Power Supply Unit (PSU)

The power supply unit (PSU) converts low voltage (commonly between 2 and 12V, depending on the unit) into the high voltage required by the tube (up to 60 kV for cascade designs). Most PSUs are a two stage design with a lower voltage part (often 2kv) with all the control logic in one stage and the high voltage stage which creates the necessary voltage for the phosphor screen. With older designs each stage is often a seperate component.

The logic inside the first stage is responsible for functions like automatic brightness control, bright source protection or autogating.