XPost: alt.home.repair, uk.d-i-y
From: rod.speed.aaa@gmail.com
"William Gothberg" <"William Gothberg"@internet.co.is> wrote in message
news:op.zuabbpuro5piw3@desktop-ga2mpl8.lan...
> On Wed, 19 Dec 2018 18:33:09 -0000, Rod Speed
> wrote:
>
>>
>>
>> "William Gothberg" <"William Gothberg"@internet.co.is> wrote in message
>> news:op.zt9sk9gco5piw3@desktop-ga2mpl8.lan...
>>> On Wed, 19 Dec 2018 12:28:04 -0000, Rod Speed
>>> wrote:
>>>
>>>>
>>>>
>>>> "William Gothberg" <"William Gothberg"@internet.co.is> wrote in message
>>>> news:op.zt9qc10co5piw3@desktop-ga2mpl8.lan...
>>>>> On Wed, 19 Dec 2018 11:51:35 -0000, Rod Speed
>>>>>
>>>>> 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.
Because you were silly enough to buy the cheapest
shit when your eyes can see the flicker.
> Shouldn't they fill in each other's gaps?
Nope, because there will always be some places
where something is primarily illuminated by the
one light and so you will see that flicker, even
if ensure you can never see the bulb itself and
I bet you can actually see the bulbs directly.
>>> 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.
You should be able to see the visible effect change as
you move the rotating chuck from under one light to
under another, particularly as you go from one to
another with the chuck illuminated by two lights.
Its academic anyway, there is no way that your
cheap leds will be deliberately synched to the
mains, because it costs more to do that.
> I'm not going to be able to tell the difference between them with
> something as simple as a drill chuck.
Yes you are when you can see the strobe effect with the drill chuck.
> Presumably they're something like 1995 Hz, 2001 Hz, 2003 Hz, etc.
Yes.
> All I can think of to prove it would be a higher speed camera so I can
> spot them being on at different times.
And if you had a decent smartphone you could do that
with that, but since you are too stupid to have one...
--- SoupGate-Win32 v1.05
* Origin: you cannot sedate... all the things you hate (1:229/2)
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