# Quiet 12v Power Supplies for LED strips



## TheGiantHogweed (Feb 20, 2020)

I am having a lot of difficulty in getting what seems a good quality 12v power supply. I wondered weather to ask here or on headfi as I also use them for audio stuff too.

The problem I have is that I am incredibly sensitive to sound. I find the high pitched buzz emitted from a lot of power supplies almost unbearable even if it is pretty quiet. The issue with using them with LEDs is that dimming only makes the noise change and generally get louder. I have bought many from different places, some of which turn out to be suitable if the LEDs are used on full power, but produce a horrible noise when dimmed. It also brings the noise of the power supply to the dimmer itself, making it even harder to hide the noise. Interesting thing is that some old 12v power supplies i had lying around seem to be really good quality. For example an LG 12v 2A power supply that came with an optical drive for a PC, this one makes no audible noise what so ever, even when dimming. I tend to find that the sort with an mains lead to the transformer tend to be better built and emit less noise, but that is not always the case. All of the good ones I have are what happened to not be needed as the device they came with either no longer worked or was not used. As I find is the case with most things built these days including power supplies, they used to be built better. This LG one will probably be nearly 15 years old. 

Out of all the ones i have bought being over 3a in the last few years have been noisy in some way. Either the whole time or when the LEDs are dimmed. 

https://www.amazon.co.uk/gp/product/B071VW5R3P/

https://www.ebay.co.uk/itm/DC-12V-1...=174061254712e4ce5b151f68419ca2215588c9688679

I bought a couple from ebay and probably should have known better. I usually notice suspicious things in pictures, but i didn't until I received it and found out that the earth pin was sleeved. That surprised me as they are selling something that is illegal to ship from this country. Anyway, I tried the transformers with my own IEC leads, and they both did the job, but were so noisy. I'm going to request a refund for both anyway as they shouldn't be sold.

So far, going cheap or expensive, I can't seem to find any new 12v power supplies that don't make any audible noise. I just have to keep looking around and using ones from dead equipment that used them as branded ones (that are not sold separately) seem far better.

I have the same problem with 12v audio amplifiers. The amount of noise most power supplies send to the speakers is awful, but it amazes me how good a dirt cheap amplifier can sound if you use a good supply like my LG one.


Any advice on where to buy good 12v power supplies would be appreciated, Thanks.


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## neverdie (Feb 23, 2020)

Mean Well generally makes quality power supplies. You can buy from amazon or digikey or mouser.

Alternatively, you could take a computer power supply brick and use a step down converter to get the voltage you want.


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## TheGiantHogweed (Mar 10, 2020)

Sorry for the late response. I will see if i can look more into some power supplies from the brand that you mention. From what I have seen so far, it tends to be more the open sort rather than enclosed in a case. Regarding computer power supplies, I either have some old ones lying around or should be able to get one elsewhere. But they are pretty large and may seem a bit inappropriate for powering a simple 12v light in a bedroom for example, especially if you have to use a step down converter. But I may remember to use something like this for other purposes. For power supplies in general, the most ideal sort is just a simple 12v brick, just a quiet one. I have seen quite a few Mean Well supplies that are around the right current output but are open so for the area I would use them, they will need to be put in some case. I'm not good at making things myself so are there cases that you can get that could fit them? Although then I would run into the issue of needing to create a cable grip (or an IEC input or something similar), especially on the mains input side. I can picture all of this from power supplies i have opened up, but don't know how easily I could put together myself.


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## DIWdiver (Mar 10, 2020)

It sounds like what you need is an old-fashioned linear supply with electrolytic caps. Most modern supplies are switchers, (including the ones you linked) because they've gotten cheaper to build than linears.

While the switching frequencies are almost always well above the audio range (50 kHz would be quite low, some are over 1 MHz), the PWM frequencies are usually right in the audio band, 200-5000 Hz. Ceramic caps that are so popular now can have a piezoelectric effect, where they change shape with applied voltage. Inductors can have electromagnetically induced mechanical motion as well. I once designed an LED driver that had to have the caps switched from ceramic to more expensive electrolytic ones to eliminate the whine from the caps.

A computer power supply might be okay as well, if the noise from that doesn't bother you. AT type ones have a pretty beefy 12V output and probably electrolytic caps.

