On Tue, 25 Dec 2018 17:33:52 -0000, Rod Speed wrote:



"William Gothberg" "William wrote in message
news
On Thu, 20 Dec 2018 04:22:39 -0000, Clare Snyder
wrote:

On Wed, 19 Dec 2018 19:36:51 -0000, "William Gothberg" "William
wrote:

On Wed, 19 Dec 2018 17:47:17 -0000, trader_4
wrote:

On Wednesday, December 19, 2018 at 11:35:06 AM UTC-5, 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?

I've never noticed that. Any films come to mind?

A lot of Top Gear programs showing the DRLs of cars fitted with LEDs.
With a feature film, they might take the time/trouble/money to do
something to stop it.

It seems especially
weird, since cars have a 12V supply with a big battery to smooth
anything out. I guess the power supply that reduces that to whatever
the LED headlights use though might have a switching power supply these
days too.

AFAIK it's deliberate, making the LEDs operate brighter than they are
capable of, but only 1/4 of the time. Our eyes just see the brightest
part of the cycle, so we think they're four times brighter than the LED
is really capable of, without overheating itself.

That is PWM Overdrive. Peak junction current is over the nominal
rating, but the average power consumption is below nominalmaximum
current - and the peak lumen output is significantly enhanced without
reducing the junction life appreciably.
THIS would definitely cause flicker as there is a "significant" dead
period between the "strobe flashes"

Agreed, although Rod thinks only freaks can see it.

Its true with car lights.

You're obviously wrong, just by the number of articles on the internet about it.

I wonder why none of my houselights use this?

Hues bulbs do, you can see that by waving something non
transparent past a bulb when looking directly at a lighted bulb.

Your strip house lights have far more leds so don't need to.

Do car lights have to make more brightness from a smaller area?

Corse they do.

Or would flickery houselights annoy people more?

They don't with Hue bulbs.

They don't annoy YOU. They probably annoy others.

If it's the extra brightness, I don't understand

As always.

because I have a torch with a single LED and parabolic reflector that
gives out 20W equivalent without overdrive. Simply have three such lamps
with their own little (only 1.5 inches across) reflector next to each
other to make the headlamp.

Even you should have noticed that car headlights are much brighter.

A car headlight SHOULD be 60W equivalent. So 6W of LEDs, or a few of my torches per lamp. Quite possible to just have three reflectors just like my torch, mounted together.