Do switch mode power supplies flicker in time with mains?

[William Gothberg]

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.

 

[Peeler]

On Wed, 19 Dec 2018 22:51:35 +1100, cantankerous trolling geezer Rot Speed,
the auto-contradicting senile sociopath, blabbered, again:

No.

Trust that senile Ozzietard Rot will be the first to run along and suck off
the Scottish wanker and attention whore again! LOL

--
The Natural Philosopher about senile Rot:
"Rod speed is not a Brexiteer. He is an Australian troll and arsehole."
Message-ID: <pu07vj$s5$2@dont-email.me>

 

[Peeler]

On Wed, 19 Dec 2018 11:23:00 -0000, Birdbrain Macaw (now "James Wilkinson",
"Steven Wanker","Bruce Farquar", "Fred Johnson, etc.), the pathological
resident idiot and attention whore of all the uk ngs, blathered again:

<FLUSH the abnormal sociopathic attention whore's latest idiotic
attention-baiting bullshit unread again>


--
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trolling:
"He is a well known attention seeking troll and every reply you
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Starts many threads most of which die quick as on the UK groups anyone
with sense Kill filed him ages ago which is why he now cross posts to
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This thread was unusual in that it derived and continued without him
to a large extent and his silly questioning is an attempt to get
noticed again."
MID: <be195d5jh0hktj054mvfu7ef9ap854mjdb@4ax.com>

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You have been presented with a viewpoint with information, reasoning,
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MID: <KaToA.263621$g93.262397@fx10.am4>

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several parrots living in his hovel."
MID: <odqtgc$iug$1@dont-email.me>

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MID: <20170519215057.56a1f1d4@Mars>

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MID: <0001HW.1EE2D20300E7BECC700004A512CF@news.eternal-september.org>

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MID: <rOmdndd_O7u8iK7EnZ2dnUU78TGdnZ2d@brightview.co.uk>

--
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"What, were you dropped on your head as a child?"
MID: <58ddfad5-d9a5-4031-b91f-1850245a6ed9@googlegroups.com>

--
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month some time. You're like a dog who's just dug up an old bone they
hid in the garden until they were ready to have another go at it."
MID: <59d8b0db.4113512@news.eternal-september.org>

--
Mr Pounder's fitting description of Birdbrain Macaw:
"You are a well known fool, a tosser, a pillock, a stupid unemployable
sponging failure who will always live alone and will die alone. You will not
be missed."
MID: <orree6$on2$1@dont-email.me>

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"You haven't bred?
Only useful thing you've done in your pathetic existence."
MID: <orvctf$l5m$1@gioia.aioe.org>

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and bandwidth."
MID: <s5e9uclqpnabtehehg3d792tmll73se0g8@4ax.com>

--
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MID: <os5m1i$8m1$1@dont-email.me>

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MID: <cf06cdd9-8bb8-469c-800a-0dfa4c2f9ffa@googlegroups.com>

--
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"If people like JWS didn't exist, we would have to find some other way to
explain the concept of "invincible ignorance"."
MID: <otofc8$tbg$2@dont-email.me>

 

[William Gothberg]

On Wed, 19 Dec 2018 11:56:43 -0000, Adrian Caspersz <email@here.invalid> wrote:

On 19/12/2018 11:23, William Gothberg wrote:
Do switch mode power supplies flicker in time with mains? Specifically
LED power supplies in commercially available domestic lamps.

Look at the infantile name of the poster,

It's just a name.

> the crossposting,

To find more people who might know the answer.

> the stupid question.

It's a perfectly sensible question, I want to know if with a lot of similar LED lights, if the whole room will experience flicker.

> before ye answer, it's hucker again...

So what?

 

[William Gothberg]

On Wed, 19 Dec 2018 11:51:35 -0000, Rod Speed <rod.speed.aaa@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. 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) and fudge the brightness together.

 

[Rod Speed]

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.

 

[Rod Speed]

"William Gothberg" <"William Gothberg"@internet.co.is> wrote in message
newsp.zt9qc10co5piw3@desktop-ga2mpl8.lan...

On Wed, 19 Dec 2018 11:51:35 -0000, Rod Speed <rod.speed.aaa@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.

> and fudge the brightness together.

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

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.

