"whisky-dave" wrote in message
...

Dimmable fluorescent fittings have been around since the early 1960s.
Nothing new there.

How are fluorescents dimmed? I'd always thought that it was impossible, and
was surprised when the fluorescents in my school lecture theatre could be
dimmed. They were probably installed in the early to mid 70s, which gives an
idea of what technology was available then. I remember a huge cabinet about
the size of a 6-foot high freezer in the projection unit which gave off a
hell of a hum as the lights were going from full off to full on, which they
did on a timer: the lecturer pressed a button and they dimmed/brightened
automatically over the course of about 5 seconds.