Another possibility is to put a filter between the power supply and the dimmer, to reduce the audio frequency load on the power supply. Even a couple of low-impedance electrolytic caps across the output might help.


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## TheGiantHogweed (Mar 11, 2020)

EDIT: This doesn't seem to let me split my post in to paragraphs or start on the next line despite me editing and previewing with it looking correct several times, so sorry if it looks a mess. Starts here >> Interesting. When I think about it, this 2A LG power supply came with an external optical disk drive from 2007. I have plenty of other power supplies that I am not aware of what they came with that seem to be just as good as this one noise wise and I assume they are also pretty old. They also have a good weight to them. That is another think i notice. If they don't weigh much, they usually are more noisy. I don't know enough about the components inside to know why though. I have always been into my sound and have extremely sensitive hearing. I am in my early 20s and I can still hear just over 17khz. Interestingly, using the same site with the test tones and same headphones, I can remember a few years ago, I could hear up to 19khz, so it obviously has dropped off a bit. But I still think I am far more sensitive than the average person. For example, a lot of the time I go into shops that happen to be using an old CRT display for their CCTV images, I can usually hear them and often find it painful to be near just because of how high pitched it is. I'm not sure what it is that is in old monitors that cause this noise, but I notice it virtually every time i am anywhere near one. Very few are inaudible to my ears. Power supplies that i notice buzz usually are much lower pitched than this so are not painful, just very irritating. Just seems so difficult to find the sort that I'm after that is fully enclosed. I think I will just keep a look out for old equipment getting thrown out that still has a proper 12v power supply by a good brand - which often are not sold separately. It is strange just how variable the noise of these things can be. I've been through a lot of power supplies by Netgear for network switches, some of which have been almost silent and others have made a high pitched squeak the second they get plugged in, even without any load on them. This is sometimes the case even if the design and label looks identical. The main problem is that when I dim LED strips, the power supply almost always gets louder apart from on the good ones. The only use I will have for these will be for LEDs or audio systems. With audio, any noise from the supply gets fed through the amplifier to the speakers and then amplifying it obviously makes it worse.


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## DIWdiver (Mar 14, 2020)

I had a problem years ago where the forum wouldn't acknowledge when I pressed the enter key. I used to open notepad, copy a carriage return to the clipboard, then paste it when I needed to. Eventually I found out that it was a combination of the software used to host the forum and Internet Explorer. I switched to Chrome, and haven't had the problem since.

The reason some power supplies are heavy is that they use a laminated steel core transformer that operates at line frequency (50 or 60 Hz, depending on where you are), while the lighter ones use a high frequency transformer that can be MUCH smaller and lighter for a given power level. Line frequency transformers are usually coupled with linear regulators, and are dead silent unless there's something loose in the transformer, which can buzz at 50 or 60 Hz. There's lots of harmonic content to this noise, but even the 30th harmonic of 60 Hz is only 1800 Hz.


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## JustAnOldFashionedLEDGuy (Apr 13, 2020)

DIWdiver said:


> It sounds like what you need is an old-fashioned linear supply with electrolytic caps. Most modern supplies are switchers, (including the ones you linked) because they've gotten cheaper to build than linears.
> 
> While the switching frequencies are almost always well above the audio range (50 kHz would be quite low, some are over 1 MHz), the PWM frequencies are usually right in the audio band, 200-5000 Hz. Ceramic caps that are so popular now can have a piezoelectric effect, where they change shape with applied voltage. Inductors can have electromagnetically induced mechanical motion as well. I once designed an LED driver that had to have the caps switched from ceramic to more expensive electrolytic ones to eliminate the whine from the caps.
> 
> ...




Virtually every 12V AC\DC power supply you will find out there will have electrolytic capacitors on the output. Odds are there will not even be any ceramic capacitors on the output as that would be added cost. Some of the 12V PWM dimmers will have ceramic caps in them that can be noisy. In the supply, it will typically be mechanical noise in output EMI inductors, 2nd-stage power conversion inductors/transformers, and the primary transformer as the PWM frequency directly modulates these components.


In cheap supplies, there will be some silicone to keep the big capacitors from shaking off during shipping and usage. In good quality expensive supplies, the unit will be filled with potting compound (silicone, tar, soft epoxy, soft urethane) that makes a great noise suppressor. When shopping, look at the weight of the driver compared to the volume. If it appears heavy for the volume, it may be potted.


