I just calculated this at minimum and maximum mains voltages and it is not shocking. "Burning away a lot of voltage" is slightly exaggerated. We are talking 10W power supplies here so let's say 5V @2A max. I used a 6V transformer for this but I could do with a 5V one as I have done in the past with LDO regs. Even less dissipation. The challenge here is to use the right transformer for the right output voltage in both circumstances. Still with ultra low drop regs -15% is not a problem. For 5V 2A I don't see a boatload of caps needed.....Dissipation is higher than with SMPS but we are in audio land, we want best quality and do not shy away from burning some Watts if quality is key parameter.
A tube guy drops tens of Watts with resistors (besides the tubes themselves keeping the kWh meter running) and he does not sleep less well at night
We are running in circles. No one was mentioning compact being of utmost importance. If so we can quit linear power supplies altogether. They wil never be as small as SMPS as linear PSU's need a chunk of iron and meters copper wire. Not a true criterium if the device is a standard 19" device. I thought we were discussing technical features (so electrical properties being key parameters) in our quest for good power supplies be it linear or SMPS.
Rcores have very low magnetic strayfields and can be mounted very very close to sensitive circuits. in fact I did not believe what I saw when I tried it out. I wish I could've bought these when I started this hobby as they are very good. SMPS may be friendly regarding magnetic fields but you get EMI in return. Rcores do not emit EMI or RF garbage. As we say here: it is trading lead for old iron
BTW if SMPS is a Switched Mode Power Supply then a linear PSU is a LMPS ?!
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If you pick a quality SMPS, especially with a high switching frequency you can easily filter it. It's a lot easier to shield against EMI / RF than low frequency magnetic fields as well.
The concerns over transformer placement are real in devices like DACs and preamps, which you might not want to have a huge chassis for. Audible hum is probably not hard to avoid, but some of us don't want anything measurable either.
Also for vertically stacked components it can be an issue.
The concerns over transformer placement are real in devices like DACs and preamps, which you might not want to have a huge chassis for. Audible hum is probably not hard to avoid, but some of us don't want anything measurable either.
Also for vertically stacked components it can be an issue.
Please define quality. Many SMPS that I got with equipment are utter garbage. Where to find a suitable wall wart SMPS replacement with better properties for audio ? A low power, so under 10W, SMPS that is. Chances are high that I find one that is equally mediocre compared to the old one. Chances are high that I have success with a linear PSU.
I get your point about measurements but I already pointed out that there are excellent transformers nowadays (at the end of the transformer era). If transformers are such a big problem why do manufacturers still choose transformers in their high end stuff ? SMPS are cheaper and lighter etc. yet they use transformers and deliver hum free audio.
If some of us do't want anything measurable they should also care for EMI problems with SMPS. Audible noise coming from SMPS...
I get your point about measurements but I already pointed out that there are excellent transformers nowadays (at the end of the transformer era). If transformers are such a big problem why do manufacturers still choose transformers in their high end stuff ? SMPS are cheaper and lighter etc. yet they use transformers and deliver hum free audio.
If some of us do't want anything measurable they should also care for EMI problems with SMPS. Audible noise coming from SMPS...
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What ??! For low power in 99% of cases a regulator IC is used. You exaggerate somewhat. I have yet to see a PSU for low power electronics with a classic linear PSU without regulation. Often the electronics are at risk without regulation. As always: the cleaner the PSU the better.
Back to the subject: we apparently need a true audiophile quality mains fed PSU of max. 10VA (adjustable voltage), single or dual output with small dimensions and the possibility to use it either as an adapter in the "wall wart " fashion for those that like that and the possibility to use it directly in a device so mounting holes and pads for an IEC connector. Sturdy PCB design, tested quality and none of the negative things that seem to surround current ready made SMPSes. An SMPS designed for "best of class" performance and not low cost. True harmony with the other audio equipment one has.
Design goals:
- high reliability
- designed for longevity
- fail safe operation
- designed for "always on" operation
- ultra low EMI
- high efficiency
- ultra low ripple
- single or dual output
- configurable from 3.3 to 24V 10VA without compromising on quality, if needed different versions.
- nice load for the grid so no mains pollution
- Use with either plastic wall wart case or integrated in a device
- compact size
Who takes the challenge ?
