Is it Okay for Switched-Mode Power Supplies to Make Noise?

[DIYLED]

Does this affect the lifetime of the power supply? I'm not talking about the cheap ones, this happened to me with the Meanwell HLG series in an art installation. It was like a symphony of the same high pitch coming from various different places as the LED strips changed colors and brightnesses. Probably the same pitch as the DMX decoders/dimmers' PWM frequency. From what I've been reading online, this happens sometimes and is a nuisance, but nobody really talks about the effect on reliability and longevity. Apparently, it's either a piezoelectric effect in ceramic capacitors or a magnetic force from inductors. The noise itself doesn't matter to me, I just don't want the power supplies to fail in a few months.

This has happened to me only once in the past, and I eliminated the noise, practically speaking, by wiring low-ESR capacitors between DC ground and the load side of the fuses, so basically between the DC terminals plus the resistances of the fuses. That may not be a good solution in this particular case because it can increase inrush currents at turn-on, unless I add creative switches that won't spark and blow the fuses, and the installation is in another state but I'm back home now.

Any thoughts? Everything is within the ratings of the devices.

 

[porkchop]

I've got bad news for you. Meanwell are cheap power supplies. Good enough to be used professionally, and a huge improvement over what you find on eBay, but nothing I wuld use for critical equipment. They're my go to for LED lighting, but for automation stuff I look towards Omron or TDK.

To answer your question this will be fine until it isn't. Your power supplies will probably not last as long as similar models that don't ring, but I would still expect them to take a significant duty cycle for quite a while. Burning out in a few months would be a really short lifetime unless you're pulling close to or over rated current 24/7.

 

[DIYLED]

Thanks for the bad news. It's a good thing we left some extras. And thanks for recommending a couple brands. In the programming there are rare and brief moments where it draws 90% of max current but generally draws 30 to 60% and at times nearly 0%. The ringing I believe was at dimmed levels, not full brightness.

I've used the HLG series for years and numerous units have worked reliably except for 1 that was dead-on-arrival but promptly replaced by the Meanwell distributor. That series has a 7-year warranty. They have never made noise before, but maybe the new 480H size is different? Curious if anybody else has noticed this.

The LPV series has also worked flawlessly for me for years. The only other time I heard noise was I believe the NPF series.

On another forum in an old thread, somebody said that long wires can cause power supply noise. I'm not sure how that works or if that's even accurate.

 

[porkchop]

I don't mean to say don't buy Meanwell. They come at a great price and are well known enough that you can trust them to not electrocute someone, but they're also the only PSU that I've seen explode at power up (6ish year old 480VAC to 24VDC, usage was low load but 100% duty cycle, man was it loud). I've specified hundreds of them for various lighting projects and continue to go to them first for things like LEDs that are pretty tolerant of power oddities and non-critical. I'm just not surprised if they aren't as stable or don't last as long as brands that charge more for a higher quality.

 

[DIYLED]

Wow that's wild. I didn't know any of the Meanwell's were rated for 480VAC.

 

[Harrison Hohnholt]

It was like a symphony of the same high pitch coming from various different places as the LED strips changed colors and brightnesses. Probably the same pitch as the DMX decoders/dimmers' PWM frequency.

Are you sure it isn't the mosfets on the dimmer? I have dimmers sing all the time, I haven't heard a power supply sing though. When its the dimmer I just up the PWM and it goes out of the range of human hearing.

 

[JD]

Although much smaller because of the high frequency, switch-mode power supplies still contain a transformer. A Transformer is a metal core with wingdings wrapped around it, in other words, the same elements as a loudspeaker. (reversed) In any case, they will make noise. Efforts are made to minimize any motion, such as tight wrapping, glue, sometimes flat-out potted. The more money available, the more can be spent on vibration suppression. Often, these things operate well above human hearing, so, why can you hear them? Several reasons. The frequency may be modulated as it nears its rated voltage output, or sometimes stopped and started. This may sound like a tick..tick..tick, but often the stop & start may happen many thousands of times a second, and vary in frequency as the load changes. Is it harmful? No. Unless the wingdings are moving so much they are knocking the insulation off of each other, it is harmless. The noise may not be limited to just the core and winding. If the case around it is made of steel, the changing magnetic field may actually induce sound in the case, which will serve as a diaphragm. Switch mode supplies may go on for many many years, but always live their lives milliseconds away from death! (such is the nature of saturating such a small core.) Often, the failure may be a secondary diode. Then you will really hear it squeal! (or it will begin cycling.)