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## JustAnOldFashionedLEDGuy (Apr 13, 2020)

Deleting ... duplicate.


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## HarryN (Apr 15, 2020)

The good and bad about LED drivers and power supplies getting cheaper is that cost is the over riding factor.

The local restaurants are using LED fixed lighting fixtures that emit enough RF to affect cell phone reception.

I do some work in battery backed auxiliary power systems. Now when I want a quiet 12 volt source I just use a good AGM marine battery.

You might have some success with a linear power supply. Acopian makes some very decent ones.

Don't go to places like ebay and amazon for high quality electronics. Look for commercial distributors like mouser, newark, element14, farnell, allied.

If you purchase a commercial power supply that is rated at 3-5x your need, then the internal cooling fans usually won't turn on, reducing noise.


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## DIWdiver (Apr 15, 2020)

JustAnOldFashionedLEDGuy said:


> Virtually every 12V AC\DC power supply you will find out there will have electrolytic capacitors on the output. Odds are there will not even be any ceramic capacitors on the output as that would be added cost. ]
> 
> This might have been true years ago, but with modern high-frequency switchers, the capacitances required are so much smaller that ceramics often are the cheaper choice, especially in lower current applications (which definition is rapidly evolving). As I mentioned, we changed the design from ceramic to MORE EXPENSIVE electrolytic caps to eliminate noise. As I recall, we went from something like 3x 10 uF ceramic to 2x 680 uF high-ripple electrolytics, because of the ripple current requirements.
> 
> ...


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## JustAnOldFashionedLEDGuy (Apr 16, 2020)

> This might have been true years ago, but with modern high-frequency switchers, the capacitances required are so much smaller that ceramics often are the cheaper choice, especially in lower current applications (which definition is rapidly evolving). As I mentioned, we changed the design from ceramic to MORE EXPENSIVE electrolytic caps to eliminate noise. As I recall, we went from something like 3x 10 uF ceramic to 2x 680 uF high-ripple electrolytics, because of the ripple current requirements.
> 
> I design many switching regulators in the 2A or less range, and haven't used electolytic caps on the outputs for many years, mostly for cost reasons, though size also is a factor sometimes.
> 
> I'm not saying that electrolytic caps don't have a place in modern supplies, even as output caps. As power output goes up and (often because of this) as switching frequency goes down electrolytics get more attractive.




This is simply, and not remotely the case for AC\DC power supplies (which is what we are talking about here and what I referenced). I would be surprised if even 0.1% by volume of AC\DC power supplies use ceramic or film capacitors as their primary output capacitors. Take any high volume AC\DC application: Laptop power supplies, Desktop power supplies, Cellphone \ USB chargers, LED Drivers, Television \ Consumer electronics power supplies .... every one of them will be using electrolytic output capacitors on the output, perhaps with small ceramic capacitors for EMI improvement. About the only place you see any volume in ceramic\film for AC\DC power supplies is in low power module level supplies for appliances and often they call for external electrolytic capacitors to be added, some high performance board-mount modules for servers, and some costly miniaturized aftermarket supplies for laptops using high-frequency (by AC\DC standards) multi-stage architectures (but often they have electrolytics in parallel for bulk storage).


The 12V AC\DC the op is using is going to have electrolytic output capacitors as would almost virtually every other power supply similar to it, and everyone he is likely to consider replacing it with.


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## TheGiantHogweed (Apr 18, 2020)

The thing that I notice is that if the power supply makes audible noise, my PWM dimmer makes the same when dimmed. Where as if the power supply makes no or little audible noise, that is the same for the dimmer switch for the LED strip. At least is in my case. But no matter if the power supply is potted as you say, if it actually has noisy components inside that can't be heard from the brick itself, I guess it still will be audible from a dimmer switch. All power supplies I have make the dimmer make a slight noise, but the best ones only are audible if you put your ear right next to the transformer or dimmer when it is dimmed. I'll just keep a look out for 12 supplies that come with old proper branded devices as these are usually very quiet (and heavy) and not sold separately.


