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William Gothberg
Guest

Tue Dec 25, 2018 11:45 pm   



On Tue, 25 Dec 2018 21:55:16 -0000, Rod Speed <rod.speed.aaa_at_gmail.com> wrote:

Quote:


"William Gothberg" <"William Gothberg"@internet.co.is> wrote in message
news:op.zulktmp2o5piw3_at_desktop-ga2mpl8.lan...
On Tue, 25 Dec 2018 21:00:53 -0000, Rod Speed <rod.speed.aaa_at_gmail.com
wrote:



"William Gothberg" <"William Gothberg"@internet.co.is> wrote in message
news:op.zulf8qz8o5piw3_at_desktop-ga2mpl8.lan...
On Tue, 25 Dec 2018 18:33:27 -0000, Rod Speed <rod.speed.aaa_at_gmail.com
wrote:



"William Gothberg" <"William Gothberg"@internet.co.is> wrote in message
news:op.zulb102po5piw3_at_desktop-ga2mpl8.lan...
On Tue, 25 Dec 2018 17:33:52 -0000, Rod Speed
rod.speed.aaa_at_gmail.com
wrote:



"William Gothberg" <"William Gothberg"@internet.co.is> wrote in
message
news:op.zukr2cpgo5piw3_at_desktop-ga2mpl8.lan...
On Thu, 20 Dec 2018 04:22:39 -0000, Clare Snyder
clare_at_snyder.on.ca
wrote:

On Wed, 19 Dec 2018 19:36:51 -0000, "William Gothberg" <"William
Gothberg"@internet.co.is> wrote:

On Wed, 19 Dec 2018 17:47:17 -0000, trader_4
trader4_at_optonline.net
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
not_at_mail.invalid
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.

Bullshit.

Tell me, out of interest, when you watch TV at the usual (before HD) 25fps
interlaced, can you see that it's made up of seperate images?

Meaningless question.


It would show us whether our eyes are inferior or not.

Quote:
Can you notice that a moving object jumps a few inches at a time across
the screen?

Never seen that happen.


Then your eyesight really sux. I guess you don't bother with HD TV. I guess if you play computer games you don't care if the CPU is slow and the frame rate is abysmal.

%
Guest

Tue Dec 25, 2018 11:45 pm   



On 2018-12-25 3:09 p.m., William Gothberg wrote:
Quote:
On Tue, 25 Dec 2018 21:51:13 -0000, % <persent_at_gmail.com> wrote:

On 2018-12-25 2:33 p.m., William Gothberg wrote:
On Tue, 25 Dec 2018 21:00:53 -0000, Rod Speed <rod.speed.aaa_at_gmail.com
wrote:



"William Gothberg" <"William Gothberg"@internet.co.is> wrote in message
news:op.zulf8qz8o5piw3_at_desktop-ga2mpl8.lan...
On Tue, 25 Dec 2018 18:33:27 -0000, Rod Speed
rod.speed.aaa_at_gmail.com
wrote:



"William Gothberg" <"William Gothberg"@internet.co.is> wrote in
message
news:op.zulb102po5piw3_at_desktop-ga2mpl8.lan...
On Tue, 25 Dec 2018 17:33:52 -0000, Rod Speed
rod.speed.aaa_at_gmail.com
wrote:



"William Gothberg" <"William Gothberg"@internet.co.is> wrote in
message
news:op.zukr2cpgo5piw3_at_desktop-ga2mpl8.lan...
On Thu, 20 Dec 2018 04:22:39 -0000, Clare Snyder
clare_at_snyder.on.ca
wrote:

On Wed, 19 Dec 2018 19:36:51 -0000, "William Gothberg" <"William
Gothberg"@internet.co.is> wrote:

On Wed, 19 Dec 2018 17:47:17 -0000, trader_4
trader4_at_optonline.net
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
not_at_mail.invalid
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.

Bullshit.