 

[Les]

I don't mean to say don't buy Meanwell. They come at a great price and are well known enough that you can trust them to not electrocute someone, but they're also the only PSU that I've seen explode at power up (6ish year old 480VAC to 24VDC, usage was low load but 100% duty cycle, man was it loud). I've specified hundreds of them for various lighting projects and continue to go to them first for things like LEDs that are pretty tolerant of power oddities and non-critical. I'm just not surprised if they aren't as stable or don't last as long as brands that charge more for a higher quality.

No need to justify yourself. We know you meanwell.

And to add something to this thread aside from a terrible pun, I've had a TDK-Lambda LVS in a Varilite squeal. I had a spare, so I swapped it out for good measure. Interestingly, the exact replacement was silent.

 

[Jay Ashworth]

Dimmers always make the most noise mid-range.

But the PWM freq is often 400-600Hz; it was probably the oscillator freq of the switcher, up past 10k.

 

[RonHebbard]

Although much smaller because of the high frequency, switch-mode power supplies still contain a transformer. A Transformer is a metal core with wingdings wrapped around it, in other words, the same elements as a loudspeaker. (reversed) In any case, they will make noise. Efforts are made to minimize any motion, such as tight wrapping, glue, sometimes flat-out potted. The more money available, the more can be spent on vibration suppression. Often, these things operate well above human hearing, so, why can you hear them? Several reasons. The frequency may be modulated as it nears its rated voltage output, or sometimes stopped and started. This may sound like a tick..tick..tick, but often the stop & start may happen many thousands of times a second, and vary in frequency as the load changes. Is it harmful? No. Unless the wingdings are moving so much they are knocking the insulation off of each other, it is harmless. The noise may not be limited to just the core and winding. If the case around it is made of steel, the changing magnetic field may actually induce sound in the case, which will serve as a diaphragm. Switch mode supplies may go on for many many years, but always live their lives milliseconds away from death! (such is the nature of saturating such a small core.) Often, the failure may be a secondary diode. Then you will really hear it squeal! (or it will begin cycling.)

@JD "wingdings" ?? Really??? I'll buy windings but I'm suspecting "wingdings" may be a typo.
Toodleoo!
Ron Hebbard

 

[JD]

@JD "wingdings" ?? Really??? I'll buy windings but I'm suspecting "wingdings" may be a typo.
Toodleoo!
Ron Hebbard

Ha! I must have been hungry went I wrote this! Yea, spell-correct can make for some interesting comments! Do they still sell Wingdings, or did that get dumped when Hostess was bought out? Used to love them.

 

[derekleffew]

Finally! Someone other than me notices wingdings/windings. Wingdings is a font family of mostly symbols.

To try to bring this back to topic, sort of...
For the past 20-25 years, I've had the same Mr. Coffee machine. Ever since I got it, occasionally I'd notice it "buzzing," a 60-Hz hum. Giving it a good sharp slap right on top would stop the buzzing, often for a week or more. Who knows what's going on with that? I rarely use the thing, preferring now a single-cup pour-over that's better suited to my needs and tastes. I probably should unplug it, but don't want to have to set the clock in the rare instances I use it. Yes yes, quiescent power and all that.

 

[JD]

Finally! Someone other than me notices wingdings/windings. Wingdings is a font family of mostly symbols.

To try to bring this back to topic, sort of...
For the past 20-25 years, I've had the same Mr. Coffee machine. Ever since I got it, occasionally I'd notice it "buzzing," a 60-Hz hum. Giving it a good sharp slap right on top would stop the buzzing, often for a week or more. Who knows what's going on with that? I rarely use the thing, preferring now a single-cup pour-over that's better suited to my needs and tastes. I probably should unplug it, but don't want to have to set the clock in the rare instances I use it. Yes yes, quiescent power and all that.

