Pwm silliness

Way to much disregard of common sense and logic here to even try talking / explaining all the many reasons pushing 12v fans to higher than 13.2v is an invitaton to disaster, more wiriing overheating and shorting out (has nothing to do with impeller moving more air) to impeller not design to run at 25-40% higher speeds.

Everyone is telling you the same thing, it's not a good idea and therefore should not be consider in any way, shape or form . Thread title 'sillyness' sums it up .. sillyness can kill.
 
Common sense & logic would have bees walking from flower to flower.

Ok, 13.2v is perfectly fine, but hooking it up to my car wiring @ 14.7v will have my car looking like the bridge of the Enterprise right after "Shields are Down" is announced. ?
 
You can do it, but do note that the power goes up quite a bit as you're increasing voltage and current. Also, I think he used non-pwm fans, so you may run into more risk than him as far as electronics, and the increase in current and operating speed means more heat and wear on the coils, bearings, and just about everything else. A few of his fans (one zalman and a couple other noname brands) failed at 18v

Good luck!
 
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honegod said:
Common sense & logic would have bees walking from flower to flower.

Ok, 13.2v is perfectly fine, but hooking it up to my car wiring @ 14.7v will have my car looking like the bridge of the Enterprise right after "Shields are Down" is announced. ?
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Failure may not be instant or catastrophic, no. But it will occur.
 
honegod said:
Common sense & logic would have bees walking from flower to flower.

Ok, 13.2v is perfectly fine, but hooking it up to my car wiring @ 14.7v will have my car looking like the bridge of the Enterprise right after "Shields are Down" is announced. ?
Click to expand...

Car electronics are designed to a different set of specs: 14.6v +/-15% (12.4-16.8). That's because starting batteries supply 12.6v and need to be fed at least 13.2v to keep them topped off. In order for the alternator to supply enough current to charge a low battery and still run all the things that a car has (lights, ECU, radio, etc), 14.6v was chosen as the nominal output voltage to accomplish that.
 
Nobu said:
You can do it, but do note that the power goes up quite a bit as you're increasing voltage and current. Also, I think he used non-pwm fans, so you may run into more risk than him as far as electronics, and the increase in current and operating speed means more heat and wear on the coils, bearings, and just about everything else.

Good luck!
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Logarithmic style rather than linear increase kinda thing, aye.

It looks like the primary problem is the electronics portion, the control part.

The fan motor should be essentially the same as a 2 wire fan, yes ?

It would be cool if there were a step down thing to drop the 12v input to 5v that the circuitry uses, then i could just run a 5v from the psu to run the controller @ rated voltage while cranking the motor voltage itself up.
 
doyll said:
Way to much disregard of common sense and logic here to even try talking / explaining all the many reasons pushing 12v fans to higher than 13.2v is an invitaton to disaster, more wiriing overheating and shorting out (has nothing to do with impeller moving more air) to impeller not design to run at 25-40% higher speeds.

Everyone is telling you the same thing, it's not a good idea and therefore should not be consider in any way, shape or form . Thread title 'sillyness' sums it up .. sillyness can kill.
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everyones that is telling then seems to just bee telling stuff they have never worked with. its funny how some people with no experience want to tell about stuff they never tried.
Just because ppl say something does not mean there is any validity in it.

https://en.wikipedia.org/wiki/Argumentum_ad_populum
In argumentation theory, an argumentum ad populum (Latin for "argument to the people") is a fallacious argument that concludes that a proposition must be true because many or most people believe it, often concisely encapsulated as: "If many believe so, it is so."
its a commoan false logic a mongs people that dont tend to work in any scienticifc way.

now instead of people would provide som real emperical data that would be nice but simple opinions and guesses does not matter in physics


All my FAN oc has successful results albait i didn't have them for a long time because they got replaced.

Heck i might just go oc some more fans jsut to shut people up
 
SvenBent said:
everyones that is telling then seems to just bee telling stuff they have never worked with. its funny how some people with no experience want to tell about stuff they never tried.
Just because ppl say something does not mean there is any validity in it.

https://en.wikipedia.org/wiki/Argumentum_ad_populum
In argumentation theory, an argumentum ad populum (Latin for "argument to the people") is a fallacious argument that concludes that a proposition must be true because many or most people believe it, often concisely encapsulated as: "If many believe so, it is so."
its a commoan false logic a mongs people that dont tend to work in any scienticifc way.

now instead of people would provide som real emperical data that would be nice but simple opinions and guesses does not matter in physics


All my FAN oc has successful results albait i didn't have them for a long time because they got replaced.

Heck i might just go oc some more fans jsut to shut people up
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Yeah, practice what your preaching instead of being hypocritical.

You are correct, just because you say things doesn't mean you have experience, but I if you wnat to tell us things without having experience that's okay.

Some of us are posting experiences and sound suggestiions based on years of experience and education in physics, electrical and electronics fields instead of using wiki to come up with Latin put-downs in an attempt to valid ourselves.
 
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I've burned up lots of electronics in my days. But I always tried to understand the risks and accepts the consequences.

Things are manufactured to a design specification. Manufacturers are not going to design something to reliably operate in conditions 50% greater than some nominal point unless 1) it's expected that conditions may normally be 30 or 40% off, or 2) it's cheaper to do so with already available parts (e.g. a quad-amp rated for 32v).