Tell me, out of interest, when you watch TV at the usual (before HD)
25fps interlaced, can you see that it's made up of seperate images?  Can
you notice that a moving object jumps a few inches at a time across the
screen?


if the dope is good enough

Don't need dope to see the TV for what it really is.  A series of still
images intended to fool those with slow eyesight.  That's why HD has
progressive encoding, doubling the frame rate.


i like when you show your sense of humor

William Gothberg
Guest

Wed Dec 26, 2018 12:45 am   



On Tue, 25 Dec 2018 22:21:27 -0000, % <persent_at_gmail.com> wrote:

Quote:
On 2018-12-25 3:09 p.m., William Gothberg wrote:
On Tue, 25 Dec 2018 21:51:13 -0000, % <persent_at_gmail.com> wrote:

On 2018-12-25 2:33 p.m., William Gothberg wrote:
On Tue, 25 Dec 2018 21:00:53 -0000, Rod Speed <rod.speed.aaa_at_gmail.com
wrote:



"William Gothberg" <"William Gothberg"@internet.co.is> wrote in message
news:op.zulf8qz8o5piw3_at_desktop-ga2mpl8.lan...
On Tue, 25 Dec 2018 18:33:27 -0000, Rod Speed
rod.speed.aaa_at_gmail.com
wrote:



"William Gothberg" <"William Gothberg"@internet.co.is> wrote in
message
news:op.zulb102po5piw3_at_desktop-ga2mpl8.lan...
On Tue, 25 Dec 2018 17:33:52 -0000, Rod Speed
rod.speed.aaa_at_gmail.com
wrote:



"William Gothberg" <"William Gothberg"@internet.co.is> wrote in
message
news:op.zukr2cpgo5piw3_at_desktop-ga2mpl8.lan...
On Thu, 20 Dec 2018 04:22:39 -0000, Clare Snyder
clare_at_snyder.on.ca
wrote:

On Wed, 19 Dec 2018 19:36:51 -0000, "William Gothberg" <"William
Gothberg"@internet.co.is> wrote:

On Wed, 19 Dec 2018 17:47:17 -0000, trader_4
trader4_at_optonline.net
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
not_at_mail.invalid
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.

Bullshit.

Tell me, out of interest, when you watch TV at the usual (before HD)
25fps interlaced, can you see that it's made up of seperate images? Can
you notice that a moving object jumps a few inches at a time across the
screen?


if the dope is good enough

Don't need dope to see the TV for what it really is. A series of still
images intended to fool those with slow eyesight. That's why HD has
progressive encoding, doubling the frame rate.

i like when you show your sense of humor


It's spelt humour.

And I wasn't being funny, I was stating a fact - SD TV is shit.

Rod Speed
Guest

Wed Dec 26, 2018 12:45 am   



"William Gothberg" <"William Gothberg"@internet.co.is> wrote in message
news:op.zulmf92mo5piw3_at_desktop-ga2mpl8.lan...
Quote:
On Tue, 25 Dec 2018 21:00:53 -0000, Rod Speed <rod.speed.aaa_at_gmail.com
wrote:



"William Gothberg" <"William Gothberg"@internet.co.is> wrote in message
news:op.zulf8qz8o5piw3_at_desktop-ga2mpl8.lan...
On Tue, 25 Dec 2018 18:33:27 -0000, Rod Speed <rod.speed.aaa_at_gmail.com
wrote:



"William Gothberg" <"William Gothberg"@internet.co.is> wrote in message
news:op.zulb102po5piw3_at_desktop-ga2mpl8.lan...
On Tue, 25 Dec 2018 17:33:52 -0000, Rod Speed
rod.speed.aaa_at_gmail.com
wrote:



"William Gothberg" <"William Gothberg"@internet.co.is> wrote in
message
news:op.zukr2cpgo5piw3_at_desktop-ga2mpl8.lan...
On Thu, 20 Dec 2018 04:22:39 -0000, Clare Snyder
clare_at_snyder.on.ca
wrote:

On Wed, 19 Dec 2018 19:36:51 -0000, "William Gothberg" <"William
Gothberg"@internet.co.is> wrote:

On Wed, 19 Dec 2018 17:47:17 -0000, trader_4
trader4_at_optonline.net
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
not_at_mail.invalid
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.

Bullshit.

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.


Only to freaks. And even you should have noticed
that the regulatory authoritys have not proscribed
car lights that can be seen to flicker by freaks.