View attachment 16724

I should just turn spell-check off and be happy misspelling every third word!
As for your coffee maker, it is old enough that it probably uses a regular transformer to provide low voltage to the program/display. The core is loose. Depending on how far you want to move if from its UL approval, it can be fixed with either a squirt of GE silicon, or shove a toothpick in it! Probably time for a new coffee maker anyhow! Hope you're not doing the Keurig mold breeder!

 

[DIYLED]

That was a fun distraction, but I was expecting Derek to say that he ate wingdings when he drank the coffee. This is making me hungry.

A lot of food for thought on the noise issue. Thanks for the replies.

I'm not 100% sure it was the power supplies because I had finished working after midnight and caught an airplane in the morning. The project was really down to the wire because of an unexpected (unrelated) issue that had to be solved. I never really put my ear close enough to tell if it was the PSU's or the dimmers, didn't know that DC dimmers and MOSFET's could make noise. I have used these same dimmers before, and they have never made noise. The frequency options are 250 Hz and 5,000 Hz, and I had selected 5,000 Hz.
https://www.environmentallights.com/17455-dmx-24-5000-4a.html

I'll see if I can replicate the issue but may have to re-order the same power supply.

 

[JD]

That was a fun distraction, but I was expecting Derek to say that he ate wingdings when he drank the coffee. This is making me hungry.

A lot of food for thought on the noise issue. Thanks for the replies.

I'm not 100% sure it was the power supplies because I had finished working after midnight and caught an airplane in the morning. The project was really down to the wire because of an unexpected (unrelated) issue that had to be solved. I never really put my ear close enough to tell if it was the PSU's or the dimmers, didn't know that DC dimmers and MOSFET's could make noise. I have used these same dimmers before, and they have never made noise. The frequency options are 250 Hz and 5,000 Hz, and I had selected 5,000 Hz.
https://www.environmentallights.com/17455-dmx-24-5000-4a.html

I'll see if I can replicate the issue but may have to re-order the same power supply.

Yea, it's PWM, which means each driver has a choke in series to remove RF content. Choke = WINDINGS around a metal core. (ignoring spell check )

 

[n1ist]

It can also be ceramic or some poly capacitors; they can act as piezo tweeters... We had to goop the ones in the Proflex dimmers to keep them quiet. Real fun when you have multiple power supplies making noise and you are hearing the beat frequency wander around.

/mike

 

[digital1]

Does this affect the lifetime of the power supply? I'm not talking about the cheap ones, this happened to me with the Meanwell HLG series in an art installation. It was like a symphony of the same high pitch coming from various different places as the LED strips changed colors and brightnesses. Probably the same pitch as the DMX decoders/dimmers' PWM frequency. From what I've been reading online, this happens sometimes and is a nuisance, but nobody really talks about the effect on reliability and longevity. Apparently, it's either a piezoelectric effect in ceramic capacitors or a magnetic force from inductors. The noise itself doesn't matter to me, I just don't want the power supplies to fail in a few months.

This has happened to me only once in the past, and I eliminated the noise, practically speaking, by wiring low-ESR capacitors between DC ground and the load side of the fuses, so basically between the DC terminals plus the resistances of the fuses. That may not be a good solution in this particular case because it can increase inrush currents at turn-on, unless I add creative switches that won't spark and blow the fuses, and the installation is in another state but I'm back home now.

Any thoughts? Everything is within the ratings of the devices.

 

[digital1]

The sound is coming from electro magnetic vibrations caused by the ON & OFF cycles caused by the PWM dimming. It is the audible harmonics of the combination of the PWM frequency and the internal frequency of the switching power supply
This should not reduce the life of the Meanwel power supply if its internal dimmer is designed correctly.

 

[eadler]

Although much smaller because of the high frequency, switch-mode power supplies still contain a transformer. A Transformer is a metal core with wingdings wrapped around it, in other words, the same elements as a loudspeaker. (reversed) In any case, they will make noise. Efforts are made to minimize any motion, such as tight wrapping, glue, sometimes flat-out potted.

Exactly, JD. We have a well known high-end audio equipment manufacturer down the road here that actually uses tar around all of their transformers as the tar absorbs the vibrations rather than trying to completely bind the transformer plates together. (I'm sure they explain it much more eloquently and proper than that).

 

[ship]

Thanks all, never seen this problem but learned a lot - mostly over my head but enough of a kernel it helps.