86% Efficient AC-DC ATX supply - Page 3

rushnrockt · 11-24-2004, 01:06 AM

I am not going to be quoting anything this time. This has obviously gone far enough and you take yourself WAYYYYYY too seriously. My "minions" comment was a joke, nothing more, it was a joke. Has nothing to do with my mistrust of anything. Except may be armed people (another joke).

And no, you might not have been talking about cars, but I WAS, and standards apply not just to semiconductor industry, they apply to just about every industry. Just look at how many different branches of governments exist to implement them. So that was just an example for other readers that might not be quite as interested in our semiconductor analogies.

And as far as no assumption about pc components in a car... well, I made that assumption since I assumed that most people in this forum are interested in just that.

Now that I am not giving you so much stuff to quote, may be you can go ahead and read the other thread I started today, about building own power supply. I am sure you are going to be much more useful in there than discussing other producer's intentions and quality control. When I am done with my project, you will for sure know my intentsions and my specs and can discuss whether or not I achieved them. Thank you in advance for any constructive input.

ColdPhreze · 11-24-2004, 02:45 AM

MrPerfectionest, since you insist and persist, I will make clear the entirety of this, so that you can comprehend all of it, despite my better judgment.

Let's establish some rules for this post first, since you want to nitpick.
1) I tend to generalize so that it doesn't take so long to explain. I will attempt to avoid that here.
2) Whenever I say "max power output", or something similar, I mean the maximum CONTINUOUS power, not peak.

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…which clearly shows you have no clue what a specification is. Please get this concept iinto your head. A specification is the law when we are talking about things of this nature.

I was referring to two different things. One was the actual specifications. The other was how you use the PSU on a day to day basis. Opus doesn’t specify daily usage statistics, which is going to affect MTBF quite a bit due to heat, power on surges, etc. and their related effects.

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if they don't meet the ripple specification (wow there is that word again) set forth by the ATX standards committee then there is a good chance whatever is attached to the Opus simply won't run at the specs they say.

Correct (however, some pc configurations will still operate when exceeding the specs). But that isn’t my point. I never said they weren’t good PSUs, just that it is SAFER to keep to the 80-90% rule I outlined, and go into detail below.

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So you make the statement about only 120-135W as a general power consumption, but you confounded your own claim with the statement about stressing one rail. The second statement was correct and could have stood on its own.

My guess is you will attempt to claim (this is your change the argument/claim strategy) that by the 80-90% safety factor you will protect all rails from being overstressed. This too can readily be shown to not work in all situations.

WRONG WRONG WRONG. You must consider BOTH the rails separately and together as a whole. Why? There are 3 parts to this:
1) Each individual rails max power cannot be exceeded.
2) If you take each individual rail, determine its max power, and add them together, it may be higher than the whole PSU's max power.
3) This is similar to 2, but different. If you take each individual rail, determine it's max power, and add them together, it may add up to the claimed max power output of a PSU, which will likely be incorrect because there are other things to consider, such as temperature coefficients and rise, instability at high currents, and just the general parasitic effect of pushing large currents, which will make the max power of that PSU actually lower.

To be specific, the 80-90% safety factor should be determined by taking 80-90% of each rail individually and adding it up, and then taking 80-90% of the rated max power. Then, take the lower calculated power. This is still not entirely correct, because of above part # 3. If you can find any information on the PSU’s combined max power, then take 80-90% of that. Now, take the lower calculated power of all 3. The rebuttal of needing this safety margin is discussed below.

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Your experience is based on AC-DC power supplies which the Opus is not and exist in an application and market entirely different (which I explained a couple of times).

You just made an assumption that I have never worked with a DC-DC PSU. In fact, I have experience with a 150 watt Opus. I don’t use it and don’t even have it anymore. Yes, the retail markets are different; however, it does not mean they did not fib in some way. They could have just left something out, such as the temperature at which the MTBF was rated (which we don’t know) which will drastically affect it.

