My Behringer active rackmount equalizer that uses an internal toroidal mains transformer and linear-regulated PSU board isn't UL certified and they're a billion dollar multinational company. But the design is textbook.
d to find lowest cost. Even at low volumes, it pays to do a custom design
PC
the
more, or the external supply you use can supply more
ocess is pretty much the same as approving your own custom supply. And the cost for the approval is not that high, complete product might be 15k USD f or an advanced product with several insulation systems
ncidence have an idea to only approve components/parts that is not part of the IEC system, so that one is forced to make both US and EU variants
st
Meanwell and competitor supplies, you find that they really are not that g ood. We did an internal products, just me and another guy, and in 12 months we had a solution that outprformed the Meanwell types in price and perform ance.
magnitude better (sub 90% efficiency is a joke, cannot see why do would sel l such bad products)
I have the luxury of having a a lot of high volume parts running in current products (many more than 20 mill pcs per year), so I can cherry pick the l ow cost ones and use in this supply
For the custom part, you can do tricks on the pricing of the common mode in ductors and transformers that will shock you. Those 2 parts are the most ex pensive parts in the construction. But it means you have to divert away fro m your COTS magnetics, and you do not seem to like that. You should reconsi der, the price is a different ballgame when you go into deep dialogue with the manufactor
Also you can do tricks that can remove certain parts that one would normall y use, but I cannot disclose those details here for IP reasons
When you are talking about magnitudes in efficiency and your are above 95%, any 1% increase is really a monumental effort and takes real creative engi neering
Cheers
Klaus
That is dangerous
In CE you can ship the product, if you are sure you comply with the regulations
Trouble is, if they ask for the test results, you must be able to provide them with days of leadtime
Cheers
Klaus
That is really a betting game. If they have a person injured, they could be out of business from the lawsuit
Specify, buy and use them. Or is the specification stage above your pay gra de?
The filtering is between the output of the supply and device it is powering .
Some power supplies do have the nasty habit of spitting high frequency curr ent into every earth connection they can get at, and blocking that can take an effort.
There are commercial off-shelf-devices that are better behaved, and corresp ondingly easier to tame.
If you don't care what you buy, or at the mercy of a buying department who can buy anything they like as long as it is cheap and doesn't actually let it's output move far out of tolerance to be actually destructive the job be comes rather more demanding.
Your original claim was that " We had some very noise sensitive devices th at we were only able to power with linear supplies."
You had enough control over what you used to reject switching power supplie s. If you'd had a better grasp of what you were doing you could have reject ed the noisier switching power supplies. You do seem to lack the kind of de sign skills that would let you filter the power rails at the noise sensitiv e device you were hanging off them.
Some people have been known to put little local linear regulators at the se nsitive device - that wastes a bit of power but can give you a lot of rail noise rejection at low frequencies where passive filtering devices get a bi t bulky.
But that's a design choice, not am absolute requirement.
-- Bill Sloman, Sydney
LinkSwitch.
Tim
-- Seven Transistor Labs, LLC Electrical Engineering Consultation and Design Website: https://www.seventransistorlabs.com/
Don't buy from Power Integrations. They have dubious sales techniquies and the products from OnSemi and Diodes are better
Use NCP10670 for example
I agree, it's a shame when high-power supplies have poor efficiencies. I recently purchased a 48-volt 600W Meanwell supply, recommended for use with a highly-engineered Chinese regulator found on Alibaba. :-) SE-600-48, only $72 on Amazon, with free shipping. Same unit as JL?
Its efficiency spec is 88%. If I were to use it 24-7 at 300W, its extra 7% loss compared to a 95% unit, amounts to an extra 920 kWh over 5 years. At our 20-cent/kWh rate in NE, that'd cost us an extra $184 for electricity, dramatically wiping out any savings. {Its actual use will only be occasional, on the bench.}
However, I think its 88% efficiency spec is for 600W full power. Surely it'll be better at normal operating levels? But it's clearly a very old design, still being cranked out in volume. For example, the mains voltage is selected by a switch (!). I won't be flyback, at 600W, but there's also no mention of PFC. And its 2019 datasheet says, do not use within the EU. Haha.
--
Thanks,
- Win
Bill Sloman wrote in news: snipped-for-privacy@googlegroups.com:
Yep. That is what we decided to use. With millions of dollars being invested by the DoD, we do what they tell us to do. We engineer into the system the proven circuits they want used.
When on makes a 1024 channel stimulator where all of them are synched to within a nanosecond of each other, one wants repeatability and cost effectiveness and precision. Doing that across 16 racks of gear takes real engineering, not some dork spouting off basic, fully understood bullshit about how to filter a supply rail.
Design choices were 100% our engineering group's scope. Us and the DoD.
You are an unintelligent asshole, at best.
The presumptuous pussy, Billy Sloman cannot go a single post without insulting folks and he can't even get that right.
We rejected switchers altogether for that application, you stupid f*ck! You seem to have a problem with that choice. Sorry, PUTZ, but you are the idiot.
Bill Sloman, being a Doanld J. Trumplike utter retard yet agin.
