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Do switch mode power supplies flicker in time with mains?

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Brian Gaff
Guest

Wed Dec 19, 2018 6:45 pm   



Well the answer as in many things these days is it depends.
Some are very simple and do have a kind of pulsing taken from ripple on the
mains. Others seem to not do this, indeed poking a phototransistor connected
to an amplifier shows many different results. the same seems to go for CFLs
as well.
You would need to know what circuit they were using etc to figure out why.
One particular led in a stood across the road has a 1khz whine when point
the device at it but modulated onto a 100 hz buzz.

I often wonder if there is some jiggery pokery going on to drive leds hard
for split seconds to make them brighter.
Brian

--
----- --
This newsgroup posting comes to you directly from...
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Blind user, so no pictures please
Note this Signature is meaningless.!
"William Gothberg" <"William Gothberg"@internet.co.is> wrote in message
news:op.zt9okmwvo5piw3_at_desktop-ga2mpl8.lan...
Quote:
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.


Snicker
Guest

Wed Dec 19, 2018 6:45 pm   



In article <op.zt928onno5piw3_at_desktop-ga2mpl8.lan>, "William
Gothberg"@internet.co.is says...
Quote:

On Wed, 19 Dec 2018 16:34:11 -0000, whisky-dave <whisky.dave_at_gmail.com> wrote:

On Wednesday, 19 December 2018 16:21:43 UTC, 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.

You can also observe such things using a smartphone that has a high FPS rate for recodring movie.
I can see the labs lights flicker when I film at 240FPS standard 60 and everything seems fine.

Everybody seems to constantly cut corners. Lights should just be on, no flicker at all. Fucking annoying if you have decent eyesight, I can see the flicker from almost everyone's LED tail lights.


Then stop looking at them.

Rod Speed
Guest

Wed Dec 19, 2018 7:45 pm   



"William Gothberg" <"William Gothberg"@internet.co.is> wrote in message
news:op.zt9sk9gco5piw3_at_desktop-ga2mpl8.lan...
Quote:
On Wed, 19 Dec 2018 12:28:04 -0000, Rod Speed <rod.speed.aaa_at_gmail.com
wrote:



"William Gothberg" <"William Gothberg"@internet.co.is> wrote in message
news:op.zt9qc10co5piw3_at_desktop-ga2mpl8.lan...
On Wed, 19 Dec 2018 11:51:35 -0000, Rod Speed <rod.speed.aaa_at_gmail.com
wrote:

William Gothberg <"William Gothberg"@internet.co.is> wrote

Do switch mode power supplies flicker in time with mains?

No.

Specifically LED power supplies in commercially available domestic
lamps.

None of mine flicker at all.

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?

None of mine flicker at all.

And is there any way I can test this?

Yes, Get or make a strobe disk or use
one of the original LP disks that has
a strobe disk on it and see what it looks
like with the lights illuminating it. You'll
get it appearing to freeze when rotating
if the light level is varying in synch with
the mains frequency.

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.

Or they don't flicker at all. No reason why a proper
switched mode power supply needs to have any
AC component at all on its output. The cruder
ones may well do.

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.

But it's nothing like as low as 50Hz. What I want to know is if the
higher frequency they're flickering at is anchored with the rise of the
AC
wave.

No its not.

I.e. will all the LED lights in the room flicker at precisely the same
time, or will they be out of synch (due to tolerances in the circuitry
of
each PSU)

Due to it not being synched with the mains, actually.

I meant if the PSUs were absolutely identical,


They never can be.

Quote:
and all the lights were switched on at the same time (with one
lightswitch), they should remain in synch forever.


Nope, because the frequency at which the PSU works is entirely
determined by the component tolerances when it isnt operating
at 50Hz because it isnt a simple capacitance dropper.

> But since there are tolerances in all the components in the PSUs,

Most of the components in the PSU don't determine the frequency
it operates at.

> they won't stay in time.

They never will without an explicit design that keeps
the frequency in synch with the mains and there is no
point in the extra components to do that, so they don't.

The only exception is very simple capacitance droppers
that operate at mains frequency and the effect you are
getting with the drill chuck proves that yours arent that.