Although you mention a lot of requirements, they are not complete for a commercial design.
What is about CE-marking? Without, you can't sell it in EU (or elsewhere)
To comply, you have to consider other aspects:
-Always on: What is about (standby-) power consumption and efficiency - actually DoE-level V is mandatory in EU, level VI in US. You cannot comply to these Eco-levels with a linear transformer - it is just impossible, period!
I would not go for anything like a wall wart. Restricted to 2prong plugs, there is no way to access PE-terminal which can be used otherwise as functional earth to ground EM-noise.
The lack of PE connection is a main reason for the exceptional noisy behaviour of this type of power supply.
Better consider a ac-adapter with 3 wire cable.
An adjustable switchmode supply is a challenge in itself.
You could go for flyback, which is the the cheapest solution.
With the drawback of high EM-emissions.
You could go for push-pull - bad regulation over wide output voltage. Or phase shifted zero voltage full bridge - quite a complex design normally preferred for several hundred watts output power.
btw, for your application I would propose an LLC-converter with synchronous rectification.
The pros are:
-very high efficiency , expect something close to 93%
-low parts stress, low ripple current in secondary caps
-low em-noise
-quite stable output voltage even without regulation
-tiny ferrite transformer, compared to flyback solution
-extreme low primary - secondary coupling capacitance due to sectional transformer windings -> low common mode noise
Some years ago I designed such a LLC-converter with 13W output capability which proved quite successful.
The pros are:
-very high efficiency , expect something close to 93%
-low parts stress, low ripple current in secondary caps
-low em-noise
-quite stable output voltage even without regulation
-tiny ferrite transformer, compared to flyback solution
-extreme low primary - secondary coupling capacitance due to sectional transformer windings -> low common mode noise
Some years ago I designed such a LLC-converter with 13W output capability which proved quite successful.
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Please show your design !
This is DIY, not commercial. CE is not a DIY requirement. Cheapest is no requirement, the cheapest was already delivered with your new DAC. Although it would be nice if it follows DoE-level V I think many could care less for audio. When looking at the people that are busy with audio I guess being non compliant means no real danger to the environment. Throwing defective or polluting SMPS in the landfill is worse for the environment. If we want to be holier than the pope then DIY tube amps and class A amps should be banned. High EM emissions is a big no no as that is why an audiophile version is wanted isn't it ? PE connection is mandatory indeed (which rules out non PE wall wart types although PE types exist but they are uncommon).
Again, if you look at it from various angles you wil see that is nearly impossible to make an DIY audiophile SMPS for under 10W. There is a reason even all A brands buy chinese cheap SMPS as its all about the numbers. I will stick to my own design LDO. In theory all kinds of different technical superior systems exist for SMPS but in practice many are below the quality level I would like to see in audio. There was a reason I replace them for linear PSU's ! Many people in DIY do the same, why would that be if SMPS are good ? Just replacing them to have something to do ?
For those that arre unfamiliar with DoE-level V: http://www.cui.com/catalog/resource...ncy-standards-for-external-power-supplies.pdf
This is DIY, not commercial. CE is not a DIY requirement. Cheapest is no requirement, the cheapest was already delivered with your new DAC
. Although it would be nice if it follows DoE-level V I think many could care less for audio. When looking at the people that are busy with audio I guess being non compliant means no real danger to the environment. Throwing defective or polluting SMPS in the landfill is worse for the environment. If we want to be holier than the pope then DIY tube amps and class A amps should be banned. High EM emissions is a big no no as that is why an audiophile version is wanted isn't it ? PE connection is mandatory indeed (which rules out non PE wall wart types although PE types exist but they are uncommon).Again, if you look at it from various angles you wil see that is nearly impossible to make an DIY audiophile SMPS for under 10W. There is a reason even all A brands buy chinese cheap SMPS as its all about the numbers. I will stick to my own design LDO. In theory all kinds of different technical superior systems exist for SMPS but in practice many are below the quality level I would like to see in audio. There was a reason I replace them for linear PSU's ! Many people in DIY do the same, why would that be if SMPS are good ? Just replacing them to have something to do ?