Quote:
Even a fuckwit like yourself should realise that's a bad thing for
everyone.


Even a terminal fuckwit should have noticed that
the regulatory authoritys have not proscribed
car lights that can be seen to flicker by freaks.

Quote:
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.


Nothing wrong the negatives in that sentence.

Quote:
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.


What you freaks whine about, actually.

Quote:
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?!


Not lost, just cant remember where it ended
up and can't be bothered looking for it.

Quote:
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.


Corse it is with that stupid every single car claim.

My current car, which has incandescent
headlights doesn't have that.

Quote:
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.


Wrong, as always.

> There is an optimum brightness, above which you dazzle other drivers,

Not possible with high beam, stupid.

> and below which you cannot see as well.

Even sillier than you usually manage,
and that's saying something.

It isnt just the wattage that matters, its also
the beam shape with dipped headlights.

Quote:
which requires about 5.5W of LEDs.

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

Then state what the real story is.


There is no nice tidy number like that. Depends
on the beam with dipped lights and the more
the better with high beam lights within reason.
That's why plenty add driving lights.

Quote:
Easy to arrange that with reflectors and cooling without pulsing.

Yeah, yeah, none of the designed of car headlights
have a fucking 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.


Stupid way for those to do it. Makes a lot more
sense to do it the way those that did it right
did if if you do want to pander to freaks.

Rod Speed
Guest

Wed Dec 26, 2018 12:45 am   



"William Gothberg" <"William Gothberg"@internet.co.is> wrote in message
news:op.zulmjwcgo5piw3_at_desktop-ga2mpl8.lan...
Quote:
On Tue, 25 Dec 2018 21:55:16 -0000, Rod Speed <rod.speed.aaa_at_gmail.com
wrote:



"William Gothberg" <"William Gothberg"@internet.co.is> wrote in message
news:op.zulktmp2o5piw3_at_desktop-ga2mpl8.lan...
On Tue, 25 Dec 2018 21:00:53 -0000, Rod Speed <rod.speed.aaa_at_gmail.com
wrote:



"William Gothberg" <"William Gothberg"@internet.co.is> wrote in message
news:op.zulf8qz8o5piw3_at_desktop-ga2mpl8.lan...
On Tue, 25 Dec 2018 18:33:27 -0000, Rod Speed
rod.speed.aaa_at_gmail.com
wrote:



"William Gothberg" <"William Gothberg"@internet.co.is> wrote in
message
news:op.zulb102po5piw3_at_desktop-ga2mpl8.lan...
On Tue, 25 Dec 2018 17:33:52 -0000, Rod Speed
rod.speed.aaa_at_gmail.com
wrote:



"William Gothberg" <"William Gothberg"@internet.co.is> wrote in
message
news:op.zukr2cpgo5piw3_at_desktop-ga2mpl8.lan...
On Thu, 20 Dec 2018 04:22:39 -0000, Clare Snyder
clare_at_snyder.on.ca
wrote:

On Wed, 19 Dec 2018 19:36:51 -0000, "William Gothberg" <"William
Gothberg"@internet.co.is> wrote:

On Wed, 19 Dec 2018 17:47:17 -0000, trader_4
trader4_at_optonline.net
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
not_at_mail.invalid
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.

Bullshit.

Tell me, out of interest, when you watch TV at the usual (before HD)
25fps
interlaced, can you see that it's made up of seperate images?

Meaningless question.

It would show us whether our eyes are inferior or not.


Only if it was actually a viable question.

Quote:
Can you notice that a moving object jumps a few inches at a time across
the screen?

Never seen that happen.

Then your eyesight really sux.


Nope, those doing the movie have enough of
a clue to film it properly so that doesn't happen.

> I guess you don't bother with HD TV.

Guess again.

Quote:
I guess if you play computer games you don't care if the CPU is slow and
the frame rate is abysmal.


The only computer game I bother with is Freecell Pro and it
works fine with any cpu and the frame rate is never a problem.

