Kevin McMurtrie
Guest
Wed Mar 17, 2010 6:54 am
In article <S_ydnbejoOpJUgbWnZ2dnUVZ8l9i4p2d_at_brightview.co.uk>,
usenet_at_mauve.plus.com (Ian Stirling) wrote:
Quote:
Jim Thompson <To-Email-Use-The-Envelope-Icon_at_my-web-site.com> wrote:
On Fri, 12 Mar 2010 09:50:24 -0600, usenet_at_mauve.plus.com (Ian
Stirling) wrote:
Martin Brown <|||newspam|||@nezumi.demon.co.uk> wrote:
[snip]
When they can do 140lm/W at 5-10W they will be competitive as spotlamp
replacements (a position where CFLs are truly dreadful). Pricing is
still an issue even allowing for the longer lifetime.
It depends.
They are currently just fine for spotlamp replacements.
A 50W halogen will put out ~700lm. You can do this with either:
5 LEDs at ~1.1W, for a total power input of around 6.2W (with a 90%
efficient ballast), or two LEDs at ~11W input.
Guess which is going to come to market first.
[snip]
Will/Do those devices include power-factor correction?
No.
At least not on the level of individual fixtures.
It's quite possible to do, of course - but it means another stage.
(or letting the LEDs flicker, which makes them less efficient.
Flyback regulators can operate off anything from a couple of volts to
hundreds of volts. The power filtering capacitance becomes extremely
small, even in the range of a foil capacitor. You don't get a perfect
power factor out of this but it's drawing power from all but the lowest
few volts of the cycle.
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