Quote:
and fudge the brightness together.

Its not a fudge, it's the lack of synch.

I didn't mean fudge, I meant smudge.

And you should be able to see that by watching
the chuck as you move the drill between lights.
The rate and direction of rotation should change.

Only if the frequency is different, which I doubt as they are all the same
model.


The frequencys will be slightly different
because of component variation.

> What I need is a way of detecting if they're flashing together.

Like I said, do the drill chuck thing with all the
lights on at night and move the drill between
lights relatively close to the lights.

Clark W. Griswold
Guest

Wed Dec 19, 2018 7:45 pm   



On 12/19/2018 11:36 AM, William Gothberg wrote:
Quote:
On Wed, 19 Dec 2018 16:18:29 -0000, Mark Lloyd <not_at_mail.invalid> wrote:

On 12/19/18 5:23 AM, William Gothberg 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.

I once had an audio amplifier with a solar cell rather than a microphone
for the input transducer. This made it possible to listen to light. The
sun is steady, incandescent lights (AC powered) hum.

That was 40 years ago. Maybe something like that would work today.

The trouble is I want to compare 2kHz+ from one light with 2kHz+ from a neighbouring light and see if they're in sync.


Maybe use a dual trace oscilloscope?

Since this landed in alt.home.repair, I gotta ask.  Do you have single-phase or two-phase?

William Gothberg
Guest

Wed Dec 19, 2018 8:45 pm   



On Wed, 19 Dec 2018 18:33:09 -0000, Rod Speed <rod.speed.aaa_at_gmail.com> wrote:

Quote:


"William Gothberg" <"William Gothberg"@internet.co.is> wrote in message
news:op.zt9sk9gco5piw3_at_desktop-ga2mpl8.lan...
On Wed, 19 Dec 2018 12:28:04 -0000, Rod Speed <rod.speed.aaa_at_gmail.com
wrote:



"William Gothberg" <"William Gothberg"@internet.co.is> wrote in message
news:op.zt9qc10co5piw3_at_desktop-ga2mpl8.lan...
On Wed, 19 Dec 2018 11:51:35 -0000, Rod Speed <rod.speed.aaa_at_gmail.com
wrote:

William Gothberg <"William Gothberg"@internet.co.is> wrote

Do switch mode power supplies flicker in time with mains?

No.

Specifically LED power supplies in commercially available domestic
lamps.

None of mine flicker at all.

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?

None of mine flicker at all.

And is there any way I can test this?

Yes, Get or make a strobe disk or use
one of the original LP disks that has
a strobe disk on it and see what it looks
like with the lights illuminating it. You'll
get it appearing to freeze when rotating
if the light level is varying in synch with
the mains frequency.

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.

Or they don't flicker at all. No reason why a proper
switched mode power supply needs to have any
AC component at all on its output. The cruder
ones may well do.

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.

But it's nothing like as low as 50Hz. What I want to know is if the
higher frequency they're flickering at is anchored with the rise of the
AC
wave.

No its not.

I.e. will all the LED lights in the room flicker at precisely the same
time, or will they be out of synch (due to tolerances in the circuitry
of
each PSU)

Due to it not being synched with the mains, actually.

I meant if the PSUs were absolutely identical,

They never can be.


Yes I know. It was hypothetical.

Quote:
and all the lights were switched on at the same time (with one
lightswitch), they should remain in synch forever.

Nope, because the frequency at which the PSU works is entirely
determined by the component tolerances when it isnt operating
at 50Hz because it isnt a simple capacitance dropper.

But since there are tolerances in all the components in the PSUs,

Most of the components in the PSU don't determine the frequency
it operates at.

they won't stay in time.

They never will without an explicit design that keeps
the frequency in synch with the mains and there is no
point in the extra components to do that, so they don't.


Which is what I thought.

Quote:
The only exception is very simple capacitance droppers
that operate at mains frequency and the effect you are
getting with the drill chuck proves that yours arent that.

and fudge the brightness together.

Its not a fudge, it's the lack of synch.

I didn't mean fudge, I meant smudge.