Their (meaning an Opus versus an inverter w/ AC PSU) method of generating power is somewhat different, but not wholly. If you consider the fact that an Opus can operate at voltages lower than 12v, then you must agree that it has some sort of voltage step up in it to generate the 12volts required by a PC. The ONLY way to do this is by converting to some sort of AC. It’s called buck or flyback converters, but it’s a form of AC. Granted, its high speed, etc. etc. but it is done. The high switching speed is one big reason for its efficiency. Thus, there is a DC-AC conversion in it. It is entirely internal to the PSU, but it exists, even if it is inside a chip in the PSU (which it is likely not entirely contained within one chip). The point of all of this is to show that experience with an inverter and 120VAC PSU setup is not completely different from a DC-DC PSU. Don’t forget, I do have experience with Opus… The real point you were trying to make is clear from your next statement, which I rebut below.

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While the spirit of this statement is ok (that more heat can cause more failures), it is based on other devices that may or may not be similar similar to the Opus in their built in robustness. Yes the curve gets exponential near the edge. But the only component you consider is the Opus itself and you go by a single 150W number as given by the manufacturer. What you don't understand is the technology that is actually in the Opus and your blanket statement about component failure can't be readily applied to the 'system' that is the Opus.

You hit the nail on the head: the spirit of the statement is ok. The rest is just nonsense, because there are lots and lots of recent posts where people have all kinds of power related problems with their Opus. By that alone, it cannot be as robust as you believe. Besides, how can YOU say anything about understanding the technology of the components inside an Opus? Do you work for them, or are u buddy-buddy with them, or have you reverse engineered it? If not, then you can’t really make any statements about the technology in an Opus.

The bit about me considering the Opus itself and only considering the 150w number was in an effort to conserve typing. It did not seem necessary to point out that each and every part creating heat in the Opus is subject to heat degradation, and since I had already mentioned the bit about checking the max total output and individual rails I did not see the need to go over it again. I also didn’t see the need to point out how that temperatures also increase more quickly at the upper ends and beyond the max power ratings of the rails and PSU as a whole. And again, the high temps accelerate the breakdown of electronics.

80-90% Margin rebuttal part 1 & continuation of previous paragraph:
I don’t care if you are within tolerance limits, electronic components, especially those of high power, slowly break down. When tolerances are approached, you approach and begin ascending the exponential portion of the breakdown curve referred to above. But when tolerances are exceeded, you are well into the exponential curve, and these parts will die quickly even if current overprotection exists. This is because current overprotection is not instantaneous and often allows the device to operate for some time after an over-current condition occurs. Many over-current protected semiconductor devices cannot even stand to correct a continuous over-current condition, and will fail when subjected to one.

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You don't have to consider total power if you consider the individual rails alone, this concept alone nullifies your original 80-90% claim (among other things).

I rebutted that above with the 3 part thing.

Continued to next post because of 10000 character limit...

ColdPhreze · 11-24-2004, 02:46 AM

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Its amazing how you know this information and can make this claim despite Opus saying the MTBF (thats 'mean time before failure' in case you didn't know) is 150,000hrs. Even if they fudge this number by a factor of 10 (pretty absurd don't you think?) the device can still be expected to live for almost 2 years at their ratings. On top of all this they give you a three year warranty.

I gave tons of other good reasoning supporting why I think your statements are completely and utterly baseless. In general your failure to respond is enough for me and hopefully others reading this post to realize you were wrong.

The point of all this that as long as a user of the 150W understand what his power draw is and stays just under the current specificationf or each rail (generally speaking it is probably even ok to go a little outside of it) they can expect their device to last quite a long time.

and

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If I worked for Opus I would be insulted by this comment. What gives you the basis to make this statement? People attaching multiple hard drives, lcd screens (these three alone probably enough to put us over the 5A rating on the 12V line) and other devices causing the Opus to break is certainly not a basis to make this claim. What answer do you have to the many multiples of people that have the Opus and are totally satisfied with them?

