View Single Post
  #283   Report Post  
Posted to alt.home.repair,alt.electronics,uk.d-i-y
William Gothberg William Gothberg is offline
external usenet poster
 
Posts: 190
Default Do switch mode power supplies flicker in time with mains?

On Tue, 25 Dec 2018 21:00:53 -0000, Rod Speed wrote:



"William Gothberg" "William wrote in message
news
On Tue, 25 Dec 2018 18:33:27 -0000, Rod Speed
wrote:



"William Gothberg" "William wrote in message
news 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,

We'll see...

just by the number of articles on the internet about it.

That's just the freaks howling about seeing it.


If it were a small number of freaks, there wouldn't so many articles and
studies into it.


Bull****.

It is a large percentage of the population that can see it.


Easy to claim.

Way more than the percentage of vegetarians and disabled,


Easy to claim.

yet they both get catered for.


Because in the case of the disabled, it stops them getting
around. Being a freak that sees some car lights flicker doesn't.


It causes distraction while driving. Even a ****wit like yourself should realise that's a bad thing for everyone.

In the case of vegetarians, pandering to them sees them
buy what you are flogging and avoids them going to
some other place that does pander to their freakishness.


Please at least try to get your negatives right in sentences.

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.

You wont find anyone saying that they annoy them on the net.


Depends just how flickery they are. If the frequency is high enough, they
won't bother anyone.


I meant that you wont be able to find anyone saying
that the Hue bulbs annoy them by flickering on the
net. Philips must have designed them properly.


With a higher frequency above what us superior beings can see.

Can you set something up to test the light output (or the voltage to the
LEDs) with a scope?


Not easily. The scope probes are hiding
and the scope is too, even tho its pretty big.


You lost an entire oscilloscope?!

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.

Wrong, as always.


Back in the days of incandescent lights on cars, every single car had a
55W/60W bulb for it's headlights.


That's a lie too.


Nope.

55W for dip and 60W for full.


So 6W of LEDs, or a few of my torches per lamp.

Your torches are lying about them being 20W equivalents.


Actually the lie says they're 60W. I measured them as 20W. They consume
2W and give out 20W equivalent.


You don't know that last.


I looked up the specs for the LED it uses. I measured the current it consumes.

Quite possible to just have three reflectors just like my torch, mounted
together.


Yes, but that's nothing like what real headlights produce light wise.


A real headlight should produce the same amount of light as a 55W
incandescent,


They don't all produce the same.


They should. There is an optimum brightness, above which you dazzle other drivers, and below which you cannot see as well.

which requires about 5.5W of LEDs.


There you go, mangling the real story, as always.


Then state what the real story is.

Easy to arrange that with reflectors and cooling without pulsing.


Yeah, yeah, none of the designed of car headlights
have a ****ing clue. Some unemployable drunken
druggy chav knows it all. Yeah, right.


No, most car designers did it right, I'm talking about approximately 1 in 5 cars are done wrongly.