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    #41
    Re: Suggestions for PSU improvements

    On the EMI filter yeah probably all of the above listed.

    Mostly now on the PCB but older (lower power) supplies did tend to have them.

    What you find with the cheapie PSU's the positions might be on the pcb but not the components
    (any supply like that the best place for it is the bin)
    You may find this area skimped on component quality wise too.

    heres an example of a cheapie "lets throw away the EMI filter" well half of it and use possiblely (more likely are) sub standard caps
    (lowewr left hand corner, were the red white coil is)

    just as a side point
    this one was missing 2 resistors that would have forced equal voltage across each of the mains I/P caps, which probably explains the stuffed vented cap at the top
    (No Mov's either)....
    In short junk not worth fixing and there's a lot of it out there.



    Active PFC (power factor correction)

    Well found this link and it has a bit of a tutorial on it...the really good part is it has lots of chips listed and links to PDF's humm

    Power Factor Correction IC's

    Just click on the link at the top "View All Products In This Category" if you want to see the whole host of chips about 3 pages I think

    This site looks like a handy one...why haven't I found it before LOL

    just on your question of adding PFC, you might get away with Passive PFC
    but Active is a whole different ball game from what I gather.
    Its intended purpose really is to keep power companies happy not consumers from what I understand.
    I think generally speaking there is really little benefit to the consumer and it more the fact laws have been pasted so PSU manufacture have no choice but to comply if they want to sell their psu's in certain countries.

    Anyway thats the story as I understand it but not the guru on PFC either.

    HTH Cheers
    Last edited by starfury1; 10-23-2007, 04:19 AM.
    You step into the Road, and if you don't keep your feet, there is no knowing where you may be swept off to." Bilbo Baggins ...

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      #42
      Re: Suggestions for PSU improvements

      As long as the switch is no concerted action with subsidy payments, it's luxury and not necessarily economically feasible for the average guy.
      You can't deny, however, that (like everywhere else) it all adds up, and although the gain may be insignificant to the individual consumer, the relief on the grid may well make a difference (and you can't deny that 'the grid' in the US is having its problems, either).
      Question as always: Who pays for it?
      "Every normal man must be tempted at times to spit on his hands, hoist the black flag, and begin slitting throats." - H.L. Mencken

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        #43
        Re: Suggestions for PSU improvements

        (I seem to be too stupid to edit my previous post)

        I must admit that I don't have any numbers here to back up my statements, but I also understand that one of the major problems in the US is reactive power, partly due to heavy use of air conditioning in private households.
        That's a big difference between Europe and the US. When a grid is already running at its limits, this can easily bring it down to its knees on a hot day.

        Thus, the recent regulations on PFC in consumer electronics are a good start, that's for sure.

        Sorry... back to the original topic. Maybe we should start an extra thread.
        "Every normal man must be tempted at times to spit on his hands, hoist the black flag, and begin slitting throats." - H.L. Mencken

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          #44
          Re: Suggestions for PSU improvements

          PFC
          Thats the point, its Real benefit is to the grid on the whole
          not the consumer.
          (well in a round about way I suppose it might be to the consumer)
          But since manufacturers are now being forced to clean up there act in this regard
          I guess they are using a bit of slight of hand to sell something now thats costing them a bit extra, so they are playing up the advantages.

          I suppose I should have made it a bit clearer

          Retro fitting PFC to a supply that doesn't have it would be of little advantage really to you I think.
          So if it isn't there its not worth worrying about

          Active PFC in a new design PSU may have a bit more pluses for the consumer but I still think its small advantage really.
          others would have more informative input on it in this regard
          As an environmental move probably a good one thought.

          On the mains thing happing in this Thread I am a bit all "mains-ed" out after another thread to do with mains systems and the world so got no real comment on it.

          Cheers

          Oh you only get 10 min to edit your post after you post it....its set in stone then and you cannot edit it (so used the preview before posting it)
          Last edited by starfury1; 10-23-2007, 05:56 AM.
          You step into the Road, and if you don't keep your feet, there is no knowing where you may be swept off to." Bilbo Baggins ...

          Comment


            #45
            Re: Suggestions for PSU improvements

            Adding PFC requires having a good look at the EMI filter, too (besides many other tweaks), as the PFC puts out substantial noise.
            Those points are usually covered in a decent PSU. Active PFC may cost a few % of overall efficiency, but nevertheless there are many good units that are within the 80+ specs.