For those that arre unfamiliar with DoE-level V: http://www.cui.com/catalog/resource...ncy-standards-for-external-power-supplies.pdf
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It's only nearly impossible if you want to do it from a to z (and I fail to see the point of that). If you're willing to mix ready-made parts and additional filtering, I don't see any reason why a small smps based design would be any inferior to a linear one.
The shortcomings of commercial designs are irrelevant here.
You don't see a reason an SMPS should be inferior to a linear PSU. This implies a linear PSU to be the best option Which it is for low power. It is too expensive though. It contains iron and copper and it is heavy. It is non eco (not many leave equipment switched on in contrary to wall warts that are powered on for years). That is why you get such a tedious external adapter with most of your audio stuff. It is cheap and the factory that produces them in very large numbers had it tested along all eco and other requirements. It was not certified for longevity or audiophile qualities. It takes away the burden of testing and certifying so cheapest solution for many audio brands is to add an external OEM adapter. Nobody in the design department stood up and said: let's make the best SMPS in our new device ! There were a few that thought this but it is about making profit in these harsh times for audio companies.
Even throwing together and make a mix of ready made cheap stuff on a new PCB with extra filtering can not be as simple, cheap and performing as a well designed LDO. There must be some truth in this as I don't see many DIY SMPS and also no DIY/commercial mix SMPS. I do see an army of commercial enterprises making audiophile linear PSU's as replacements for our friend the SMPS.
As we see even the best switcher needs one of the best current (linear so old fashioned) LDO chips for audiophile qualities. So tell me please what is the benefit of replacing the transformer- bridge-cap combo for a polluting circuit that needs many requirements we can't fulfil in DIY ? The same LDO's can be used with the classical combo and it can be tuned for lowest losses/heat. Even if you loose some Watts in heat you won't leave the PSU switched on in contrary to wall warts that are plugged in forever. In the long run that is no real difference. Using a linear PSU will require a real mains switch which is also too expensive and customers can't switch on the device with their remote, well they can but then you will need a second PSU for the standby function...
After 10+ years you will still be using the same linear PSU while the switcher was thrown away as it suddenly stopped working and had bulging caps
Which it is for low power. It is too expensive though. It contains iron and copper and it is heavy. It is non eco (not many leave equipment switched on in contrary to wall warts that are powered on for years). That is why you get such a tedious external adapter with most of your audio stuff. It is cheap and the factory that produces them in very large numbers had it tested along all eco and other requirements. It was not certified for longevity or audiophile qualities. It takes away the burden of testing and certifying so cheapest solution for many audio brands is to add an external OEM adapter. Nobody in the design department stood up and said: let's make the best SMPS in our new device ! There were a few that thought this but it is about making profit in these harsh times for audio companies.Even throwing together and make a mix of ready made cheap stuff on a new PCB with extra filtering can not be as simple, cheap and performing as a well designed LDO. There must be some truth in this as I don't see many DIY SMPS and also no DIY/commercial mix SMPS. I do see an army of commercial enterprises making audiophile linear PSU's as replacements for our friend the SMPS.
As we see even the best switcher needs one of the best current (linear so old fashioned
) LDO chips for audiophile qualities. So tell me please what is the benefit of replacing the transformer- bridge-cap combo for a polluting circuit that needs many requirements we can't fulfil in DIY ? The same LDO's can be used with the classical combo and it can be tuned for lowest losses/heat. Even if you loose some Watts in heat you won't leave the PSU switched on in contrary to wall warts that are plugged in forever. In the long run that is no real difference. Using a linear PSU will require a real mains switch which is also too expensive and customers can't switch on the device with their remote, well they can but then you will need a second PSU for the standby function...After 10+ years you will still be using the same linear PSU while the switcher was thrown away as it suddenly stopped working and had bulging caps
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Not inferior means either better or equal. So no, it doesn't imply the linear being better, it just recognize the linear as the usual standard.
The wallwart argument doesn't hold. Linear wallwarts were left powered too for years on. For diy, nobody forces you to use an external wallwart anyway.
Actually throwing a mix of ready made modules and filtering can be as cheap and good performing as a LDO (since we'll stick an ldo at the end anyway). It might be a bit more complex. The valid comparaison isn't smps vs a whole linear supply (from iec to regulator) but smps vs the xformer-diode-caps part of your linear supply. Nothing can match the performances of modern linear LDOs, that's a given.