80-90% Margin rebuttal part 2:
First, there you go again saying it is prolly ok to go outside their rated specs a little. That is dangerous. No if and or but. It is dangerous if you expect the PSU to last. Specifications in electronics ARE NOT law, Especially in manufactured goods. Specs can be fudged in a number of ways, as I already stated. They may not have fully tested their PSU. The MTBF may be a guesstimate based from figures on the datasheets of parts they use, and they did not specify details used in calculating MBTF. I don’t think Opus PSUs are junk, just that they are not as rigorously tested as they lead you to believe, which means their MTBF is flawed or skewed. This may actually be the reason for the warranty being so long. They could be attempting to keep a good image while their data is bunk. I am NOT saying it is the case, I’m saying it Could be, I don’t know, neither do you. I base what I say upon reading other people’s posts that are having problems with the Opus, as well as my own experience with one. How long have you had yours, and how much current do you draw on each rail? I’m sure most of the happy users are either not overloading or not coming close to overloading it, OR they haven’t had it long and are overloading it or are close to overloading it. The rest we occasionally see in these forums.

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What is most funny is the fact that my name is spelled incorrectly on purpose, it is simply an ironic name. You missed that one too.

Figured you didn’t know how to spell it when you registered…. Just joking

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This can be easily seen in the peak ratings that Opus puts on each individual line. This is the guardband they are building into the product. They also limit the temperature range to 70C. Probably every component in the opus has a rating of at least 85c, some will have 100c and a few will even have a 125c rating. Since it is a switching supply it will be low in heat by nature. At 90% efficiency it is wasting 15W of heat at full power. At 70c (their max spec) 15W of heat distributed across multiple regulators isn't enough given proper heatsinking (which the Opus has) to raise the internal temps of any of the devices near high enough to become critical.

Have you check the specs of the parts in Opus? Do you know that they all are rated for at least 85c? I highly doubt the Opus is 90% efficient, but no one knows what it is. Anyway, using those figures you get 85c. That’s not too bad, but as parts get hotter, power dissipation increases, temps increase, and maximum safe current’s decrease, which suggests a loss of efficiency which causes more power dissipation and more temp increases. No one has bothered to test an Opus to see what its actual efficiencies are, so these numbers don’t count for much… We don’t know what temperatures or other specifics the MTBF was rated at either, so until we do, it’s useless, so stop trying to argue that an Opus will last and last at max power based upon the specifications alone.

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The hard drive won't pull more than it claims it will or will you assume that hard drive mfgs are lying about their specs also?

Apples and Oranges. No, I don’t think they fib about power consumption, they have very little to gain by lying about it. This is not the case with PSU manufacturers and power output. Now, if you wanted to make a similar statement about drive size, then yes, they do lie about the disk size. Once formatted, you have much less size than stated. Often, there is less disk size even when unformatted than what is stated.

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I fail to see how you can mistrue rebuttals to someone elses claims, backed by more experience, and more logical reasoning as an insult.

You simply comes across as insulting. It’s the way you go about attempting to make your points that leads everyone to see it as an insult. If that was not your intention, then I apologize for any & all insults I have made.

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For starters, we don't know how Opus did their MTBF. I would like to know where you got your 25C number from. There are a couple of different methodologies used to arrive at this number. I would hope that they would be calculating this value based on the typical target system which 25C certainly is not. If we assume that Opus isn't being fair then you have a case, but otherwise no.

We don’t even know IF Opus calculated the MTBF, or just made a guess. We hope they did real calculations, but that would be another assumption and too many have been made.

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You aren't understanding my argument. The market dynamics for AC-DC supplies (consumer desktops) by its very nature will contain the type of products that cause power supply skepticism. The Opus supply doesn't fall in this category and shouldn't incur the same level of cynicism.

That is your opinion, and I disagree. Any manufacturer should incur this level of cynicism when you start seeing people having problems as we have in these forums. Granted, many are pulling too much current, but others aren’t.

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If the supply is operated within the specification (what I have stated over and over and over again) set forth by Opus, then it will live and be happy about it. If you want to mix qualitative and quantitative metrics and theoretical assumptions about the operating environment, I can always argue that it is a very rare case that the opus is operated in a 70C environment AND I can also consider the peak rating Opus gives us (which is definitely higher than the 150W rating) which will null this 80-90% statement.

No, the peak argument does not nullify the 80-90% statement. Why? Because I am stating continuous power. What I have said: Your continuous power consumption should be 80-90% below the continuous power ratings for each rail and altogether.

Also, there is much information not divulged about the Opus ratings, so we cannot base everything on them, as you do.