And you should be able to see that by watching
the chuck as you move the drill between lights.
The rate and direction of rotation should change.

Only if the frequency is different, which I doubt as they are all the same
model.

The frequencys will be slightly different
because of component variation.


I would have thought so, so why is it that in my room with 10 such lights, I still get flicker. Shouldn't they fill in each other's gaps?

Quote:
What I need is a way of detecting if they're flashing together.

Like I said, do the drill chuck thing with all the
lights on at night and move the drill between
lights relatively close to the lights.


Just did that and proved nothing. Clearly I get the same effect under every light, as they'll be pretty similar frequencies. I'm not going to be able to tell the difference between them with something as simple as a drill chuck. Presumably they're something like 1995 Hz, 2001 Hz, 2003 Hz, etc. All I can think of to prove it would be a higher speed camera so I can spot them being on at different times.

William Gothberg
Guest

Wed Dec 19, 2018 8:45 pm   



Yes I know they have very bright pulsed LEDs in car lights so they can get pretend to look brighter than they really are. The average light output is the same, but the peak output is higher, which fools our eyes. Damn annoying if you have decent eyesight and can see the flicker. And also if you try to film it - I see TV programs about cars where the headlights are flashing as they aren't in time with the camera frames.


On Wed, 19 Dec 2018 17:11:20 -0000, Brian Gaff <briang1_at_blueyonder.co.uk> wrote:

Quote:
Well the answer as in many things these days is it depends.
Some are very simple and do have a kind of pulsing taken from ripple on the
mains. Others seem to not do this, indeed poking a phototransistor connected
to an amplifier shows many different results. the same seems to go for CFLs
as well.
You would need to know what circuit they were using etc to figure out why.
One particular led in a stood across the road has a 1khz whine when point
the device at it but modulated onto a 100 hz buzz.

I often wonder if there is some jiggery pokery going on to drive leds hard
for split seconds to make them brighter.
Brian


Peeler
Guest

Wed Dec 19, 2018 8:45 pm   



On Wed, 19 Dec 2018 10:18:29 -0600, Mark Lloyd, another mentally retarded,
troll-feeding, senile Yankietard, blathered:


> I once had an audio amplifier with a solar cell

That's more cells than you have brain cells, troll-feeding senile idiot!

William Gothberg
Guest

Wed Dec 19, 2018 8:45 pm   



On Wed, 19 Dec 2018 18:03:19 -0000, Clark W. Griswold <clark.w.griswold_at_home.com> wrote:

Quote:
On 12/19/2018 11:36 AM, William Gothberg wrote:
On Wed, 19 Dec 2018 16:18:29 -0000, Mark Lloyd <not_at_mail.invalid> wrote:

On 12/19/18 5:23 AM, William Gothberg 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.

I once had an audio amplifier with a solar cell rather than a microphone
for the input transducer. This made it possible to listen to light. The
sun is steady, incandescent lights (AC powered) hum.

That was 40 years ago. Maybe something like that would work today.

The trouble is I want to compare 2kHz+ from one light with 2kHz+ from a neighbouring light and see if they're in sync.

Maybe use a dual trace oscilloscope?


Haven't got one unfortunately.

> Since this landed in alt.home.repair, I gotta ask. Do you have single-phase or two-phase?

Single. I'm in the UK.

Peeler
Guest

Wed Dec 19, 2018 8:45 pm   



On Wed, 19 Dec 2018 13:03:19 -0500, Clark W. Griswold, another brain
damaged, troll-feeding, senile Yankietard, blathered:


Quote:
Maybe use a dual trace oscilloscope?

Since this landed in alt.home.repair, I gotta ask.  Do you have single-phase or two-phase?


He to no brain, that's his problem! All he knows to do is how to bait the
senile Yanks on Usenet with his insipid trolls! Get a clue, Yankietard!

Peeler
Guest

Wed Dec 19, 2018 8:45 pm   



On Wed, 19 Dec 2018 17:11:20 -0000, Brainless & Daft, the notorious,
troll-feeding senile idiot, blathered

> Well the answer as in many things these days is it depends.

