltage V of the bulb (d), the bulb turns off and the current through it drops to a low level (a).

The circuit thus functions as a low-frequency relaxation oscillator, the capacitor voltage oscillating between the breakdown and extinction voltages of the bulb in a sawtooth wave.

Afterglow occurs in glass or silica tubes when the inverter has sufficient power to keep the capacitors charged to a point above the tube extinction voltage while the gas is conducting.