The transformer bridge cap combo can be just as polluting as an smps as already pointed, especially when space is at a premium. And the smps pollution can be dealt with, unlike a xformer where the only solution is space. And because you don't value small size, lowest dissipation (even a pair of watts can be too much in a small sealed enclosure) and power consumption doesn't mean others don't.
And the many requirements you can't fulfill in diy are only impossible to fulfill if you insist again on doing it all yourself.
The wallwart argument doesn't hold. Linear wallwarts were left powered too for years on. For diy, nobody forces you to use an external wallwart anyway.
Actually throwing a mix of ready made modules and filtering can be as cheap and good performing as a LDO (since we'll stick an ldo at the end anyway). It might be a bit more complex. The valid comparaison isn't smps vs a whole linear supply (from iec to regulator) but smps vs the xformer-diode-caps part of your linear supply. Nothing can match the performances of modern linear LDOs, that's a given.
The transformer bridge cap combo can be just as polluting as an smps as already pointed, especially when space is at a premium. And the smps pollution can be dealt with, unlike a xformer where the only solution is space. And because you don't value small size, lowest dissipation (even a pair of watts can be too much in a small sealed enclosure) and power consumption doesn't mean others don't.
And the many requirements you can't fulfill in diy are only impossible to fulfill if you insist again on doing it all yourself.
If the problem is the charging for the power bank, you can make your own.
Separate chassis, batteries and charger included, mains connected.
When you use your audio equipment, the batteries will be disconnected from the charger and feeding the silent switcher. When your equipment will be off the batteries will be charging again...and so on...
Separate chassis, batteries and charger included, mains connected.
When you use your audio equipment, the batteries will be disconnected from the charger and feeding the silent switcher. When your equipment will be off the batteries will be charging again...and so on...
We really are running in circles. I tried to make my point and have spent to many words already. Be it internal or external power supplies, for low power almost no DIYer builds or buys SMPS. On the contrary, low power SMPS are replaced for linear PSU's. I never see people doing the opposite with low power devices
- For ready made equipment that have an external low power SMPS PSU a better external audiophile quality SMPS should exist. It does not.
- For ready made equipment that have an internal SMPS an better audiophile SMPS should exist: there are not many audiophile quality low power SMPS for internal use.
- For DIY equipment all freedom is there to make it as small or as large as one wants. Be it linear or SMPS, many DIYers will choose linear
Personally I do value small size and build my stuff as small and green as possible (even at the near level of fundamentalism) and managed to keep it linear till now with no excessive heat. Even if one would loose the full power of the PSU in heat it still is only 10W per device. I don't trade in quality for price when DIYing. If it costs a bit more energy at an audiophile benefit I will choose the better solution for audio. The equipment will only be used for a few hours a day. Maybe it helps if you know I work(ed) in a very energy consuming industry and my special interest goes to making processes greener. In one project I managed to save 110,000 kWh a month and last year I managed to save 48,000 kWh a month. That are IMO numbers that count. Loosing 2W in heat when choosing a linear PSU for a Squeezebox Touch or a DAC that are used 1 hour a day does not count enough to make a true difference.
THE selling point of low power SMPS is price. No more no less.
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If the problem is the charging for the power bank, you can make your own.
Separate chassis, batteries and charger included, mains connected.
When you use your audio equipment, the batteries will be disconnected from the charger and feeding the silent switcher. When your equipment will be off the batteries will be charging again...and so on...
You choose the difficult path but good thinking. For me a bridge too far with added hassle. Might be a good solution for those that desperately need mains isolated audio. The thread is not just about the Silentswitcher but that one is a good combination of factors. The Powerbank charging and switching unit could as well be integrated in a device together wth the Silentswitcher. Powerbank and charging/switching parts operated by switches and possibly some logic stuff switching the charging circuit completely off while using the equipment. No external stuff dangling around, it certainly has some virtues: user friendliness, simple one button operation, mains isolated audio, no cabling and no possibility for a suddenly lost powerbank. Can be made inexpensive with a transformer that has its primaries switched off when listening. Sorry slip of the tongue, it can be done with a low power SMPS with 230V side switched off when listening. True eco !
