In sci.electronics.repair Arfa Daily wrote:


"Cydrome Leader" wrote in message
...
In sci.electronics.repair Arfa Daily wrote:
Has anyone seen any good write-ups on, or figured out for themselves,
just
how the self-oscillating dirty - i.e. smoothing cap-less - switchers
that
you find in use as lamp ballasts (or 'electronic transformers' that they
seem to be sometimes known as) work ?

I recently acquired a fairly sophisticated disco lighting fixture that
has
such a supply to run the 24v 150 watt lamp. It seems to have two main
switching devices, which I suspect are FETs or IGBTs, but can't tell for
sure so far, as the numbers have been ground off them. On the mains
side,

That's pretty high tech for a product from the 1970s to use a switching
power supply.



1970s ? Where did you get that from ? It's actually about 4 or 5 years old
at a guess ...

Arfa

This one seemed to go over everyone's heads.

the joke (and sad truth) is disco never died in europe. All horrible
things last forever there.

the germans have some of the creapiest musicans that are still alive and
popular, like Fancy.