William Gothberg
Guest

Wed Dec 26, 2018 11:45 pm   



On Thu, 20 Dec 2018 03:54:10 -0000, Clare Snyder <clare_at_snyder.on.ca> wrote:

Quote:
On Wed, 19 Dec 2018 11:23:00 -0000, "William Gothberg" <"William
Gothberg"@internet.co.is> wrote:

Do switch mode power supplies flicker in time with mains? Specifically LED power supplies in commercially available domestic lamps. By in time, I don't mean at the same 50/60Hz, but anchored to it. I.e. if you have several such lamps each with their own built in supply, will they all flicker in time, using the mains frequency to keep them in time, or will they be random, making the room overall not flicker due to them all being random? And is there any way I can test this? I tried taking photos of them, but my camera only goes as fast as 1/2000th of a second, which shows all the lights at the same brightness each time, I suspect the flicker is above 2000Hz.
Leds (at least white ones) on a switch mode supply will not flicker
because the persistance of the phosphor is longer than the period of
the switching frequency which is more than 100kHz - typically 2 mhz.
The answer to the second part of the question is no, the switching is
not syncronized to the mains frequency on MOST switch mode power
supplies.


I'm definitely getting 100Hz flicker from it, I timed it using a slow camera shot (1/10th of a second) while moving the LED across the camera's field of vision. There were exactly 10 bright spots, although they were only 8% brighter than the dim spots. The LEDs don't go off completely. It's enough of a flicker for me to see with my eyes if I scan past the light, and I can detect anomalies when watching something rotating, like a drill chuck. I've got an oscilloscope on order, then I'll be able to check the signal to the LEDs (and in other parts of the supply) accurately.

Daniel60
Guest

Mon Dec 31, 2018 1:45 pm   



William Gothberg wrote on 20/12/2018 11:34 PM:
Quote:
On Thu, 20 Dec 2018 07:09:59 -0000, Daniel60
daniel47_at_eternal-september.org> wrote:

Mark Lloyd wrote on 20/12/2018 3:21 AM:
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.
... and, in real life, the Mag wheels of some cars seem to be spinning
backwards, dependant on the speed at which the car is travelling!!

In real life?  I assume you mean under streetlighting.  That effect
can't occur with a steady lightsource such as the sun.


No, I'm sure I've noticed it in sunlight, as well.

And my 'real life' was to distinguish from the mentioned "wagon wheels
in movies"!
--
Daniel

NY
Guest

Mon Dec 31, 2018 4:45 pm   



"Daniel60" <daniel47_at_eternal-september.org> wrote in message
news:q0d2fs$vof$1_at_dont-email.me...
Quote:
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.
... and, in real life, the Mag wheels of some cars seem to be spinning
backwards, dependant on the speed at which the car is travelling!!


That's not what I'd call flicker, which is when an object is illuminated
sufficiently infrequently that you can see each pulse of light, even when
there's no motion in the scene. CRT TVs, especially European 625/25 as
opposed to US 525/30, were prone to flicker, especially if you saw one out
of the corner of your eye which seems to be more sensitive to flicker. CRT
computer monitors on 50 Hz progressive flicker more than on 60 Hz, and 72 or
90 Hz are better still. Interlaced scans are smoother for the same refresh
rate, but suffer from "twitter" where alternate lines flicker even though
the picture as a whole looks constant.

What you are describing is a stroboscopic effect of viewing a moving
contrasty object by intermittent light. That can happen at any intermittent
rate, even those which are far faster than the eye perceive as flicker. If
you let your eyes pan across an LED, you will see several images of it for a
fraction of a second - it's noticeable with some car rear lights or some
traffic lights, if there is relative motion (you are driving past the car or
traffic light).

Quote:
In real life? I assume you mean under streetlighting. That effect can't
occur with a steady lightsource such as the sun.

No, I'm sure I've noticed it in sunlight, as well.


If you are seeing stroboscopic effects under DC light or sunlight, which are
constant not intermittent light level, then there's something very odd going
on.

Quote:
And my 'real life' was to distinguish from the mentioned "wagon wheels in
movies"!


