This high-voltage coil can be used with Crookes’ tubes, cathode ray tubes, or Canal ray tubes.
A regulator allows the tubes to be started at minimum voltage and turned up until the desired effect is obtained. The variable pulsating spark ranges from 1/2" to 2". It is current limited to protect the tube connected to it. The binding posts are clearly marked (polarity switch, voltage control, on/off, and pilot light), and the unit is maintenance free.