The ONLY right answer here is that HE's a dumb sociopathic troll and
attention whore, and YOU are a dumb mentally deficient troll-feeding senile
idiot!

Peeler
Guest

Wed Dec 19, 2018 9:45 pm   



On Thu, 20 Dec 2018 05:33:09 +1100, cantankerous trolling geezer Rot Speed,
the auto-contradicting senile sociopath, blabbered, again:

<FLUSH another 126 lines of the two prize idiots' endless idiotic babble
unread>

--
Another retarded "conversation" between Birdbrain and senile Rot:

Senile Rot: " Did you ever dig a hole to bury your own shit?"

Birdbrain: "I do if there's no flush toilet around."

Senile Rot: "Yeah, I prefer camping like that, off by myself with
no dunnys around and have always buried the shit."

MID: <fv66kaFml0nU2_at_mid.individual.net>

William Gothberg
Guest

Wed Dec 19, 2018 11:45 pm   



On Wed, 19 Dec 2018 21:33:32 -0000, <makolber_at_yahoo.com> wrote:

Quote:
On Wednesday, December 19, 2018 at 11:36:48 AM UTC-5, William Gothberg wrote:
On Wed, 19 Dec 2018 16:18:29 -0000, Mark Lloyd <not_at_mail.invalid> wrote:

On 12/19/18 5:23 AM, William Gothberg 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.

I once had an audio amplifier with a solar cell rather than a microphone
for the input transducer. This made it possible to listen to light. The
sun is steady, incandescent lights (AC powered) hum.

That was 40 years ago. Maybe something like that would work today.

The trouble is I want to compare 2kHz+ from one light with 2kHz+ from a neighbouring light and see if they're in sync.

it is very unlikely that they will be in sync.
mark


Agreed. All I can detect (with my digital camera) is that one brand of LED light I have flickers about 5 times less (not sure if it's smother or faster) than the others. It's also the brand that lasts longer, probably better designed overall.

William Gothberg
Guest

Thu Dec 20, 2018 12:45 am   



On Wed, 19 Dec 2018 16:45:29 -0000, Snicker <snick_at_invalid.invalid> wrote:

Quote:
In article <op.zt928onno5piw3_at_desktop-ga2mpl8.lan>, "William
Gothberg"@internet.co.is says...

On Wed, 19 Dec 2018 16:34:11 -0000, whisky-dave <whisky.dave_at_gmail.com> wrote:

On Wednesday, 19 December 2018 16:21:43 UTC, 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.

You can also observe such things using a smartphone that has a high FPS rate for recodring movie.
I can see the labs lights flicker when I film at 240FPS standard 60 and everything seems fine.

Everybody seems to constantly cut corners. Lights should just be on, no flicker at all. Fucking annoying if you have decent eyesight, I can see the flicker from almost everyone's LED tail lights.

Then stop looking at them.


I value the front of my car.

Rod Speed
Guest

Thu Dec 20, 2018 1:45 am   



"William Gothberg" <"William Gothberg"@internet.co.is> wrote in message
news:op.zt920ry6o5piw3_at_desktop-ga2mpl8.lan...
Quote:
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?


No point when the only thing that has a problem is videos.

You don't even see a problem with dashcams.

Rod Speed
Guest

Thu Dec 20, 2018 1:45 am   



"William Gothberg" <"William Gothberg"@internet.co.is> wrote in message
news:op.zt923mnpo5piw3_at_desktop-ga2mpl8.lan...
Quote:
On Wed, 19 Dec 2018 16:18:29 -0000, Mark Lloyd <not_at_mail.invalid> wrote:

On 12/19/18 5:23 AM, William Gothberg 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.

I once had an audio amplifier with a solar cell rather than a microphone
for the input transducer. This made it possible to listen to light. The
sun is steady, incandescent lights (AC powered) hum.

That was 40 years ago. Maybe something like that would work today.

The trouble is I want to compare 2kHz+ from one light with 2kHz+ from a
neighbouring light and see if they're in sync.


They wont be. They would have to have extra to synch
to the mains and there is absolutely no reason to do that.

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