Warning: LED torches and cap lamps can cause a strobing effect that can
make rapidly turning things like drill chucks and grinder wheels seem to
be turning slowly or not at all.

Bill

Yes they can. I think it has something to do with the fact they do not
actually have any persistence of emission like most tungsten lamps would or
like the coating on many discharge lamps.
I think you would need to be very unlucky to get the strobe speed so near
a rotation speed that it almost stood still though.
Brian

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"Bill Wright" wrote in message
news
Warning: LED torches and cap lamps can cause a strobing effect that can
make rapidly turning things like drill chucks and grinder wheels seem to
be turning slowly or not at all.

Bill

On 29/09/2017 07:23, Brian Gaff wrote:
Yes they can. I think it has something to do with the fact they do not
actually have any persistence of emission like most tungsten lamps would or
like the coating on many discharge lamps.
I think you would need to be very unlucky to get the strobe speed so near
a rotation speed that it almost stood still though.
Brian

What can happen is that when the tool is on load it looks as if the
wheel or chuck is slipping.

Bill

In article ,
Bill Wright wrote:
On 29/09/2017 07:23, Brian Gaff wrote:
Yes they can. I think it has something to do with the fact they do not
actually have any persistence of emission like most tungsten lamps
would or like the coating on many discharge lamps. I think you would
need to be very unlucky to get the strobe speed so near a rotation
speed that it almost stood still though. Brian

What can happen is that when the tool is on load it looks as if the
wheel or chuck is slipping.

You use a torch to light work on a machine tool?

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On Friday, 29 September 2017 14:04:04 UTC+1, Dave Plowman (News) wrote:
In article ,
Bill Wright wrote:
On 29/09/2017 07:23, Brian Gaff wrote:
Yes they can. I think it has something to do with the fact they do not
actually have any persistence of emission like most tungsten lamps
would or like the coating on many discharge lamps. I think you would
need to be very unlucky to get the strobe speed so near a rotation
speed that it almost stood still though. Brian

What can happen is that when the tool is on load it looks as if the
wheel or chuck is slipping.

You use a torch to light work on a machine tool?

The lathes in the basement had lights pointing at the work, especailly the the new digital one we had it did lok like a standard torch had been adapted like the older ones had what looked like adapted angle poised lamps.

In article ,
whisky-dave wrote:
On Friday, 29 September 2017 14:04:04 UTC+1, Dave Plowman (News) wrote:
In article ,
Bill Wright wrote:
On 29/09/2017 07:23, Brian Gaff wrote:
Yes they can. I think it has something to do with the fact they do
not actually have any persistence of emission like most tungsten
lamps would or like the coating on many discharge lamps. I think
you would need to be very unlucky to get the strobe speed so near
a rotation speed that it almost stood still though. Brian

What can happen is that when the tool is on load it looks as if the
wheel or chuck is slipping.

You use a torch to light work on a machine tool?

The lathes in the basement had lights pointing at the work, especailly
the the new digital one we had it did lok like a standard torch had been
adapted like the older ones had what looked like adapted angle poised
lamps.

Quite. But a torch by nature is a battery device. Why would you use a
battery light on a tool driven by mains?

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On 29/09/2017 14:03, Dave Plowman (News) wrote:
In article ,
Bill Wright wrote:
On 29/09/2017 07:23, Brian Gaff wrote:
Yes they can. I think it has something to do with the fact they do not
actually have any persistence of emission like most tungsten lamps
would or like the coating on many discharge lamps. I think you would
need to be very unlucky to get the strobe speed so near a rotation
speed that it almost stood still though. Brian

What can happen is that when the tool is on load it looks as if the
wheel or chuck is slipping.

You use a torch to light work on a machine tool?

I find head torches very good for some machining operations - very good
for keeping the light exactly where you need it and not casting your own
shadow on it.


--
Cheers,

John.

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| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

On 30/09/2017 13:47, John Rumm wrote:
On 29/09/2017 14:03, Dave Plowman (News) wrote:
In article ,
*** Bill Wright wrote:
On 29/09/2017 07:23, Brian Gaff wrote:
Yes they can. I think it has something to do with the fact they do not
actually have any persistence of emission like most tungsten lamps
would or like the coating on many discharge lamps. I think you would
need to be very unlucky to get the strobe* speed so near a rotation
speed that it almost stood still though. Brian

What can happen is that when the tool is on load it looks as if the
wheel or chuck is slipping.

You use a torch to light work on a machine tool?

I find head torches very good for some machining operations - very good
for keeping the light exactly where you need it and not casting your own
shadow on it.


+1 - I've used a Petzl for some 5 years, still going.


--
Cheers, Rob

On 29/09/2017 07:23, Brian Gaff wrote:
Yes they can. I think it has something to do with the fact they do not
actually have any persistence of emission like most tungsten lamps would or
like the coating on many discharge lamps.
I think you would need to be very unlucky to get the strobe speed so near
a rotation speed that it almost stood still though.