So we need to convince Jan to design an audiophile Powerbank charging and switching circuit ?!
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That was the idea, be it Silentswitcher or whatever.
I have seen a lot of designs here of floating power supplies trying to isolate from mains.
This would useful for testing equipment also.
And for extreme diy, off topic of course, massive batteries for power amps. There are allready descent SMPS for power amps
You asked for some information about my LLC-proceedings
Until now I built 15W LLC converters with 24 or 40V dc input.
These could be adapted, i.e. redesigned to 230V ac input.
Admittedly this project waits for some finalisation
Attached is a working circuit diagramm and a pic of an early stage breadboard showing the size of transformer.
This discussion shows a range of different design goals - so let me explain mine
- lowest EM emission
- lowest leakage current
- lowest component stress for long life
- highest efficiency
- as simple as possible, i.e. unregulated
This type of converter is a direct replacement for an unregulated linear transformer supply, including its 100Hz ripple.
Extreme low output ripple is not the goal, this can be achieved with additional LDO.
At this time, I do not have a 230V/15W Version done, but it is in my pipeline.
Until now I built 15W LLC converters with 24 or 40V dc input.
These could be adapted, i.e. redesigned to 230V ac input.
Admittedly this project waits for some finalisation
Attached is a working circuit diagramm and a pic of an early stage breadboard showing the size of transformer.
This discussion shows a range of different design goals - so let me explain mine
- lowest EM emission
- lowest leakage current
- lowest component stress for long life
- highest efficiency
- as simple as possible, i.e. unregulated
This type of converter is a direct replacement for an unregulated linear transformer supply, including its 100Hz ripple.
Extreme low output ripple is not the goal, this can be achieved with additional LDO.
At this time, I do not have a 230V/15W Version done, but it is in my pipeline.
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That is still a way to go but I think many will appreciate it if you start a thread about a 15W 230V mains fed version. You will make headlines here on diyaudio.com being the first with an audiophile low power SMPS for DIY.
Reading back my posts I think my presence is a tad too much in this thread. Good luck to all, enjoy your devices with either linear PSU or SMPS !
Reading back my posts I think my presence is a tad too much in this thread. Good luck to all, enjoy your devices with either linear PSU or SMPS !
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That would be a grey zone as class A amps and their PSU's + mains connections are discussed openly. "All animals are equal but some animals are more equal than others"
Just looked it up and it says:
While most projects on this site deal with electricity and construction which inherently involve some risk, particularly dangerous topics and procedures should include a warning in the thread that adequately explains these risks. Certain inherently dangerous topics are not allowed. At this time they include but are not limited to: discussing power supplies directly fed by mains current without a transformer, and mucking about in CRT video monitors. Posts and projects are those of individual members of diyAudio. The forum itself is not in the business of vetting projects or posts for safety, accuracy, performance, reliability, function, or fitness for use. If you attempt to make something and it blows up, or turns expensive parts into charcoal, or just doesn't work the way you were hoping, that's between you and the person posting the project or idea. The forum is merely a bulletin board which allows anyone to post ideas, criticisms, or discussions. It is up to the individual to make the final determination of how appropriate a project is for them to attempt, based on their own experience.
Mmm, this would indeed rule out DIY mains fed SMPS. Problem solved !
Just looked it up and it says:
While most projects on this site deal with electricity and construction which inherently involve some risk, particularly dangerous topics and procedures should include a warning in the thread that adequately explains these risks. Certain inherently dangerous topics are not allowed. At this time they include but are not limited to: discussing power supplies directly fed by mains current without a transformer, and mucking about in CRT video monitors. Posts and projects are those of individual members of diyAudio. The forum itself is not in the business of vetting projects or posts for safety, accuracy, performance, reliability, function, or fitness for use. If you attempt to make something and it blows up, or turns expensive parts into charcoal, or just doesn't work the way you were hoping, that's between you and the person posting the project or idea. The forum is merely a bulletin board which allows anyone to post ideas, criticisms, or discussions. It is up to the individual to make the final determination of how appropriate a project is for them to attempt, based on their own experience.
Mmm, this would indeed rule out DIY mains fed SMPS. Problem solved !
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