Cyprus-Forum.com

[denizaksulu]

I have a noisy fan.
Will reducing the voltage (e.g. from 12V to 9V) reduce the speed, and therefore the noice?

It seems like it since:

P = V . I = F . v (Power = Voltage * Current = Force * velocity)

What do u think? Any advice?

Ball bearings.!

[Oracle]

WD40 ....

[Get Real!]

I just couldn't remember the word "Carbon" at the time so I improvised! But anyway, Carbon brushes are made by mixing Carbon with Copper for better conductivity so don’t assume its pure carbon being used just because they’re called “Carbon brushes”!

Remember now your not talking to Miltiades, thats not quite wright for all brushes. See here:-http://www.pic.co.th/material02.htm

You must be worse than Miltiades, you don't even read your suggested links.

In the manufacture of this material metal powder, principally copper, is added to the graphite.

[Get Real!]

Because we moved on from fans and were talking about food mixers and such!

I don't believe you, I bet you didn't even know brush less motors existed.

I've got quite a few brushless motors lying around here in my workshop but it’s the brainless Greeks I seem to have run out of…

You and Miltiades would make a fine pair, reminds me of Laurel and Hardy.

Brushless, brainless, pointless, you're all the same to me Yialousa...

[yialousa1971]

I just couldn't remember the word "Carbon" at the time so I improvised! But anyway, Carbon brushes are made by mixing Carbon with Copper for better conductivity so don’t assume its pure carbon being used just because they’re called “Carbon brushes”!

Remember now your not talking to Miltiades, thats not quite wright for all brushes. See here:-http://www.pic.co.th/material02.htm

You must be worse than Miltiades, you don't even read your suggested links.

In the manufacture of this material metal powder, principally copper, is added to the graphite.

You obviously can't read GR, you forgot to post the whole link.

Graphite and resin-bonded graphite, Letter F
Carbon brushes made of this material contain natural graphite with very small amounts of mineral constituents. The actual amount determines the level of abrasiveness (low medium) when the brush is in use.

Carbon, Letter H
The special merits of carbon brushes made of this material are toughness and hardness. Mixing in additional abrasive substances provides the carbon brush with an excellent rubbing effect, making it possible to use this material on flush mica insulation.

Carbon-graphite Letter L
Carbon brushes made of this material have the same mechanical toughness but generally a lower level of hardness compared to those made of carbon. This material also reveals a slight abrasive quality.

Metal-graphite Letters A,B, K and S
In the manufacture of this material metal powder, principally copper, is added to the graphite. This leads to a substantial reduction of the specific, electrical resistance. In practice typical resistance values lie between approx. 0.1 and 12 m W m

Due to the partly metallic points of contact between the surface of the brushes and that of the commutator there are relatively small losses during transition, even when high electric load are being carried. Commutator carbon brushes made of this material with a high metal content can only withstand a certain amount of stress. As a rule they are only used for low voltage motors with a terminal voltage of approximately 30 volts such as micrometers, motors for toys and first and foremost in automobile electric.

Key to the letters

A = Natural graphite +copper

B = Natural graphite + copper + lead

K = Natural graphite + copper, bound with pitch

S = Natural graphite + silver

Mixing Components
Exact composition of the brush depends on the application. Graphite/Carbon powder is commonly used. Copper is used for better conductibility (rare for AC applications and not on automotive fuel pumps which run on carbon commutators). Binders are mixed in so the powder holds its shape when compacted. (mostly phenol- or other resins, pitch). Other additives include metal powders, and solid lubricants like MoS2, SiO2. Much know-how and research is needed in order to define a brush grade mixture for each application/even for each motor.

Let me reimind you what you said:-

You said that the brushes were made of Soft Copper, I informed you of your ignorance ie. the brushes are actually made of Carbon not Soft Copper. Now instead of owning up to your ignorance, you tried to dig yourself out of the hole.

Now read my link above with the extra info. in quotes above and you will see that most Motors have Carbon brushes made of Carbon and all domestic ones.

More info here:-

http://www.repcoinc.com/carbon_brushes_fld/reference.asp

I think I owned your Arse tonight.

[Get Real!]

I think I owned your Arse tonight.

In the manufacture of this material metal powder, principally copper, is added to the graphite. This leads to a substantial reduction of the specific, electrical resistance.

You sure did...

Everything I posted about motors to Milti came straight from personal knowledge and experience whereas you couldn’t even present me with a worthwhile argument even after reading through a dedicated website on the subject, yet you had the audacity to ask if I’ve ever heard of brushless motors!

Write this on your forehead Yialousa to keep you from ever getting smart with GR again and making a fool of yourself…

“GR's little pinky is more knowledgeable than me and my family put together!”




Btw...

A = Natural graphite + copper

B = Natural graphite + copper + lead

K = Natural graphite + copper, bound with pitch

S = Natural graphite + silver

Still wondering if motor brushes contain copper?

[yialousa1971]

I think I owned your Arse tonight.

In the manufacture of this material metal powder, principally copper, is added to the graphite. This leads to a substantial reduction of the specific, electrical resistance.

You sure did...

Everything I posted about motors to Milti came straight from personal knowledge and experience whereas you couldn’t even present me with a worthwhile argument even after reading through a dedicated website on the subject, yet you had the audacity to ask if I’ve ever heard of brushless motors!

