[HN Gopher] Ask HN: Why is coil whine in electronics so prevalent?
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Ask HN: Why is coil whine in electronics so prevalent?
I'm talking about the whine, buzzing and similar noises. Here's an
explanation of how they happen:
https://www.youtube.com/watch?v=4D6PKusyvUU. Now, I've heard of
some simple DIY remedies that work, like putting glue in/around the
inductors. So, I want to know why this doesn't get properly fixed
in the manufacturing process. Because nobody cares? Is it too
costly? I wouldn't mind paying a small price premium for a product
if there was a guarantee of no coil whine.
Author : whyoh
Score : 10 points
Date : 2022-11-06 21:29 UTC (1 hours ago)
| askiiart wrote:
| Relatedly: why is flickering LEDs so common? I presume most
| people also just don't see/don't care?
| hongtona wrote:
| rowinofwin wrote:
| If you want to have a range of brightness you have a couple of
| options. One option is to vary the voltage you supply to the
| led, leading to a reduced brightness at lower voltages. The
| alternative is to use pulse width modulation, basically turning
| the led on and off fast so that it is on for a percentage of
| the time at full power.
|
| Going with lower voltage is less efficient as the LED will
| output less light per voltage but not linearly, it will still
| use most of the power of full brightness at half.
|
| Choosing PWM allows you to skip this problem by keeping the
| voltage identical but by using human persistence of vision to
| get the ideal number of photons to your eyes per your
| perception frame. The problem comes from making a slow PWM
| signal, say 60Hz, or having two similar but not identical PWM
| signals near each other, such as two different TV screens with
| a different backlight PWM frequency. That can make you see
| flashing because of the out of phase brightness peaks and
| troughs lining up.
| derkades wrote:
| > Going with lower voltage is less efficient as the LED will
| output less light per voltage but not linearly, it will still
| use most of the power of full brightness at half.
|
| I don't think this is true? Aren't LEDs _more_ efficient at
| lower voltages /currents?
| throwaway821909 wrote:
| I've noticed a couple of LED bulbs (one with warnings that
| it's non-dimmable) where the PWM (presumably) means that even
| when I'm not looking for it, I'll move my hand quickly to
| grab something and it looks like I'm in a 20fps computer
| game, fun novelty but it wears off. Fortunately there are
| plenty where I don't see this.
| briHass wrote:
| I don't think this is the flickering the original poster is
| referring to. Dimmers are a bit of a nightmare with LEDs,
| however. I usually buy high quality (pricey) dimmer switches
| and good quality LEDs that are listed by the dimmer as
| compatible.
|
| The flicker that bothers me, and maybe the GP, is likely due
| to cost cutting in the LED power supply. Not enough filtering
| or ability to handle the normal voltage dips in a home
| electrical system. As above, the solution is usually to spend
| more $ on bulbs, but not a guarantee.
| hulitu wrote:
| > So, I want to know why this doesn't get properly fixed in the
| manufacturing process. Because nobody cares? Is it too costly? I
| wouldn't mind paying a small price premium for a product if there
| was a guarantee of no coil whine.
|
| It is too costly. You want a low frequency to be good at EMC (
| i.e. FCC regulations) and you want higher frequency to spare
| money on components. Easiest is low frequency and hope for the
| best. Nobody cares about your ears as long as there is no
| regulation specifying noise. And glueing is expensive and, in the
| long term, might not bring any improuvment.
| cinntaile wrote:
| Especially those remote controlled light bulbs. Why is that a
| thing? Who wants to have a constant buzzing sound in the
| background when the light is turned off using the remote.
| PaulHoule wrote:
| Mostly people don't care.
|
| When I was a kid I asked adults about that whine from TV sets and
| none of them knew what I was talking about. The conventional
| answer was that adults have a hard time hearing the 15khz whine
| due to age related hearing loss but I am older than my parents
| were back then and I still hear it just fine on those rare
| occasions I get near a CRT.
| whyoh wrote:
| Right, most people aren't bothered by it or don't even hear it.
| I see a lot of complaints online, though, so there might be a
| market for whine-free equipment. It's quite annoying when you
| have to record some audio with sensitive mics. Even LED bulbs
| and PC monitors can emit audible noise.
| brudgers wrote:
| It's safe to assume that the viable market demand is already
| met by existing products.
|
| By 'viable' I mean that companies can charge enough to remain
| in business by catering to a market segment that is willing
| and able to pay for the differentiation at margins sufficient
| to maintain the boutique sales channels necessary for low
| volume specialty goods.
|
| Basically it is analogous to the audiophile market where
| discerning listeners are expected to pony up thousands of
| dollars on each piece of gear.
|
| That's my take.
|
| YMMV.
| PaulHoule wrote:
| My experience too is that you face a lot of gaslighting
| whenever you have non functional requirements.
|
| Back when the Athlon 64 was new I was very annoyed by noisy
| desktop computers and went through great expense and
| trouble to pick out quiet parts for a PC, frequently I
| found the reviews of quiet PC parts from sites like Tom's
| Hardware were just plain wrong and that from the power
| supply to fans and hard drives I had to try multiple parts
| before I got something really quiet.
|
| I am thinking about building a new PC but I haven't done it
| for years since I was so traumatized.
| gardenfelder wrote:
| Two google queries: low frequency transformer whine AND low
| frequency electronic whine will get you much closer to an answer.
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(page generated 2022-11-06 23:01 UTC)