Ballast regulates voltage and a transformer merely increases or decreases voltage. A ballast will send a short high voltage pulse (600-50k volts, depending on application) to strike an arc and regulate the voltage to keep the arc going. (I'm a light freak! )

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1999 navy blue SE
Zetec ATX
PIAA headlamp/foglamp bulbs
Hella Optilux 1100 foglamps
Sidemarkers
No performance mods, yet.

P. Valdez

1998 VW Jetta TDI
1.9L I4 direct injection turbo diesel
5 speed manual
no mods, no money

AIM:PackRatTDI

My exhaust smells better than yours.