If you can make a 600 watt offline PFC switcher, in a metal box, for $6, why aren't you selling them on Digikey?
-- John Larkin Highland Technology, Inc lunatic fringe electronics
Here's some pics of a similar MeanWell supply.
It's potted, presumably for heat transfer, since this on is very small and has no fan. I tested it in free still air, but it's meant to be conduction cooled. My degc/w numbers are actually watts/degc.
Output regulation was perfect, to four digits.
For my product, I'll use a bigger one, 800 watts, which includes a fan.
-- John Larkin Highland Technology, Inc lunatic fringe electronics
I designed 5 or 6 NMR gradient amps, sold OEM to Agilent. They paid to have them fully lab certified to UL and CE and everything. None were destroyed, and we had no follow-up inspections of any kind.
We had to make a few small tweaks, like wire colors and stuff, but didn't have to re-test.
I recently self-certified one of our boxes to CE for a customer who needed it in a system. He never asked to see the cert report, or even the signed certificate of conformance. All he wanted was the sticker.
It's not awful to self-certify to CE. You can farm out just the EMI part if you don't have the equipment. The biggest hassle is figuring out which specs apply, and getting those specs.
If CE is mandatory, why are the specs so expensive?
-- John Larkin Highland Technology, Inc lunatic fringe electronics
But does that happen? And what if you ignore the request?
-- John Larkin Highland Technology, Inc lunatic fringe electronics
I have only seen it once, in an earlier company I worked for, we were asked to provide the information. Luckily we had it all done, so could just send it out
If you can't, I do not know exactly what kind of re-enforcement of the rules they have. I think you can be told to return all units
Just did a search:
Seems there are examples of prosecution of non compliance
d to find lowest cost. Even at low volumes, it pays to do a custom design
PC
the
more, or the external supply you use can supply more
ocess is pretty much the same as approving your own custom supply. And the cost for the approval is not that high, complete product might be 15k USD f or an advanced product with several insulation systems
ncidence have an idea to only approve components/parts that is not part of the IEC system, so that one is forced to make both US and EU variants
st
Meanwell and competitor supplies, you find that they really are not that g ood. We did an internal products, just me and another guy, and in 12 months we had a solution that outprformed the Meanwell types in price and perform ance.
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design, which is a bad move
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Great, thanks a lot
From the datasheet, it has PFC like expected. Not really possible to see wh at kind of converter it is, but looks like a 2 switch flyback or a push pul l from the 2 FETs on the bottom cooling plate
Cheers
Klaus
in
need to find lowest cost. Even at low volumes, it pays to do a custom desig n
my PC
gn
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is
ws more, or the external supply you use can supply more
process is pretty much the same as approving your own custom supply. And t he cost for the approval is not that high, complete product might be 15k US D for an advanced product with several insulation systems
coincidence have an idea to only approve components/parts that is not part of the IEC system, so that one is forced to make both US and EU variants
cost
the Meanwell and competitor supplies, you find that they really are not tha t good. We did an internal products, just me and another guy, and in 12 mon ths we had a solution that outprformed the Meanwell types in price and perf ormance.
dof magnitude better (sub 90% efficiency is a joke, cannot see why do would sell such bad products)
ent products (many more than 20 mill pcs per year), so I can cherry pick th e low cost ones and use in this supply
inductors and transformers that will shock you. Those 2 parts are the most expensive parts in the construction. But it means you have to divert away from your COTS magnetics, and you do not seem to like that. You should reco nsider, the price is a different ballgame when you go into deep dialogue wi th the manufactor
ally use, but I cannot disclose those details here for IP reasons
5%, any 1% increase is really a monumental effort and takes real creative e ngineeringIt may be slightly larger than 7 USD, mechanics is hard to get in low volum e cheap from the get go
I am actually sort of working in that route. I do not have the funds yet to do a design like that, but I am working first on POL supplies. I have some thing in mind that I think would be sort of a gamechanger, but I do not wan t to reveal it here in a forum. Can I write you a private mail, for your op inion, since you seem to have used at least some number of different POLs o ver time?
Cheers
Klaus
I'll take some pics of the bigger unit, which has a fan and isn't potted.
Really, these MeanWells are good. I want to get reliable products done, emphasis on DONE, so we don't want to design and certify a power supply that we can buy, all boxed and tested, for $100 or so.
Smaller stuff, like dc/dc bricks, we usually buy for a few dollars. CUI, Recom, Murata all make good stuff, but I test a couple to be sure.
-- John Larkin Highland Technology, Inc lunatic fringe electronics
My Brit colleagues laughed at me when I thought CE was serious.
-- John Larkin Highland Technology, Inc lunatic fringe electronics
I design circuit boards, which usually have a single DC input and various switching and linear regulators here and there. I guess you can call that POL regulation. A small board might have 4 or 5 different rails, and a big one can have a dozen or more. My new alternator simulator uses a 48v 800w MeanWell as the prime mover, feeding 7 different boards. The big power supply costs 0.6% of the selling price... a different market from your high-volume stuff.
Sure, I'd like to take a look at your idea, maybe add suggestions. Confidentially, I promise.
-- John Larkin Highland Technology, Inc lunatic fringe electronics
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