"William Gothberg" "William wrote in message
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On Thu, 20 Dec 2018 22:22:41 -0000, Rod Speed
wrote:



"William Gothberg" "William wrote in message
news
On Thu, 20 Dec 2018 21:50:21 -0000, Rod Speed
wrote:



"William Gothberg" "William wrote in message
news On Thu, 20 Dec 2018 21:04:01 -0000, Rod Speed

wrote:



"William Gothberg" "William wrote in
message
news On Thu, 20 Dec 2018 17:13:52 -0000, trader_4
wrote:

On Thursday, December 20, 2018 at 12:07:40 PM UTC-5, William
Gothberg
wrote:
On Thu, 20 Dec 2018 16:25:22 -0000, trader_4

wrote:

On Thursday, December 20, 2018 at 7:29:53 AM UTC-5, William
Gothberg
wrote:
On Thu, 20 Dec 2018 11:57:01 -0000, whisky-dave
wrote:

On Wednesday, 19 December 2018 16:35:05 UTC, William Gothberg
wrote:
On Wed, 19 Dec 2018 16:21:41 -0000, Mark Lloyd

wrote:

On 12/19/18 6:01 AM, William Gothberg wrote:

[snip]

They probably are fairly crude. I know they flicker, for
example if I
use my cordless drill, the chuck appears to spin the
wrong
way
under the
LED lighting.
I remember seeing that with a washing machine (under
fluorescent
lights). As the tub was slowing down, the row of holes
around
the tub
would appear to reverse direction. Same thing with
(spoked)
wagon wheels
in movies.

It looks absolutely ridiculous with modern cars with LED
headlights in films. How hard can it be to put a smoothing
capacitor on the output of the power supply?

It's easy but that isn't the point. The most efficient way of
driving to make maximium power into the LED means yuo have
to
pulse the LED's. Using a capcitor to smooth out the DC is yet
another mode of inefficincy as it would get warm due to
current
flow. Indictors in series might be better but then you run
the
risk
of 'radio' interference.

Being inefficient would presumably make it impossible to get
enough
brightness out of LEDs that fit into the lamp holder. The LEDs
would
get too hot trying to give out enough brightness for a car
headlight.

However cars vary a lot, some are easy to detect flickering,
some
difficult, and some impossible (with the naked eye). Perhaps
they
just use a higher frequency?

Taillights are pretty bad on a lot of cars, as they dim the
brakelights by deliberately flickering them.

Either you have eyes that are way more sensitive to this or
you're
in
a
country that uses different car lights than here in the USA.
There
are a lot of cars with LED lighting, headlights and rear lights,
and
I've never noticed this flickering, nor have I ever heard it
mentioned
before this thread. I haven't noticed flickering from any LED
lights
I've used either.

I can see flicker on a 60Hz CRT monitor, but not on a 90Hz one, so
that'll give you an idea on how good my eyes are.

Can you see flicker on tailliights if you scan your eyes across
the
scene?

Like I said, I haven't noticed it in the driving I've done. Nor
have
I
heard anyone else mention it. Next time I come across a car that
has
LEDs I'll look more closely and see if I can see anything. If just
scanning reveals it, you;d think a lot of people would be noticing
it.
Scanning is a part of driving.

I'd estimate about 1 in 5 people can see it,

Its nothing like that high and we know that because nothing
like that many saw any flickering with fluorescent lights.

Er.... most people I know can see fluorescent flicker. It doesn't
annoy
most of them, but they can detect it.

Don't believe it. I did have someone at work who could
see it and was asking about how to get it fixed but no
one else could see what she was talking about.

About 20 years ago I worked where everyone had a cheap 14" CRT monitor
running at 60Hz. They really bugged me with the flicker. When I asked
everyone about them, 80% couldn't see it, 10% said they were as annoyed
as
me, and 10% only saw it if they looked for it. For the 10% and the 10%,
I
bought some nice 90Hz Iiyama Vision Master Pro CRT monitors. They
absolutely loved them. The other 80% couldn't see what the fuss was
about, and most of them had specs or were older.

One in five people I know could see 60Hz monitor flickering.

Don't believe that either and I never had anyone complaining about it.

And about the same can see car lights flickering.

Don't believe that either and clearly the designers can't.

A quick google search shows many many people don't like car flicker.
Millions of results.

similar to how many can see flicker on a 60Hz CRT computer monitor.

Nothing even remotely like 1 in 5 can see that.

You must know some people with really ****ty eyesight.

I'm talking about everyone at work. NOT ONE could see that.

What age group were they in?

All of the, everything from those straight out
of school to those who were about to retire.
And the kids of many of them as well.

How odd. I can't believe Aussies have different eyes to Brits.

Yeah, I don't believe that either.

More sunlight in the room maybe?

That's certainly true of my main room but only in the daytime.

Having 90Hz CRTs to avoid flicker was quite common around the world, go
google it.

Don't need to, I know that but never saw the need for them.
OTOH I was using decent quality DEC VT100s, maybe the
phosphor was better chosen and that's why it wasn't a problem.

I noticed that more people who were younger and/or didn't wear specs
could see the flicker.

Don't buy that either. None of the kids could see it.

Even a colleague who never noticed it before when he looked at one of
the
new 90Hz monitors immediately remarked "that picture's really stable!"

Don't most cars have LEDs now? Or does your area have a lot of
older
cars? People (stupidly) around here seem to like cars that are no
more
than 10 years old. I don't think many cars after 2008 had bulbs.

Searching for "LED tail light flicker" without the quotes in google
produces 4.5 million results!