            All I'd recommend is to buy a half-decent unit, screw the warranty and do a recap right away. Oh, and that dreadful fan thing.
            "Every normal man must be tempted at times to spit on his hands, hoist the black flag, and begin slitting throats." - H.L. Mencken

            Comment


              #46
              Re: Suggestions for PSU improvements

              What is a reasonable value for the EMI filter if I were to install one in the PSU? 6A 8A 10A on the 250V? There are fused ones as well.

              And what is the consequences if the PCB has an existing EMI filter? Will it affects the operation by any means?

              Secondly, I was hoping of adding one to my speakers-bassbox. Everytime, I switched my PC on, there will be this big 'boom' from the speaker unit on the same power bar. Will this help or an EMI filter on the analog-input-signal instead? Thinking of a solution to clean up the signal and interference

              APFC seems the way to go as most of the 80-plus PSU are spotting active PFC. Is there any PSU with passive PFC but still on the 80-plus list?

              I know the myth/fact that the PFC is not helping the consumer, but the more recent PSUs use this technology to pull themselves above the 80% efficiency mark.

              I did read some articles on Tomshardware whereby some PSU are more tolerent to overloading. They are rated at 300W but possible to power up to 350W, that's quite an improvement I must say. Is there some chokes or caps or resistors whereby we can tune up the power output?

              Got the link off www.smps.us. Article is 2002 but it is worth a read : http://www.tomshardware.com/2002/10/..._verax_and_tsp

              <- Sir Ask-A-Lot enjoys your brainstorming
              Last edited by ChaoZ; 10-23-2007, 10:32 AM.

              Comment


                #47
                Re: Suggestions for PSU improvements

                Originally posted by ChaoZ
                What is a reasonable value for the EMI filter if I were to install one in the PSU? 6A 8A 10A on the 250V? There are fused ones as well.
                Depends on how much margin you want? You should have about 1A per 100W output. I'm too lazy to do all the math but it's basically [output power/efficiency] / [power factor * AC->DC voltage]

                And what is the consequences if the PCB has an existing EMI filter? Will it affects the operation by any means?
                It will be redundant, achieving a little more filtration and a little less efficiency but really the point is what the goal is, why you'd add it. These filters are meant to isolate PSU from line and line from PSU, they can't get rid of all line noise, nor do they really need to as a switching psu has a noisey output inherant in that it's a switching PSU, really sensitive circuits can't use switching PSU or moderate circuits would have addt'l filtration betweeen the psu and the circuit isntead of filtering higher current for things that don't need power so clean. For example the audio subcircuit on a motherboard.

                Secondly, I was hoping of adding one to my speakers-bassbox. Everytime, I switched my PC on, there will be this big 'boom' from the speaker unit on the same power bar. Will this help or an EMI filter on the analog-input-signal instead? Thinking of a solution to clean up the signal and interference
                It might help some but probably not a lot. You didn't describe this "speaker unit" but it's most likely it has a rather poor unregulated PSU and that should be upgraded first, OR the input to it has noise when the PC is turned on. You might try using something else as an input (not leaving the amp/speakers floating/disconnected) to see if the noise persists when the PC is turned on. Ideally, use something line-isolated like a battery powered MP3 player so only the Ac power noise is a factor.
                Last edited by 999999999; 10-23-2007, 11:16 AM.

                Comment


                  #48
                  Re: Suggestions for PSU improvements

                  PFC is for a private customer not of any benefit to him (but to his power company)

                  Most large companies have to pay for reactive power however, so for them having a good PFC is very very important

                  My dad told my about a story; local sawmill, they have a custom PFC setup, basically a room full of really large capacitors. They help bring up the PF value close to 1.0

                  These caps failed withut the company noticing; untill next month when they got their power bill; as their PF had become lower than a specific threshold not only did they have to pay for the extra power they had drawn.
                  But also a fine for drawing more current than they where allowed. The sum of that was in the region of $20000 total... (excluding normal power draw cost)
                  "The one who says it cannot be done should never interrupt the one who is doing it."

                  Comment


                    #49
                    Re: Suggestions for PSU improvements

                    From a theoretical point of view the private owner has no benefit from A-PFC.
                    But in real world i do not know any 80+ PSu which does not have an A-PFC circuit.
                    Even the LC-Power Green Edition does not com close to this value, as only P-PFC PSu i know marketing the efficiency or better said the "green" vocabulary.

