voltage difference limit?

[chipper]

Re: voltage difference limit?

Chipper, you are a moron.

Going with you failed attempt at an analogy: Using a cap on a voltage UNDER it's LIMIT would correlate to using a fuse on a circuit that pulls LESS amps than the fuses' rated LIMIT. - With your numbers - 15 amps through a 30 amp fuse will not blow the fuse.

What I've told you is correct and very VERY VERY basic electrical knowledge.

.

Check your moronic status : I said that if you installed a 15amp fuse in place where 30amps is required it will blow.

[chipper]

Re: voltage difference limit?

The voltage stated in a capacitors ratings is a LIMIT not a goal.

What you say is idiotic.
- Examples right in your face:

16v caps on a motherboard are on 12v power. - NOT 16v power.

Both 10v and 6.3v caps on motherboards are used on BOTH 3.3v and 5v power.
- NOT 10v and 6.3v power.

10v is OFTEN used in place of 6.3v on BOTH 3.3v and 5v power because they are larger physically and tend to have lower ESR and higher ripple.
- 10v cap on 3.3v power is normal from the factory on some boards and in MOST PSU's.

Go find a 2200uF 50v cap and tell me how big it is.
- And how much it costs.
- Tell me how you are gonna stuff 10 of those in next to your heatsink on you mobo.

.

I am not questioning what voltage is installed on what power supply or circuit , I am saying that in an integrated circuit there are other parts that rely upon what voltages have been installed , exceeding any of them may cause a failure. There are many threads and many PDF documents about IC's and all sorts of regulators etc. (including controller chips) , that demand that the "voltage" not be exceeded or changed in any way.

Obviously if you "decrease" the voltage application of a capacitor it will have an adverse effect on the integrated circuit in different places. But , the point is that the voltages of installed capacitors should not allow any overcurrent or storage when attached to the integrated circuit design characteristics.

Check out the wikipedia on "rectifiers" , and what it says about how they need to be installed and what will happen if the voltages are increased .

[chipper]

Re: voltage difference limit?

The voltage stated in a capacitors ratings is a LIMIT not a goal.

What you say is idiotic.
- Examples right in your face:

16v caps on a motherboard are on 12v power. - NOT 16v power.

Both 10v and 6.3v caps on motherboards are used on BOTH 3.3v and 5v power.
- NOT 10v and 6.3v power.

10v is OFTEN used in place of 6.3v on BOTH 3.3v and 5v power because they are larger physically and tend to have lower ESR and higher ripple.
- 10v cap on 3.3v power is normal from the factory on some boards and in MOST PSU's.

Go find a 2200uF 50v cap and tell me how big it is.
- And how much it costs.
- Tell me how you are gonna stuff 10 of those in next to your heatsink on you mobo.

.

A good example can be found of "overvoltage" can be found by typing in your search engine ( TB1328FG ) , it's 47 pages long but it shows just 1 of the many onboard chips present on new televisions. Pay close attention to what it says about ever receiving (or even potentially receiving ) too much voltage.

[arneson]

Re: voltage difference limit?

I'm getting it now.
So Horton put a bigger battery in his hearing aid and was able to hear a Who.
Finally the thread is making some sense.

[chipper]

Re: voltage difference limit?

A good example can be found of "overvoltage" can be found by typing in your search engine ( TB1328FG ) , it's 47 pages long but it shows just 1 of the many onboard chips present on new televisions. Pay close attention to what it says about ever receiving (or even potentially receiving ) too much voltage.

PAGE 32 :

Note 5: Pins of this product are sensitive to electrostatic discharge. When handling this product, protect the
environment to avoid electrostatic discharge.
Note 6: Install the product correctly. Otherwise, it may result in break down, damage and/or degration to the product
or equipment.
The absolute maximum ratings of a semiconductor device are a set of specified parameter values, which must not
be exceeded during operation, even for an instant.
If any of these ratings are exceeded during operation, the electrical characteristics of the device may be
irreparably altered and the reliability and lifetime of the device can no longer be guaranteed.
Moreover, operation when these ratings are exceeded may cause break down, damage and/or degradation to any
other equipment. Applications using the device should be designed such that each maximum rating will never be
exceeded under any operating conditions.
Before using, creating and/or producing designs, refer to and comply with the precautions and conditions set
forth in this document.

[chipper]

Re: voltage difference limit?

A good example can be found of "overvoltage" can be found by typing in your search engine ( TB1328FG ) , it's 47 pages long but it shows just 1 of the many onboard chips present on new televisions. Pay close attention to what it says about ever receiving (or even potentially receiving ) too much voltage.