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## TheGiantHogweed (Apr 19, 2020)

I may as well also ask this here. I have 3 long LED strips in my garage at home. 3x2.5m. The strips are 2 LEDs wide and claim to use 24 watts per metre which I think is pretty accurate, despite them being cheap. If you don't take into account that the strips probably lose a bit of power over their length, then all these 3 strips added together would use 180w. So I have been using them with a 12v 15A power supply with some 12v cable rated for up to 16A. The cable does actually get every so slightly warm when they have been on for over an hour, which probably suggests the LED strips do use close to what they claim, as this will also be close to the maximum rating of the cable. I split it at a junction box to go to each of the strips and it has done a great job for several years. This is the sort of supply I was using. Cheap and pretty noisy, but seemed to do the job fine: https://www.ebay.co.uk/itm/DC-12V-2...hash=item23cc890434:m:mHqNIDN_LOCdsDDQjIxDlVA

Because of the location, I didn't really care about the noise, but it is nor making some more concerning sounds and I'm not sure if this is a sign it is on its way out. whenever the lights are switched off by a switch on the cable, the transformer makes some pretty loud and inconsistent clicks. It does this permanently unless you turn of the mains input. Doing this stops the clicks when you turn the power back on for a while, but soon after the lights have been used then switched off, it does it again. It never does this when the lights are on, and the LEDs work fine and don't flicker. The power supply also only gets moderately warm when in use. If this sound could indicate there is an issue with it, i should probably get a replacement. But I think I should spend a bit more. Probably up to £25 - £30.

Any suggestions?

Thanks.


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## JustAnOldFashionedLEDGuy (Apr 19, 2020)

To the op, I guarantee if you put a few thousand uf of high quality capacitance on the output of your noisy supplies the noise will drop significantly. Make sure they are good capacitors designed for switch mode power supplies. And inductor and capacitor would be ideal but the inductor needs to be of proper construction so it does not make noise.


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## JustAnOldFashionedLEDGuy (Apr 19, 2020)

Hogweed, some power supplies are not designed to operate at 0 load. Others will, but they may have burst modes that essentially turn on/off the supply that sounds like clicks. If not designed for 0 load the output voltage likely creeps up with no load till protection is triggered. It will go through on-protection-off-on cycles say every 100 msec and click when it comes back on. That click is mechanical noise for the transformer.


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## TheGiantHogweed (Apr 21, 2020)

The power supply I got may have been cheap, but it did specifically say it was suitable for LED strips. I would assume that in many situations, they would not be turned on the whole time. The clicks the supply has started making when switched off is quite inconsistent. i would probably say averages out, there is a click every half second or so, but they are sometimes quiet, sometimes not. It is certainly true that most of the time, the power supply will be on and the LEDs will be off by a switch on the cable, so no load will be being used. If this clicking isn't a problem, I can probably keep what I have for now. If it could be an issue, I should probably get some sort of power supply that can remain powered on the whole time, but also allow the load to be on or fully off.


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## HarryN (Apr 22, 2020)

12 volt chargers are fairly inexpensive, as are AGM batteries. For $500 you can have a set up that can run LED strips and have light even when the grid fails. For an extra $300 you can run it off of a solar panel. Very quiet.


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## TheGiantHogweed (Jun 10, 2020)

JustAnOldFashionedLEDGuy said:


> Hogweed, some power supplies are not designed to operate at 0 load. Others will, but they may have burst modes that essentially turn on/off the supply that sounds like clicks. If not designed for 0 load the output voltage likely creeps up with no load till protection is triggered. It will go through on-protection-off-on cycles say every 100 msec and click when it comes back on. That click is mechanical noise for the transformer.




Well, the noise from this has remained the same while turned off. But just a few days ago, it has given up totally. If your advice could be that it maybe isn't designed to permanently have power running to it, but have the transformer under no load a lot of the time, that may explain it. I had the switch for the lights on the 12v cable and they were off most of the time, but the supply continuously running. I've now set it up so that the switch will on the mains cable going to the power supply so it then no power will be staying in the transformer.

I've ended up going for this one: https://www.amazon.co.uk/dp/B07ZJ154DZ/

It is about double the price of the one that has given up and has a fan in so may help with cooling. According to the specs of the LEDs, they will use 180w if i base it on the length, so this should be fine. It also has a fan in which will help cooling. In this case, I'm not as bothered about noise as it is in the garage.


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