It is because a lot of LED torches use a high efficiency switched mode
current drive power supply. A side effect is that the LED brightness is
modulated at a moderately high frequency.

You can see it too on car brake lights and pelican crossings in your
peripheral vision (the strobe rate on them is a bit low for my taste).

--
Regards,
Martin Brown

On 29/09/2017 13:41, Martin Brown wrote:
On 29/09/2017 07:23, Brian Gaff wrote:
Yes they can. I think it has something to do with the fact they do not
actually have any persistence of emission like most tungsten lamps
would or
like the coating on many discharge lamps.
Â* I think you would need to be very unlucky to get the strobeÂ* speed
so near
a rotation speed that it almost stood still though.

It is because a lot of LED torches use a high efficiency switched mode
current drive power supply. A side effect is that the LED brightness is
modulated at a moderately high frequency.

You can see it too on car brake lights and pelican crossings in your
peripheral vision (the strobe rate on them is a bit low for my taste).

Yes, even more so as they pass across your peripheral vision - horrible
and occassionally distracting.

SteveW

"Steve Walker" wrote in message
news
On 29/09/2017 13:41, Martin Brown wrote:
On 29/09/2017 07:23, Brian Gaff wrote:
Yes they can. I think it has something to do with the fact they do not
actually have any persistence of emission like most tungsten lamps would
or
like the coating on many discharge lamps.
I think you would need to be very unlucky to get the strobe speed so
near
a rotation speed that it almost stood still though.

It is because a lot of LED torches use a high efficiency switched mode
current drive power supply. A side effect is that the LED brightness is
modulated at a moderately high frequency.

You can see it too on car brake lights and pelican crossings in your
peripheral vision (the strobe rate on them is a bit low for my taste).

Yes, even more so as they pass across your peripheral vision - horrible
and occassionally distracting.

I dont get that at all, and never did with fluoros either.

On 29/09/2017 04:25, Bill Wright wrote:
Warning: LED torches and cap lamps can cause a strobing effect that can
make rapidly turning things like drill chucks and grinder wheels seem to
be turning slowly or not at all.

Bill

A useful tip, this was a well known issue in factories and workshops
with fluorescent lighting but I'd not heard it before with LED lights.

On 29/09/2017 08:19, Ash Burton wrote:
On 29/09/2017 04:25, Bill Wright wrote:
Warning: LED torches and cap lamps can cause a strobing effect that
can make rapidly turning things like drill chucks and grinder wheels
seem to be turning slowly or not at all.

Bill

A useful tip, this was a well known issue in factories and workshops
with fluorescent lighting but I'd not heard it before with LED lights.

It can be the case with mains powered LED lamps... the frosted glass
type usually less so since they tend to run high frequency switching
PSUs. The filament style sometimes just have the four filaments run in
series with a rectifier - so they can strobe at 100Hz.

Battery ones ought to be ok, unless they are they type that uses a DC/DC
converter to step up the battery voltage.

--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

In article ,
Ash Burton wrote:
On 29/09/2017 04:25, Bill Wright wrote:
Warning: LED torches and cap lamps can cause a strobing effect that
can make rapidly turning things like drill chucks and grinder wheels
seem to be turning slowly or not at all.

Bill

A useful tip, this was a well known issue in factories and workshops
with fluorescent lighting but I'd not heard it before with LED lights.

Decent modern florries run at a much higher frequency than mains and don't
give this effect. And unlike LEDs, the phosphors used have a degree of
persistence, so tend to minimise switching flicker.

--
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Dave Plowman London SW
To e-mail, change noise into sound.

On Friday, 29 September 2017 13:08:29 UTC+1, Dave Plowman (News) wrote:
In article ,
Ash Burton wrote:
On 29/09/2017 04:25, Bill Wright wrote:
Warning: LED torches and cap lamps can cause a strobing effect that
can make rapidly turning things like drill chucks and grinder wheels
seem to be turning slowly or not at all.

Bill

A useful tip, this was a well known issue in factories and workshops
with fluorescent lighting but I'd not heard it before with LED lights.

Decent modern florries run at a much higher frequency than mains and don't
give this effect.

They do.


And unlike LEDs, the phosphors used have a degree of
persistence, so tend to minimise switching flicker.

LEDs tubes are meant to get around this by using a similar coating but as yet I haven't tested this like I have with our labs florry tubes.

unless of course you can explain this

notice the can rate and the light on the monitors case and on the wall behind.

https://www.youtube.com/watch?v=sVNDlV7iaO4
iphone at 240FPS


https://www.youtube.com/watch?v=ws_r6jKRmZU
iphone at 60FPS.

In article ,
whisky-dave wrote:
Decent modern florries run at a much higher frequency than mains and
don't give this effect.

They do.

Not here they don't. My definition of decent is different to yours.

--
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Dave Plowman London SW
To e-mail, change noise into sound.

On Friday, 29 September 2017 15:45:55 UTC+1, Dave Plowman (News) wrote:
In article ,
whisky-dave wrote:
Decent modern florries run at a much higher frequency than mains and
don't give this effect.