I'm certainly not telling anyone not to give it a shot, but when they basically ask "What could go wrong?" I'm not going to say "eh nothing, reallt. Don't worry about it."

In this particular case, there's a lack of understanding of how things work. It's not just heat that is a problem, electron behavior in response to higher voltages can damage the microscopic structures that dictate how a circuit functions. Then there's the fact that in a PWM controlled PC fan, the motherboard doesn't source the voltage for the PWM signal, it sinks it. So now the motherboard components that control the PWM signal have to sink a 17v signal instead of a 12v signal. The tach circuit could be affected.
 
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ryan_975 said:
But I always tried to understand the risks
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I believe that is the point of this thread, to find out what the problem is.

The circuitry that daintily handles the signal stuff operates a big relay (mosfet ish) that actually switches the fan motor current.

No i do not want to mess with that side, just the fan power.

Surely the controll power is not taken from the pulsed dc so it must get its juice elsewhere.

Wouldn't even the 12v directly before the mosfet experience ugly pulsation caused by the current surges ?

I am thinking there must be something that cleans up the electronics power in a seperate loop kinda thing.

So... Feed a nice steady 12v into that seperate loop to keep the 'tronics all happy and freely tweak the motor juice as seems prudent. Maybe add cooling to the motor & bearings.
 
On a PWM I wouldn't even bothering messing with it due to the fact that the control board is part of the fan.
 
noxqzs said:
On a PWM I wouldn't even bothering messing with it due to the fact that the control board is part of the fan.
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Just about every modern brushless DC fan for the PC has a control board embedded in the motor hub, PWM or not.


I found the datasheet for the control IC found on a fan supplied with Intel CPU heatsinks. The motor coils are powered directly by the chips output pins. This particular IC had a max Vcc of 17v, while other ICs in the same family had a max Vcc of 21v. So it really depends on who made the fan what components they went with in their design.
 
ryan_975 said:
I found the datasheet for the control IC found on a fan supplied with Intel CPU heatsinks. The motor coils are powered directly by the chips output pins. This particular IC had a max Vcc of 17v, while other ICs in the same family had a max Vcc of 21v. So it really depends on who made the fan what components they went with in their design.
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Was going to look it up myself (I knew someone had it somewhere, I had read it before for something else), but didn't have time.
 
I am thinking that the pulsed current will act in some ways as AC does.
Yes, the 12v from the mboard is nice & stable BUT the current cannot be, because of pwm.

What effects of pulsed current could effect the delicate precision of the pwm circuitry ?

I am thinking caps to smooth out the power taken from the surging and ringing fan power, kind of thing.
 
honegod said:
I am thinking that the pulsed current will act in some ways as AC does.
Yes, the 12v from the mboard is nice & stable BUT the current cannot be, because of pwm.

What effects of pulsed current could effect the delicate precision of the pwm circuitry ?

I am thinking caps to smooth out the power taken from the surging and ringing fan power, kind of thing.
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On PWM fans all power enters fan from pin-2, including the power used to run the PWM circuitry. So if you supply your PWM fan/s with more than 12v you are also supplying the PWM cirucuitry with more than 12v.
 
doyll said:
On PWM fans all power enters fan from pin-2, including the power used to run the PWM circuitry. So if you supply your PWM fan/s with more than 12v you are also supplying the PWM cirucuitry with more than 12v.
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Yes, i understand that bit now.

But i am sure that all of the CURRENT to spin the fan does not have to go entirely through the control circuitry to get to the fan motor.

I am visualizing a big wire coming off pin 2 going to the input of the switch thingy, to be turned off & on as the control dictates, with a much smaller wire ALSO coming from pin 2 carrying the current needed for the controller to decide when and how long to flip the switch thingy.

Not literal wires, most likely traces.

So cut the trace of the thin wire, attach a seperate wire going to 12v, and vary the big wire voltage.

Not that i have any clue where this stuff IS on the board.

I just ordered a dc to dc variable step up converter and 3 cheapo pwm fans.
When they get here, from china, experimentation commences.
 
honegod said:
Yes, i understand that bit now.

But i am sure that all of the CURRENT to spin the fan does not have to go entirely through the control circuitry to get to the fan motor.

I am visualizing a big wire coming off pin 2 going to the input of the switch thingy, to be turned off & on as the control dictates, with a much smaller wire ALSO coming from pin 2 carrying the current needed for the controller to decide when and how long to flip the switch thingy.

Not literal wires, most likely traces.

So cut the trace of the thin wire, attach a seperate wire going to 12v, and vary the big wire voltage.

Not that i have any clue where this stuff IS on the board.

I just ordered a dc to dc variable step up converter and 3 cheapo pwm fans.
When they get here, from china, experimentation commences.
Click to expand...

In a simple implementation, you're pretty close. Pin2 would supply a transistor and a pull-up resistor. Current through the transistor would power the motor coils; the resistor would feed into the gate of the transistor (turning it on by default) and the PWM pin going to the motherboard or fan hub.

On the Intel fan I mentioned above the switching logic and motor current supply is internal to the fan controller IC; though there is a bit of support circuitry surrounding it you could probably hack into if you knew how it would affect everything inside the chip (a change in one part of an RC network changes the behavior of the whole network).
 
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