I have a power strip with a neon bulb that I would like to understand better. I can vary the voltage to the power strip by turning off and on an electric heater in the same room. With the heater on the voltage at the power strip reads about 125.0V on a digital volt meter. With the heater off the voltage at the power strip reads about 121.0V . In the "low" voltage state the neon bulb is off and in the "high" voltage state it is on, but the light flickers almost like Morse Code, on about one half the time. I understand that below a certain voltage the bulb won't work. What causes the random like operation when the bulb is on? If the voltage is near threshold is the bulbs light output effected by terrestrial radiation? I just put an 12 inch stack of books above the bulb, when I do the light decreases and the flicker slows down? Am I blocking radiation? Thanks for any ideas or help?