They do.

Not here they don't. My definition of decent is different to yours.

I bet you've never tried such a test, and what do you define as decent anyway.
Of course my florry tubes weren't causing any problems either.

On Fri, 29 Sep 2017 16:33:36 +0000, Jethro_uk wrote:

Does anyone remember those fancy record decks which had a strobe speed
adjustment ? I had a brief smug moment when I bought (it may have come
with a magazine) a printed disc which you could put on the turntable. It
had markings to stand still at the 33/45 rpm mark.

Garrard 401. I used to sell them.

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wish to copy them they can pay me £1 a message.
Use the BIG mirror service in the UK: http://www.mirrorservice.org
*lightning surge protection* - a w_tom conductor

In article ,
Jethro_uk wrote:
Does anyone remember those fancy record decks which had a strobe speed
adjustment ? I had a brief smug moment when I bought (it may have come
with a magazine) a printed disc which you could put on the turntable. It
had markings to stand still at the 33/45 rpm mark.

Briefly smug, because as a friend pointed out, while I knew my turntable
was out of whack, I had no means of adjusting it. (Insulating tape
around the drive spindle was not a success )

But mains frequency isn't always exactly 50 Hz. A high quality turntable
could well be more accurate than that strobe.

--
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Dave Plowman London SW
To e-mail, change noise into sound.

In article ,
Jethro_uk wrote:
When my Dad had his lathe delivered in the late 70s (who do you think
taught me the importance of the right tool for the right job ?) I
remember the delivery guy commenting that we should fit something to the
power supply to de-phase it from the lights. (Or maybe something to the
lights). He had the mandatory tale of seeing someone put their face into
a spinning lathe.

TV cameras are very sensitive to the flicker from basic tubes. So they
tend to have to be changed less efficient high persistance ones if forced
to use this type of lighting on say a location.

One real problem was boxing matches where the ring lighting is designed by
the boxing authority, and is fluorescent. The answer was to use a three
phase supply with alternate phase feeding adjacent tubes.

--
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Dave Plowman London SW
To e-mail, change noise into sound.

"Tim Streater" wrote in message
.. .
When my Dad had his lathe delivered in the late 70s (who do you think
taught me the importance of the right tool for the right job ?) I remember
the delivery guy commenting that we should fit something to the power
supply to de-phase it from the lights. (Or maybe something to the lights).
He had the mandatory tale of seeing someone put their face into a spinning
lathe.

My grandpa had various fluorescent tubes (full-length 5-foot ones on the
ceiling and shorter 2-foot ones that plugged into bayonet fittings)
illuminating his garage where he had his lathe, but he also had an
anglepoise lamp with a low-power tungsten bulb to illuminate the work. I
remember him telling me (and showing me) why the tungsten one was necessary,
to avoid strobe-freezing. It also provided useful back-lighting and shadows
which made the swarf a bit easier to see as it was coming off.


Does anyone remember those fancy record decks which had a strobe speed
adjustment ?

Yes, I still have one (haven't used it for about 25 years tho). Has a
strobe built in an you can adjust the speed up/down. And set it for
60Hz if you happen to take it there. It's a Thorens TD135 II.

My dad's B&O turntable had those strobe markings - it had two scales, one
for 50 Hz and one for 60 Hz mains. I was surprised how sharp the markings
were - not much wider when rotating than when stationary, given that
tungsten lights stay alight a lot longer than fluorescents on each mains
cycle.

In article ,
Tim Streater wrote:
In article , Jethro_uk
wrote:

On Fri, 29 Sep 2017 18:04:31 +0100, Tim Streater wrote:

In article , Jethro_uk
wrote:

On Fri, 29 Sep 2017 08:19:26 +0100, Ash Burton wrote:

On 29/09/2017 04:25, Bill Wright wrote:
Warning: LED torches and cap lamps can cause a strobing effect
that can make rapidly turning things like drill chucks and grinder
wheels seem to be turning slowly or not at all.

Bill

A useful tip, this was a well known issue in factories and
workshops with fluorescent lighting but I'd not heard it before
with LED lights.

When my Dad had his lathe delivered in the late 70s (who do you think
taught me the importance of the right tool for the right job ?) I
remember the delivery guy commenting that we should fit something to
the power supply to de-phase it from the lights. (Or maybe something
to the lights). He had the mandatory tale of seeing someone put their
face into a spinning lathe.

Does anyone remember those fancy record decks which had a strobe
speed adjustment ?

Yes, I still have one (haven't used it for about 25 years tho). Has a
strobe built in an you can adjust the speed up/down. And set it for
60Hz if you happen to take it there. It's a Thorens TD135 II.

Now there's a name I haven't heard for .... over 30 years.

Oops, TD125 II sorry.

The true reason for the speed adjustment on a TD 125 was not to adjust it
to a true 33 1/3 or whatever speed, but to allow adjustment where the
speed and therefore pitch of the recording was incorrect. Quite common
with older recordings. Which is why is was called a transcription deck.

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Dave Plowman London SW
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