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Hold on now. I have never made an assumption about pc components in a car. That is a whole different can of worms.

Many of these parts were not designed for the car. An exception is the Opus, but it has no long-term history here, so we still don’t know if it is up to par as far as physical mounting, ability to withstand constant vibrations, etc.

Now that I have covered everything I can think to right now, I have compiled quite a bit of data. So do you see why I generalized before? I am going to bed. I have wasted too much valuable time on this, which is why I did not want to post again just to continue an argument; it had nothing to do with you disproving any part of my argument.

ColdPhreze

fuctup · 11-24-2004, 04:27 AM

Quote: Originally Posted by mushin

OPUS! Opus solves EVERYTHING!
j/k

There's an interesting thread going on about skipping the DC-DC or DC-AC-DC altogether and using cheaply acquired deep cycle batteries instead. You'll still need to isolate your charging system, but it may be worth a look.

not to jack the thread but you got any more info on this? i got a nice optima yellow top sittin around..

rushnrockt · 11-24-2004, 06:16 AM

Could not resist to comment, the 25C number comes from being in between the accepted "room temperature" of 22C and kelvin "room temperature" of 300K or almost 27C. Most electronic devices (except military, god knows what they do) have their MTBF calculated at that temperature since if anything, that's the most likely temperature they are going to be at plus it is a hell of a lot easier to test at temperature you have present in just about any company's lab. From experience, fiddling with ovens seems to be one of the punishments for overachieving engineers

That was my other two cents... which puts me at what, two hundred bucks? =P

MrPerfectionest · 11-24-2004, 01:01 PM

Yup, this is definitely my last post on this matter because I won this argument long long ago. You both continue over and over and over again to cling to ideas, assumptions, and logic that has no real root in the fundamental understanding of what a dc-dc converter (the Opus specifically) can do, one worse than the other.

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This has obviously gone far enough and you take yourself WAYYYYYY too seriously

This accomplishes nothing.

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And as far as no assumption about pc components in a car... well, I made that assumption since I assumed that most people in this forum are interested in just that.

Has nothing to do with the discussion we were having about the Opus.

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I was referring to two different things. One was the actual specifications. The other was how you use the PSU on a day to day basis. Opus doesn’t specify daily usage statistics, which is going to affect MTBF quite a bit due to heat, power on surges, etc. and their related effects.

This again shows your preexisting ignorance and your continued refusal to understand what a specification means in the high tech industry. These "daily useage statistics" don't exist and don't need to exist. The specification is the only thing needed to govern how the product can be used and the expectations about its performance.

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WRONG WRONG WRONG. You must consider BOTH the rails separately and together as a whole. Why? There are 3 parts to this:
1) Each individual rails max power cannot be exceeded.
2) If you take each individual rail, determine its max power, and add them together, it may be higher than the whole PSU's max power.
3) This is similar to 2, ... which will make the max power of that PSU actually lower.

Your own point #2 tears down any kinda of argument you could attempt to make. I should hope that you can do the simple calculation of voltage*current for each rail and see how Opus arrives at their 150W number. At this point I really shouldn't even bother to continue this discussion.

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If you take each individual rail, determine it's max power, and add them together, it may add up to the claimed max power output of a PSU, which will likely be incorrect because there are other things to consider, such as temperature coefficients and rise, instability at high currents, and just the general parasitic effect of pushing large currents, which will make the max power of that PSU actually lower.

No taken infinite times and No again for good measure. Their specification takes care of all these theoretical assumptions. There is no instability at a current they specify and they say it will do 150W up to 70C with input voltages as low as 7V. Again, I have plenty of knowledge of dc-dc converters and I understand that these claims aren't unreasonable.

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You just made an assumption that I have never worked with a DC-DC PSU. In fact, I have experience with a 150 watt Opus. I don’t use it and don’t even have it anymore. Yes, the retail markets are different; however, it does not mean they did not fib in some way. They could have just left something out, such as the temperature at which the MTBF was rated (which we don’t know) which will drastically affect it.

You had one and realized it couldn't do more than 150W safely. Again, your suspicion about Opus claims and specifications would bother me if I worked there.