 

[William Gothberg]

On Wed, 19 Dec 2018 12:28:04 -0000, Rod Speed <rod.speed.aaa@gmail.com> wrote:

"William Gothberg" <"William Gothberg"@internet.co.is> wrote in message
newsp.zt9qc10co5piw3@desktop-ga2mpl8.lan...
On Wed, 19 Dec 2018 11:51:35 -0000, Rod Speed <rod.speed.aaa@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, and all the lights were switched on at the same time (with one lightswitch), they should remain in synch forever. But since there are tolerances in all the components in the PSUs, they won't stay in time.

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

 

[Peeler]

On Wed, 19 Dec 2018 23:28:04 +1100, cantankerous trolling geezer Rot Speed,
the auto-contradicting senile sociopath, blabbered, again:

<FLUSH the two prize idiots' endless idiotic drivel unread again>

--
Typical retarded "conversation" between the Scottish wanker and senile
Ozzietard:

Birdbrain: "Horse shit doesn't stink."

Senile Rot: "It does if you roll in it."

Birdbrain: "I've never worked out why, I assumed it was maybe meateaters
that made stinky shit, but then why does vegetarian human shit stink? Is it
just the fact that we're capable of digesting meat?"

Senile Rot: "Nope, some cow shit stinks too."

Message-ID: <fv5f1tFi3f2U1@mid.individual.net>

 

[Mark Lloyd]

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.

--
6 days until the winter celebration (Tue Dec 25, 2018 12:00:00 AM for 1
day).

Mark Lloyd
http://notstupid.us/

"Do not thank God for what man does." [Lemuel K. Washburn, _Is The Bible
Worth Reading And Other Essays_, 1911]

 

[Mark Lloyd]

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.

[snip]

--
6 days until the winter celebration (Tue Dec 25, 2018 12:00:00 AM for 1
day).

Mark Lloyd
http://notstupid.us/

"Do not thank God for what man does." [Lemuel K. Washburn, _Is The Bible
Worth Reading And Other Essays_, 1911]

 

[Andy Burns]

Mark Lloyd wrote:

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.

Certainly if you connect a solar cell to an oscilloscope, you can see
the difference between

incandescent and LED GU10 lamps fed 240V mains

incandescent and LED MR16 lamps fed 12V from an electronic 'transformer'

a dimmer feeding either of the above.

 

[William Gothberg]

On Wed, 19 Dec 2018 16:21:41 -0000, Mark Lloyd <not@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?

 

[William Gothberg]

On Wed, 19 Dec 2018 16:18:29 -0000, Mark Lloyd <not@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.

 

[William Gothberg]

On Wed, 19 Dec 2018 16:34:11 -0000, whisky-dave <whisky.dave@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.

 

[Brian Gaff]

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...
The Sofa of Brian Gaff...
briang1@blueyonder.co.uk
Blind user, so no pictures please
Note this Signature is meaningless.!
"William Gothberg" <"William Gothberg"@internet.co.is> wrote in message
newsp.zt9okmwvo5piw3@desktop-ga2mpl8.lan...

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]

In article <op.zt928onno5piw3@desktop-ga2mpl8.lan>, "William
Gothberg"@internet.co.is says...

On Wed, 19 Dec 2018 16:34:11 -0000, whisky-dave <whisky.dave@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]

"William Gothberg" <"William Gothberg"@internet.co.is> wrote in message
newsp.zt9sk9gco5piw3@desktop-ga2mpl8.lan...

On Wed, 19 Dec 2018 12:28:04 -0000, Rod Speed <rod.speed.aaa@gmail.com
wrote:



"William Gothberg" <"William Gothberg"@internet.co.is> wrote in message
newsp.zt9qc10co5piw3@desktop-ga2mpl8.lan...
On Wed, 19 Dec 2018 11:51:35 -0000, Rod Speed <rod.speed.aaa@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.

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.

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]

On 12/19/2018 11:36 AM, William Gothberg wrote:

On Wed, 19 Dec 2018 16:18:29 -0000, Mark Lloyd <not@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]

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

"William Gothberg" <"William Gothberg"@internet.co.is> wrote in message
newsp.zt9sk9gco5piw3@desktop-ga2mpl8.lan...
On Wed, 19 Dec 2018 12:28:04 -0000, Rod Speed <rod.speed.aaa@gmail.com
wrote:



"William Gothberg" <"William Gothberg"@internet.co.is> wrote in message
newsp.zt9qc10co5piw3@desktop-ga2mpl8.lan...
On Wed, 19 Dec 2018 11:51:35 -0000, Rod Speed <rod.speed.aaa@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.

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.

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?

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.