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  #31  
Old 03-06-2007
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Quote:
Originally Posted by Lenny_Nero View Post
Did anything come of the re-capping/ ripple testing ?
http://www.jonnyguru.com/forums/showthread.php?t=1450
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  #32  
Old 03-06-2007
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When you MUST balance and can not remove metal, Mallory metal is added to achive balance. It is about as heavy as tungsten.

The recapping/ripple article is on our front page.
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  #33  
Old 03-07-2007
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In the audio world, and on simple power supplies, ie transformer, rectifier, series choke perhaps, and shunt ( to ground) capacitor, ripple is reduced by larger value capacitors, and bigger chokes. Trouble is, too large, and you can stress the parts preceeding them, as the bigger the cap, the more the peak charging current drawn, which can be very high indeed.

Also, voltage regulators( which make the voltage regular, as a matter of fact, ie unchanging), which aren't present per se. on a smps (done mostly by the pwm, which I don't understand the workings of yet) ...I did 2 yrs of a degree in electronics over 10 yrs ago, and didn't know what I was really doing, I am only now more understanding, but have a long way to go still.

I havne't done too much reading lately, a lot of my knowledge is over a year old, so I am very rusty, but I think I am correct in saying that under harsh conditions, ie high current draw..ie your computer parts being stressed, the regulation and ripple will be worst, obviously, as the capacitors are discharging their energy store more, so the droop/sag will be more pronounced.

So bear in mind that its largely under extreme conditions that the differences in psu's become pronounced, and yes electronic design has a huge bearing, so does components. So in the rare instances that you are demanding say 850 watts, it may be the case that such conditions make it irrelevant for most people, then again, it may be common in your rig due to useage and component parts, ie demanding chips in the cpu, and graphics, etc., that such powers are drawn, so you have to have the best possible, which makes sense, ie you can never have enough.

There is little you can do about design, the people who do that are very clever, and can do it in their sleep, and amateurs such as us MOSTLY can't do better, but yes, we can improve components based upon cost decisions. Bear in mind tho', that also time is money, and it takes more time to engineer something to a high standard, so the design may be the primary factor here, ie. its just not worth trying to make a silk purse out of a sows ear.

Another caveat is, it may be more worthwhile due to time and hassle, simply to buy an overkill psu, than get a cheap one and improve it, thinking it can be done on the cheap, remember its time and hassle, which factored in, may not make it worthwhile, still its good to play and learn.

I think with electrolytic caps by and large, that you get what you pay for. I never got into finding out too much about low esr, lowest is best of course, and its at the edge of my knowledge on ripple ratings, so it may be a smaller cap with better ripple may be better than a sledgehammer big one, but my instincts would say go with the bigger value secondary caps, and possibly primary, which probably is of significant importance, as it sets the tone for what follows.

Voltage wise, of course, is vital, it may be possible to reduce voltage ratings if they are way overdone, say 50volts cap on a 3 volt rail, but even so, better safe than sorry.

If there is a guinea pig of a power supply that is expendable, it may be worth doubling the value of capacitance, but controlled, ie on the say primary first, or one of the rails, and seeing if that is fruitful.
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  #34  
Old 03-07-2007
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The rule of thumb over at Badcaps (site is down for work ATM) goes like this.
Capacitance can be increased one value up.
Voltage can be reduced but must stay above the working voltage.
ESR can always be reduced if possible.

willawake is a very helpful tech at Badcaps. He put this site together.
http://www.capacitorlab.com/index.htm


I am far from expert on any of this.
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  #35  
Old 03-07-2007
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Quote:
Originally Posted by GalvanizedYankee View Post
When you MUST balance and can not remove metal, Mallory metal is added to achive balance. It is about as heavy as tungsten.

The recapping/ripple article is on our front page.
Ok, I understand, we just always have a load of excess to remove anyway. I was only trying to explain to a customer the other day that it would not be best for him to have the lightest flywheel we could do, because he wanted to drive it on the road everyday and that there is a reason for the weight.

I did have a search around after I made the post, should have done that first. As for changing caps I have only gone after caps for their sound quality in stuff I have changed them. This is an interesting area.
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