My dad's old record player had two sets of black and white stripes round the
edge of the turntable, so you could set the correct speed stroboscopically
under 50 Hz or 60 Hz mains light. What was surprising was that it worked
even with filament lights which have a long thermal inertia, so the light
doesn't change instantly from on to off, as with a LED or fluorescent tube
(*), but decays gradually. Despite this, the stripes were still fairly sharp
and not blurred. Of course, any setting of the turntable speed is only as
accurate as the mains frequency at the time, which can vary by up to +/- 0.5
Hz (http://mainsfrequency.uk/fm-home). I think the strobe markings were
calibrated for 33 1/3 rpm, with the assumption that the "gearing" (sprockets
or friction wheels) for the other speeds was exact, so if you calibrated at
one speed, it would be correct by definition at the other speeds.



(*) OK, with a fluorescent you see two images: a bluish one caused by the
very rapid on-to-off transition of the mercury discharge and a yellowish one
caused by the more gradual decay of the phosphor, though this decay is still
a lot quicker than the light from a filament bulb.

The Natural Philosopher
Guest

Mon Dec 31, 2018 4:45 pm   



On 31/12/2018 15:01, NY wrote:
Quote:
If you are seeing stroboscopic effects under DC light or sunlight, which
are constant not intermittent light level, then there's something very
odd going on.


something ELSE going on.

leaves in the breeze casting dappled shade...

in a moving car running past an avenue of trees...


--
I would rather have questions that cannot be answered...
....than to have answers that cannot be questioned

Richard Feynman

NY
Guest

Mon Dec 31, 2018 5:45 pm   



"The Natural Philosopher" <tnp_at_invalid.invalid> wrote in message
news:q0dbrc$ndc$2_at_dont-email.me...
Quote:
On 31/12/2018 15:01, NY wrote:
If you are seeing stroboscopic effects under DC light or sunlight, which
are constant not intermittent light level, then there's something very
odd going on.

something ELSE going on.

leaves in the breeze casting dappled shade...

in a moving car running past an avenue of trees...


True, although I was assuming that the OP really did mean constant sunlight,
not sunlight modified by periodic variations due to shadows.

Even in bright sunlight I'm sure I could easily "freeze" a rotating object
if it was illuminated by direct sunlight coming through the spinning blades
of a desk fan :-)



The stroboscopic freezing of spinning objects can be very serious. My
grandpa was a model engineer in his spare time and he had a lathe. The room
was illuminated by fluorescent tubes, but he made sure that the light which
he shone on the work used a tungsten bulb with a nice long time constant to
avoid the chuck appearing to be stationary or slow-moving even though it was
spinning fast, so he didn't instinctively touch the tool to change it,
thinking that it had stopped. I wonder what precautions are used nowadays
with the increased use of (pulsed) LED lights. Maybe two banks of LEDs which
are 180 degrees out of phase so the light level is constant even though all
the LEDs are flashing quickly with a variable mark-space ratio to control
the required brightness. Or else maybe a random element added to the
flashing rate.

I have an LED desk lamp and the coarse brightness control is by switching on
one or both banks of LEDs (fine adjustment is by variable M:S ratio), and
with only one bank lit there is a lot more strobing (*) than with both
banks, so I bet the two banks are out of phase.

(*) For example if you move your finger rapidly from side to side.

William Gothberg
Guest

Mon Dec 31, 2018 10:45 pm   



On Mon, 31 Dec 2018 12:36:09 -0000, Daniel60 <daniel47_at_eternal-september.org> wrote:

Quote:
William Gothberg wrote on 20/12/2018 11:34 PM:
On Thu, 20 Dec 2018 07:09:59 -0000, Daniel60
daniel47_at_eternal-september.org> wrote:

Mark Lloyd wrote on 20/12/2018 3:21 AM:
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.
... and, in real life, the Mag wheels of some cars seem to be spinning
backwards, dependant on the speed at which the car is travelling!!

In real life? I assume you mean under streetlighting. That effect
can't occur with a steady lightsource such as the sun.

No, I'm sure I've noticed it in sunlight, as well.

And my 'real life' was to distinguish from the mentioned "wagon wheels
in movies"!


There is no way you could observe reverse rotation with the naked eye and a constant light source such as the sun. You need a light source that illuminates intermittently, the timing so that the spokes have moved quite a distance, so you assume they moved backwards.

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