Write this on your forehead Yialousa to keep you from ever getting smart with GR again and making a fool of yourself…

“GR's little pinky is more knowledgeable than me and my family put together!”




Btw...

A = Natural graphite + copper

B = Natural graphite + copper + lead

K = Natural graphite + copper, bound with pitch

S = Natural graphite + silver

Still wondering if motor brushes contain copper?

What happened to the rest of my post? The most important part, the part with the info/types of Carbon Brushes/Graphite brushes, brushes with no added Copper, but you removed this to try save face. It was I that posted the above info, I never denied this because I posted the info, didn't I?

Now again most (if not all) brushes used in domestic motors use Carbon/Graphites types not Metal-Graphite types. As to your experience is that motors in toy cars, is that why you thought they were made of Soft Copper because they brass coloured. See below!

Metal-graphite Letters A,B, K and S

In the manufacture of this material metal powder, principally copper, is added to the graphite. This leads to a substantial reduction of the specific, electrical resistance. In practice typical resistance values lie between approx. 0.1 and 12 m W m

Due to the partly metallic points of contact between the surface of the brushes and that of the commutator there are relatively small losses during transition, even when high electric load are being carried. Commutator carbon brushes made of this material with a high metal content can only withstand a certain amount of stress. As a rule they are only used for low voltage motors with a terminal voltage of approximately 30 volts such as micrometers, motors for toys and first and foremost in automobile electric. Since the graphite part is responsible for the gliding quality every effort is made, while bearing in mind the electrical losses, to keep the content of metal in the material to a minimum.

Again you do not know what you are talking about since you said Carbon bushes are made of Soft Copper, which i corrected your ignorance. Next time do not remove parts of my post to say something I didn't.

[yialousa1971]

Any current not going to the fans must be emitted as heat via a resistor so you've basicly increased the heat inside the case.

I am not an expert in this field but I can't understand your theory here. If there is less demand for energy doesn't this mean that less energy will be consumed? The way you say is like the power supply always takes the same amount of energy regardless of how much energy the devices of the computer consume and then turns the surplus into heat. That can not be true because I know for a fact that on a laptop you can save energy and make the battery run longer by having your hard drives spinning slower or making your LCD dimmer!

To simplify things we need to stick to analog electronics and take a dimmer switch, which is the same as a normal switch except it has a variable resistor (the knob you turn). As you rotate the knob anticlockwise the resistance is increased and so the current going to the light bulb is decreased thereby making the lamp fade but this “stolen” current has to go somewhere and it is dissipated in the form of heat using a component like a ceramic resistor.

Every component has a preset wattage or power consumption and the only way to decrease that power usage is to “steal it” via a resistor (to resist a portion of that current) which makes the resistor heat up to dissipate that wattage. The whole power requirement of that component is still being consumed but a portion of it redirected to a resistor. The ACPI used in laptops is a different technology altogether.

This is the biggest load of bull I've ever heard. The higher resistance the lower current flow, when you increase the resistance the current doesn't flow, just like turning a valve controlling the flow of water. Resistors are used to control the flow of current or as potential dividers. You do not "steal " anything, a resistor is put in series with the circuit/componet you wish to supply, the higher the resistor the smaller the current will flow. You don't have to "steal" anything, you use resistors to control what Current you want, like a tap. I=V/R, Ohms law. As for "Every component has a preset wattage or power consumption ", wrong components are Rated, they do not have a present wattage, they are Rated!

[yialousa1971]

Any current not going to the fans must be emitted as heat via a resistor so you've basicly increased the heat inside the case.

I am not an expert in this field but I can't understand your theory here. If there is less demand for energy doesn't this mean that less energy will be consumed? The way you say is like the power supply always takes the same amount of energy regardless of how much energy the devices of the computer consume and then turns the surplus into heat. That can not be true because I know for a fact that on a laptop you can save energy and make the battery run longer by having your hard drives spinning slower or making your LCD dimmer!

Ignore GR, you are wright here. The power consumption is P=I x V, so if R (resistance is high) I (current) will be low. Turn off the hard drives then they are using no power, it's as simple as that.

[Get Real!]

Any current not going to the fans must be emitted as heat via a resistor so you've basicly increased the heat inside the case.

I am not an expert in this field but I can't understand your theory here. If there is less demand for energy doesn't this mean that less energy will be consumed? The way you say is like the power supply always takes the same amount of energy regardless of how much energy the devices of the computer consume and then turns the surplus into heat. That can not be true because I know for a fact that on a laptop you can save energy and make the battery run longer by having your hard drives spinning slower or making your LCD dimmer!

Ignore GR, you are wright here. The power consumption is P=I x V, so if R (resistance is high) I (current) will be low. Turn off the hard drives then they are using no power, it's as simple as that.

Do you know the difference between an electronics COMPONENT and an electronic or electro-mechanical DEVICE?

Therein lies your problem!

Components: Motors, light bulbs, capacitors, resistors, torroids, etc.

Devices: HDD, FDD, DVD player, Memory card reader, etc.

The ACPI (Advanced configuration and power interface) is power saving technology for DEVICES not components!

Now stop posting rubbish!