What kind of contradiction is : taking a 2200uF x 50v capacitor and trying to put them onto your motherboard , when you are stating that that very thing is OK , since any capacitor can handle whatever it receives as long as it is not "under" the capacitor rating having been replaced?

I wouldn't hesitate to install any capacitor onto any of my motherboards as long as the specs were the same or the voltage was equal (not more or less). The fit is an obvious requirement. So , if you had a small 10v capacitor in your motherboard , why put in a 25v capacitor , when it will be bigger and potentially create an "overload" hazard?

[PCBONEZ]

Re: voltage difference limit?

ESD on caps!!!!!!!!!!!!


Caps are ~DESIGNED~ to charge and discharge!


You need to stop playing in forums and GO STUDY SOMETHING.

.

[PCBONEZ]

Re: voltage difference limit?

A 2200uF x 50v cap is HUGE - DUH!

You again show a complete lack of practical experience.
Are you out of high school yet?
Made it TO high school yet?

.

[chipper]

Re: voltage difference limit?

ESD on caps!!!!!!!!!!!!


Caps are ~DESIGNED~ to charge and discharge!


You need to stop playing in forums and GO STUDY SOMETHING.

.

Whatever you say : just keep bumping up the voltage on your cap replacements and the next time lightning strikes your system , your caps will all allow the voltage to be double of what the circuit is designed to operate with. Caps store voltage , and if you were to tell a company you replaced the caps with higher voltage caps , they could laugh you right out of any warranty you had with their "disclaimer" portions.

I don't think I would want to see what would happen to a very large cap that was trusted to "discharge" on it's own without any place for the power to go safely on any system with microprocessors or semiconductors attached anywhere. It could mean you might have to download some foreign languages or encryptions to see anything afterwards.

As far as high school goes - that was 20yrs. ago. But your estimate "could" be considered.

[gdement]

Re: voltage difference limit?

You seem to be thinking that a 100V capacitor will somehow drive the circuit to 100V. There's no way for it to do such a thing. The capacitor does act as a damper, resisting momentary changes in the voltage, but it has no ability to drive the nominal voltage higher (or lower) than it is.
The voltage rating written on the cap is just a max rating.
For another auto analogy - new shock absorbers don't make your car heavier.

[chipper]

Re: voltage difference limit?

I'm getting it now.
So Horton put a bigger battery in his hearing aid and was able to hear a Who.
Finally the thread is making some sense.

I don't need a hearing aid , just a 10,000 volt tester :

Personally , I am going to take some of the "good" advice being given to my uneducated "Redneck" ass , and intentionally install as many higher voltage caps as I can on my mobo , near the processor , where I can realize a temperature of 100 C. , (Blizzard Heat OC 2008) roof ice melting system - thereby making my 266mhz into a 3266mhz with DDR4 Memory specs. (no memory boards required) - voltage jumps across the DIMMS.

Then I'll hook up a bigass 2000mhz video card to some more linked overvoltage caps (say 10000uF x 50v or so X 10 - STK10's) to reach the 1000 volt range on my mobo secondaries platform , (what a buzz) designed just for making sure I have enough power to enable it all. If and when they discharge enough on their own , the ground wire will take any inherent voltages and pass them to my case grounding system , (barbwire) which will be attached to my TV cable , (& phone line), shooting it miles away from me out of danger into the ground somewhere. The neighbours won't mind the red glowing cable wires , cuzz I'll do it when they are asleep. (I have no idea where the fire started - looks like the cable cooked the carpet) Their fault.

***
Damn , some people don't understand instructions that tell them to manually discharge any capacitor before measuring it . They firmly believe that there is no power in these things when the circuit is off. Where do the sparks come from? [NEIGHBOUR'S COMPUTERS] Brick Walls ! Call an ambulance while he is still twitching. There's lots of blown meters around because of that misconception.

[chipper]

Re: voltage difference limit?

You seem to be thinking that a 100V capacitor will somehow drive the circuit to 100V. There's no way for it to do such a thing. The capacitor does act as a damper, resisting momentary changes in the voltage, but it has no ability to drive the nominal voltage higher (or lower) than it is.
The voltage rating written on the cap is just a max rating.
For another auto analogy - new shock absorbers don't make your car heavier.

If you check around you'll find all kinds of information that says different. Without going into detail , there are informations about capacitors not discharging as a result of being loaded all the time. And if they don't completely discharge , then they are always charged somewhat. The more I look the more it is confirmed , that adding voltages that do not belong in a circuit will destroy components and circuits. Specifically , there are informations that speak of full time loading of a capacitor , where it can build up and blow through the bottom or the top , and that is the norm. The vent on the bottom of caps is for any overheating while the top is for overvoltage escapement. Not over resistance of any kind.

