On Sat, 05 Oct 2019 22:15:34 +0100, AlexK wrote:



"Commander Kinsey" wrote in message
news
On Sat, 05 Oct 2019 21:17:00 +0100, AlexK wrote:



"Commander Kinsey" wrote in message
news On Fri, 04 Oct 2019 23:46:55 +0100, AlexK wrote:



"Commander Kinsey" wrote in message
news On Fri, 04 Oct 2019 19:17:46 +0100, AlexK wrote:



"Commander Kinsey" wrote in message
news On Fri, 04 Oct 2019 09:41:25 +0100, PeterC

wrote:

On Thu, 3 Oct 2019 19:29:42 +0100, Robert wrote:

On 03/10/2019 14:29, Commander Kinsey wrote:
Why do LEDs generate heat? I want a technical answer not "because
they're inefficient". And will we ever make them more efficient?
Besides the inefficiencies in the LED itself which other posters
have
covered, LED lamps have some current regulation or power supply
built-in
which will not be 100% efficient and thus generates heat.

If my meter is correct, all the LEDs that I've measured have a PF
of
approx.
0.5 - not a good start.
One TV has a PF of 0.97 and is barely warm over the PSU; another is
0.86
and
is luke warm. The real warmth in the 2nd. one is around the inputs
though -
SPDIF, USB and HDMI.

Is power factor that important? In a domestic building, you are not
billed for power factor. I might have a capacitive load, but my
neighbour
has an inductive load, so they even out.

Most neighbours don't have much long term inductive load anymore.

I don't see why it would have reduced.

It has anyway.

For what reason

To get better motors, direct drive etc with washing machines for example.

What has direct drive got to do with power factor?

They arent the old induction motors with the power factor they had.

I thought all motors created the same inductive load, and had to be compensated for if you wanted unity PF.

Direct drive motors are interesting - I once had a very cheap turntable
that said "direct drive", so I guess it's not always a good thing?

There's a big difference between a turntable motor and
one in a top loading washing machine which needs to
do a variety of different things when washing, adjitating
and spin drying at different speeds.

I know. Which makes me think it's important for a washing machine. But on a turntable, it has to be a very precise speed or the music sounds ****. It's the last place I'd think of putting one.

Actually I think I remembered wrong, the cheap stereo might have said "belt drive" on the front. Direct drive could have been the decent one.

From Wikipedia: "Usually motors are built to achieve maximum torque at
high rotational speeds, usually 1500 or 3000 rpm."
I thought motors produced more torque when slower - which is why they burn
out when jammed.

Not relevant to what is being discussed, the power factor.

Aren't I allowed to drift the conversation a little?