Lamps with DALI ballasts are fully dimmable. Fluorescent lamps using conventional magnetic ballasts flicker at twice the supply frequency. Newer fluorescent lights without magnetic ballasts have essentially eliminated flicker. Mercury vapor lamp ballasts are similar to the ballasts used with fluorescent lamps. Inductive ballasts include power factor correction capacitors. All HID headlamps worldwide presently use the standardized AC-operated bulbs and ballasts. Used in high end electronic fluorescent ballasts. These are used in variable fluorescent light ballasts, and power control systems. Simple inductive fluorescent lamp ballasts have a power factor of less than unity. These devices include personal computers and peripheral devices, and electrical ballasts for fluorescent lights. At night, ORNL HSL uses variable-intensity fluorescent lighting electronic control ballasts. In the US, ballasts and fixtures for mercury vapor lamps were banned in 2008. PCB-filled paper capacitors are found in very old (pre-1975) fluorescent lamp ballasts, and other applications. PCB-filled capacitors are found in very old (pre 1975) fluorescent lamp ballasts, and other applications. Electronic ballasts convert supply frequency AC power to variable frequency AC.