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Their (meaning an Opus versus an inverter w/ AC PSU) method of generating power is somewhat different, but not wholly. If you consider the fact that an Opus can operate at voltages lower than 12v, then you must agree that it has some sort of voltage step up in it to generate the 12volts required by a PC. The ONLY way to do this is by converting to some sort of AC. It’s called buck or flyback converters, but it’s a form of AC. Granted, its high speed, etc. etc. but it is done. The high switching speed is one big reason for its efficiency. Thus, there is a DC-AC conversion in it. It is entirely internal to the PSU, but it exists, even if it is inside a chip in the PSU (which it is likely not entirely contained within one chip). The point of all of this is to show that experience with an inverter and 120VAC PSU setup is not completely different from a DC-DC PSU. Don’t forget, I do have experience with Opus… The real point you were trying to make is clear from your next statement, which I rebut below.

So the fact alone that there is some sort of DC-AC conversion is enough to say that the Opus design is similar to an inverter and an AC supply? Are you serious? I guess I should have similar expectations about my car stereo amplifier since it has a forward converter in it. Until you know how the conversion actually works (it isn't enough to know that it is buck or flyback) and what components are stressed please stop trying to make claims of this nature.

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because there are lots and lots of recent posts where people have all kinds of power related problems with their Opus. By that alone, it cannot be as robust as you believe. Besides, how can YOU say anything about understanding the technology of the components inside an Opus? Do you work for them, or are u buddy-buddy with them, or have you reverse engineered it? If not, then you can’t really make any statements about the technology in an Opus

Can you quantify these problems? From what I have seen it is from people hooking P4s and XPs and multiple hard drives and LCDs and power hungry video cards to their supplies which is killing them. Again, where is the basis for saying the Opus can't do 150W when people that are killing them are probably stressing out the 12V line (2 hard drives alone will eat 4A of the 5A rating during random operations)
No I am not buddy buddy with them but I have looked at the board and can readily identify all teh subcircuits and tell you want the components are doing. Yet again I will state about the plenty of knowledge I have about the converter, something you can't even begin to comprehend. This should be a foundation before you can begin discussion about this device, not your knowledege about AC-DC supplies and any assumptions or conclusions you attempt to draw from that.

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Have you check the specs of the parts in Opus? Do you know that they all are rated for at least 85c? I highly doubt the Opus is 90% efficient, but no one knows what it is. ... it’s useless, so stop trying to argue that an Opus will last and last at max power based upon the specifications alone.

I don't have to check inside the Opus. Had you any real knowledge you would know this. I invite you to have a look at any data sheet for capacitors, inductors, resistors, as well as the regulators used by the Opus to find this information. If you knew dc-dc converters you would also know 90% efficiency is readily attainable. This number would fall a little under light loads and a little under full load but nothing to be alarmed about and not enough for you to make a case.
You yet again challenging the Opus specification shows a certain distrust. If it bothers you that much then why don't you contact them for an explanation. Post it here.

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Apples and Oranges. No, I don’t think they fib about power consumption, they have very little to gain by lying about it. ... they do lie about the disk size. Once formatted, you have much less size than stated. Often, there is less disk size even when unformatted than what is stated.

So if Dell came to me as a hard drive manufacturer and they wanted hard drives for their laptops that wouldn't exceed 5W and I lied to them about my spec I wouldn't have anything to gain? And mfg. lying about drive size????? What? This can be readily proven. Wow. I bet you are a conspiracy theorist in your free time.

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We don’t even know IF Opus calculated the MTBF, or just made a guess. We hope they did real calculations, but that would be another assumption and too many have been made.

Amazing yet again. So they magically pulled some random number out of the air?

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That is your opinion, and I disagree. Any manufacturer should incur this level of cynicism when you start seeing people having problems as we have in these forums. Granted, many are pulling too much current, but others aren’t.

Show me a statistically significant number of cases where the Opus has failed under good (meaning within spec) operating conditions.

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No, the peak argument does not nullify the 80-90% statement

You didn't read the statement correctly. The peak alone certainly DOES nullify your 80-90 statement AND we can add on the fact that it won't ever operate in a 70C environment. You do understand how I am using this peak number aren't you? This is nothing like the peak rating applied to car stereo amplifiers if that is what you are getting at. The max continuous rating is what Opus says is ok and this extra peak they tack on there is guard band. They aren't going to specify the max continuous output to be right on the ragged edge of safety.

