In article , Eeyore wrote:


GregS wrote:

Eeyore wrote:
GregS wrote:
Eeyore wrote:
Arfa Daily wrote:

With a bit of work, I'm sure that they [LEDs] will
also get to the point where they can replace a standard filament bulb,
in
the same sized package, unlike a CFL which has to accommodate the
ballast.

To run LEDs efficiently from 240V AC will also require some active
electronics.
I see no-one ever factors in the power losses that'll be associated with
that.

When you use up the watts, you get heat. The lamp has to efficiently get
rid of it. May even need a fan.

Quite possibly so. How many watts does the fan need ?

I have one here that's 40mm sq. It still uses 1W.


I'm actually using a CPU sink/fan combo, but the LED's are epoxied to a
copper
plate. I even have diamond dust as a buffer/insulator. To close space the
LED's
I needed the best thermal transfer. Did I forget to mention the Peltier
device.
I am also using unmounted LED's.


In my experimental 45 watt, 9- 5 watt Luxeon array, I use copper,
aluminum,
and a fan. DC drive is nice.

The normal home doesn't have DC. What do you use for current limiting and
how
much power does that dissipate ?

Nothing is compact. I use a large variable supply.

And the efficiency of that is ?


There is 45 watts going to the LED's.
About 20 amps. 3 series sets of LED's. You cannot look at the
light.
The device was intended to be flashed in the final form. peaking at about 60
watts.

So how do you control the LED current ? I imagine you may have current sharing
issues with parallel chains
too.

What's the AC input watts ?

Not sure, but I am not concerned with efficiency. I am concerned with heat dissapation.
With same batches I have. the individual specs are very close together, so
load distribution is no problem at all. I use a variable voltage/current supply. I
just have to watch to easily move the controls. This is just a test hookup
for now. I am using blue and green colors, they will be strobed to get effects.

A few months ago I bought a batch of cool white 3 watters. I intended to put
some around the house and control them with X10. It
got too complicated with the X10, and I didn't really like the cool white.
The blue LED's are really neat. I have never seen that mystical color temperature
out of LED's before.