[Gianni]

Re: voltage difference limit?

@ chipper: read here please.

Caps store voltage

From the formula here attached you can see that caps store energy not voltage.

From the formula you should clearly understand the the energy stored depends on applied voltage and capacitors value.
In motherboards, if you replace a cap that is 10V instead of 6.3V, you are not going to bring the voltage in the circuit at 10V.
If you use a bigger cap, which is very bigger compared to the original one, you can store more energy so it will take more time to charge and discharge it.
As SMPS, buck converter, flyback, boost converter... are design to work with some margin, changing the caps with same value ( uF ) and ESR it is the better choice, increasing or decreasing the value could be unsafe because you change some parameters in the circuit. Usually the feedback loop is designed to keep the voltage stable considering the parameters of circuit componets: The output L-C filter of a step down converter contributes with 180 degrees phase shift in the control loop.
So using an higher voltage rating caps doesn't overload or hurt the circuit but using bigger caps can bring problem.

I have repaired a lot of SMPS, not for PC but for other application, and I have never had a single problem using caps with voltage value higher than the original one.
For increasing capacitor value ( uF ) I have read here that someone suggest to use bigger caps than the original one but, as I'm completely newbie on MOBO problem, I can't say if it is safe to do in this way, experienced members can judge better than me.

For sure if the circuit is engineered very well, it can accept different value because the engineers usually take some margins because they know very well that not always you find the right components for production, sometimes you must take what market offer. Moreover every company can change they products features if they want so you never know if tomorrow you can find the same component you are using today.

This is my last post on this argument, I think it is going on for nothing.

Gianni

[PCBONEZ]

Re: voltage difference limit?

Installing a capacitor with a higher voltage rating DOES NOT CHANGE THE VOLTAGE in the circuit.

.

[PCBONEZ]

Re: voltage difference limit?

If you check around ........

#1: You don't understand what you are reading.

#2: I don't need to check around. I was certified by DOD as an electronics tech in 1981. I worked on the electronic control systems for NUC plants at that time.

#3: MOST of the people trying to straighten you out in here are experienced electronics techs of one kind or another and many still do it for a living.

.

[chipper]

Re: voltage difference limit?

#1: You don't understand what you are reading.

#2: I don't need to check around. I was certified by DOD as an electronics tech in 1981. I worked on the electronic control systems for NUC plants at that time.

#3: MOST of the people trying to straighten you out in here are experienced electronics techs of one kind or another and many still do it for a living.

.

I understand what you are saying , but I have also not said that any circuit would be increased in voltage by adding a higher voltage capacitor to the circuit in itself. I said that I wouldn't recommend changing any capacitor to a higher voltage than what was originally installed on any circuit , due to the fact that much higher voltages are already set within a parameter when the original capacitors are installed or during designing. "If" there is any potential for the current to increase , it is with a higher rated cap , it can form in the higher capacitor , while it can't go nearly as high in the original capacitor.

If changing capacitors to higher voltages was a good practice , then much higher voltage capacitor installation would be part of a design characteristic. We are also talking about increasing all sorts of parameters when we change capacitor voltage , which can trigger protection circuits and shut down any circuit. Since I have applied this method , none of my circuits are down and none of them abnormally heat up. Switching supplies can actually create heat because the protection circuits are continuously reaching peak and shutting down , off and on. Heating and cooling , where if they were left alone , they would run normally without ever shutting down.

I have been looking into the possibilities and have concluded that alot of circuit "parts" can be operated from say 5 to 35 volts , but this is dependant upon the application of the part in a designed circuit. Which lead me to think in terms of the original circuit design parameters in general.

Overall , my theory has been applied and works without absolutely any adverse reactions , meanwhile , if I install higher voltage rated caps , I am seeing all sorts of irregularities , some of which , don't allow the component to start ( as a result of the protection circuit shutdowns ).

I keep wondering why a manufacturer or designer of any circuit , would put a 16v capacitor on a circuit that could normally function with a 35v capacitor in it's place. IE : If you compare a 1000uF x 16v cap with a 1000uF x 35v cap , the size is nearly twice as big , moving up to a 1000uF x 50v cap can double the size again. Which usually will not fit in certain applications anyways.