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Also, there is much information not divulged about the Opus ratings, so we cannot base everything on them, as you do.

It is all divulged right there in the spec. If you don't take anything from what I have said, understand that specifications exist for a reason. They aren't willy nilly contrived on the back of a napkin. They are debated, massaged, and then hammered out and used as the basis for product developement. At the end of the design phase the result is compared to the spec to see if it meets spec.

I think the most pertinent thing would to be to contact Opus yourself, feel free to attach a link to this thread. I would be interested to hear what they have to say.

hd54321 · 11-24-2004, 01:15 PM

All of you are taking this too seriously - just relax - let's not get all geeky on one another.

The Grinch · 11-24-2004, 01:15 PM

Er, guys. I don't know if you realize this, but in the world of power supplies EFFICIENCY ratings are a measure between input vs output power. So if your power supply is capable of producing 150watts of output, and it's rated efficiency is 90%, that means that you will draw around 165watts from your source.

This blurb From OPUS's website seems to validate my point:

· Why is a Opus Solutions, Inc. DC-DC supply better than an inverter and AC-DC power supply?
Opus Solutions, Inc. DC-DC supplies are over 90% efficient. Using an AC inverter paired with a regular PSU to power your vehicle based computer system can be as low as 50% efficient - placing extra load on your car's electrical system. Inverters can also create a lot of electrical 'noise' which can seriously effect the performance of your equipment.

rushnrockt · 11-24-2004, 04:08 PM

Too late, someone wanted to win an argument too badly, and since he is very much in love with himself, he decided that he won.... So I hope it is done with. Too bad that all his so called "expertise" was of no help in my post about making own power supply. So if anyone else out there has some ideas, check that thread out and please do make some real suggestions. Thanks.

ColdPhreze · 11-24-2004, 06:38 PM

Like I said before, it's a waste of my time pursuing this. MrPerfectionest doesn't fully understand what I am saying, when I am talking about PSUs in general vs. an Opus, or how smaller companies operate. (He has corporatitus - a condition of conformity and the inability to accept new ideas which exists when working for large companies for long amount of time - This is a joke!)

From now on, it is my policy to utterly ignore anything he says in any of my posts, comments, etc. He may have years of experience in a large company environment, but that doesn't mean smaller companies are anything like the one he works for. We don't know the size of Opus or anything about them, except the few PSUs we see. I agree that if Opus was the size of IBM or dell, specifications should damn well be iron clad. But we don't know if they pulled the numbers out of the air or calculated them, or are based upon real life scenarios. Maybe they did, maybe they didn't. Time will tell. Until then, please err with the idea to be conservative. It might just save you a few hundred bucks.

That was the real point of my original post. Err on reason. Ignore those who post that their Opus or any PSU will do more than rated, err with conservation and make damn sure the PSU will last. It's good advice when you are droping 2 bills just for a PSU.

ColdPhreze

KyferEz · 11-24-2004, 07:19 PM

I have to make a comment at this point. I am also an electronics engineer with many many years of experience.

All 3 of you have made very good points. Anyone reading this is well advised to read it in entirity before making any decisions.

MrPerfectionest is correct specifications should always be gospel, however, ColdPhreze is also correct about many companies fudging them. Does Opus? That is not something we can answer at this point.

rushnrockt is correct that it does appear that MrPerfectionest seems to be belittling when making posts, however, ColdPhreze did do some name calling and then apologized for it.

ColdPhreze is correct that any consumer should not try to push the specs of any product produced for consumption by the public. MrPerfectionest is correct that we shouldn't have to, however, I inject we so often do that it in ingrained into us by now.

hd54321 is right, don't make such a big deal of all this. MrPerfectionest, ColdPhreze, neither one of you won any argument, you both just made asses of yourselves.

KyferEz

eCar™ · 11-24-2004, 08:19 PM

I think everyone that posted anything in this thread is completely wrong on all accounts. Especially me.

;-P

nickmig · 11-25-2004, 03:16 AM

my power supply is 91.4% efficient

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