                    Furthermore i think, that a bad PFC really does increase the producing (more mechanical power) and distribution cost, and i think it is somehow foolish to think that now one would pay for this.
                    Sure those kind of costs are not direct cost subjected to your bill, but never the less you pay it.
                    If you using a air condition, you even pay twice for a energy wasting PSU, this time directly at your own bill.
                    Last edited by gonzo0815; 10-24-2007, 11:06 AM.

                    Comment


                      #50
                      Re: Suggestions for PSU improvements

                      Originally posted by Elitist
                      So my time in the US wasn't wasted and my advice was correct. Read what I said - not what you would like me to have said so you can make a lame attempt to put down a foreigner. Your arrogance is what makes your country the least popular. Neither your country nor mine has a monopoly on perfection in design and application. Most of our stuff is aged and decaying because we were 'first'. However, after WWII, we were forced to changed our electrical installations, which makes our present designs newest and safest, bar none.
                      Notwithstanding, you will find that your a/c and fridge, cooker if it's electric, all run off the 220 line. Nobody is asking you to rewire houses, change your plugs, etc., but if you did adopt the British wall plug, which is the only one with a safety shutter activated by insertion of the earth pin, you could rid yourselves of those dangerous two-pin monstrosities. Cheaper-by-the-dozen, I'll gift you a box - they're only a few quid. You supply the wall receptacles.


                      Elitist

                      My a/c and fridge are in fact 115v just as I said.

                      Window AC units under ~15,000 BTU and ALL household fridges in the US are 115v.

                      I didn't put you down for where you are from.
                      (I in fact never looked because I don't care.)

                      I didn't put you down either. (Yet)
                      I put your IDEA down because it was impractical and stupid.
                      You clearly have NO CLUE about how houses are wired here.

                      YOU were asking us to rewire our houses because... you clearly have NO CLUE about how houses are wired here.

                      The 220 to 115 change occurs ~IN~ the main power box by splitting the 220 phases with a ground phase -> ~IN~ the main power box.

                      The only 220 lines in a home here go to the cloths drier, Central AC/Heating (which many house don't have), and the oven/stove.
                      (Unless they are natural gas which mine happen to be.)

                      Beyond those, there are ZERO 220 lines running through a home here.
                      - The 220 stops at the power box.
                      - There is no 220 in the walls. NONE. ZERO. ZIP.


                      How do I know this?
                      -
                      I have completely rewired 1 house myself (100% replacement).
                      In 3 house I replaced the main power box. (Myself - don't tell the power company!). Old houses here usually only have 100 amp main boxes which is not adequate for some of my past hobbies.
                      -
                      I was at one time qualified as an electric plant operator in a 1.1 Giga-watt (special purpose) power plant. The distribution there was 4160v AC. (I don't mean just the output of the generator. The entire distribution was 4160v. If something required less voltage there was a 4160 to ____ step-down xfmr at the piece of gear. It's breaker on the load center was 4160.)
                      -
                      The control systems I worked with equivalent to a computer's PSU had to be tuned to +/- .0005v DC simultaneously on multiple rails. (Adjusting any rail affected all the others.)
                      -
                      I've worked component level on micro-electronics circuits the size of the PCB on a laptop hard drive that cost $30,000 US. (In 1990's dollars.)
                      -
                      For a time after I 'retired' I took a job as the shift supervisor for the maintence department of a factory. My load centers and equipment were a mix of 440/460, 220/230, 115 in both single and 3 phase.



                      I have quite the range of electrical and electronics experience in the US. (In addition to having worked for short periods in something like 20 other countries.) So don't you try to tell ME how the power distribution works here at home.



                      ~~

                      The US least popular?
                      Is that why all these people keep immigrating here?

                      Still pissed about WW2? --- I wasn't even born yet.

                      ~~~~


                      To the rest of you,,, Sorry for the rant....

                      I guess by know everyone knows I'm an old grump.
                      Maybe I should change my handle to Grumpy?
                      ???

                      .
                      Mann-Made Global Warming.
                      - We should be more concerned about the Intellectual Climate.

                      -
                      Be who you are and say what you feel, because those who mind don't matter and those who matter don't mind.

                      - Dr Seuss
                      -
                      You can teach a man to fish and feed him for life, but if he can't handle sushi you must also teach him to cook.
                      -

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