But if the board ever goes into any overload , the 1000uF x 50v cap is then capable of storing a 50v charge on a circuit that has parts on it that have a "maximum" limit of 35v. Moving up 2 levels can allow almost double the voltage to be present. In a 1000v overload , this could be serious , seeing as the components have a maximum limit of say 350v. Meanwhile it is switching and shutting on and off repeatedly by protection circuit designs.

I will let you know when I find problems in any of my circuits staying with the original voltages of caps , or any other part of a circuit. I absolutely would not increase the cap voltage on any power supply , that's why they work for so long , they didn't shut down at all. (ever)

Sure , others might , but when a power surge occurs , any cap beyond the maximum circuit voltage rating , is a killer. If it was normal , it would have just shut down once. Not switch on and off due to protection 5 times or more. (repeatedly). And my warranty will thank me - covered in 20yr old dust. In fact working within the installed parameters has lead me on a path that exceeds any description. After all , you can hook up lead wires to large caps and mount them elsewhere if you like , instead of in an allotted space.

And the radiation off of them alone , can give you a shock. Whatever , when in doubt , go with the designer. I think we can agree that larger caps have a bigger potential to hold heat within the main body of the cap , even though they can withstand more heat as well. Caps are always gone in the heated areas , sandwiched between something solid , having added to the temperature.

So much for relying upon the protection circuit to act accordingly. Like a dog in heat normally will? Ok , caps don't store voltage , they store energy according to a rating.

I had an arguement like this once with a forklift technician who claimed that I was all wrong about 36v (large forklift batteries). There was a reconditioned forklift running on a new battery and battery charger that kept dying after 4hrs. I told him this and he suggested the battery was not good. This was going to cost the company thousands , when I stepped in and said the battery charge rate and length of time has to be adjusted according to the amount of work the machine does. (how much weight it lifted) 2000lbs per lift. As opposed to lifting say : 500lbs per lift. Hour after hour continuously.

He argued on the phone to my supervisor that he knew best , but we set him up. We tried my theory and it worked. Then we staged an inspection of the whole forklift / charger and battery.

The tech comes in , replaces a few contact parts on the forklift about 3 times over in a month prior to this so : I applied my theory that if the battery is in a low state of charge - having been working at it's maximum capabilities , the charger must replenish the same workload. To do this : I charged the forklift battery for 4hrs. on an 8hr cycle timer - but I stopped the charger and unclipped the contact connnector and reset the timer automatically on "HIGH" charge for another 8hrs. Which ended up being a total of 12hrs. of charging , instead of 8. He said this was not possible on a 8hr. charger. Click , off it went and right back into high charge for a full 8 hrs. After that none of the contacts failed nor did the forklift - it ran for 8hrs. at full charge - lifting it's maximum 2000lbs for 8 solid consecutive hrs.

Needless to say the company was re-checking the bills for all the fees that were being charged and the tech was not pleased. I cheated though , because I had been doing that for over 15yrs. at the time with all the other forklift batteries I ever worked with - so I knew.

No work was done on the lift afterwards , nor did the battery die in mid stream like it had been. Diagnosed with bad control contacts 3 times over.
All this was done to a tech who couldn't hardly fit his head and shoulders under the warehouse man-door he was so tall. Needless to say -he really was not pleased. I was though , all my work was always done.

[chipper]

Re: voltage difference limit?

Let's see - the battery consists of 18cells x 2volts each = 36volts. When you pull the "state of charge" down low , what can occur? Charging - ya that's it charging.

So - with a 8hr. charger that has a "high" setting and a "low" setting - how do I make the charger replenish the charge lost? Charge it for 8hrs. which is the "normal" charging cycle and restart it again for say 4hrs. NO. It won't do it. It automatically senses the "state of charge" and applies the "low" charge setting and clips back 4hrs to compensate for the state of the charge.

Hmmmm : Why not interupt it while it's on high charge , unhook it - and trick it to reset the high charge cycle while the state is still low. Hey it works. Leave it alone.

[PCBONEZ]

Re: voltage difference limit?

>>> I said that I wouldn't recommend changing any capacitor to a higher voltage than what was originally installed on any circuit , due to the fact that much higher voltages are already set within a parameter when the original capacitors are installed or during designing. "If" there is any potential for the current to increase , it is with a higher rated cap , it can form in the higher capacitor , while it can't go nearly as high in the original capacitor. <<<<

-
It doesn't work like that -> end of story.

Capacitors of higher voltage rating than necessary are installed AT THE FACTORY in almost all equipment.

A higher voltage rating DOES NOT allow a capacitor to store more energy.
That is a function of the capacitance value.
Voltage rating has nothing to do with it.

.