Heatsink F5T

[Feckie]

Thinking up the next project. Considering both water cooled or passive but whatever it comes to, i want it to be unique. The easy or hard way for now is irrelevant.

Picture an F5T V3 in an upright octagon with a 20cm fan at the top.

Each PCB will have its own heatsink.

So would one of these be enough, the fan will only be going at an absolute minimum also.

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[AndrewT]

20cm (200mm) fan is quite big.
Where do you get them?

Is a small fan motor (say 80mm fan) capable of starting and running at low speed, with a much larger fan attached?

 

[AndrewT]

That sink is very expensive.

Heatsinks usa are much better value.
But carriage to Ossie is probably too expensive.

 

[Feckie]

20cm fans are available for pc cases. They can move at speeds relatively low.

Antec BIGBOY200 Tricool BIG BOY 200 Case FAN 20cm 100177344638 | eBay

As for the price, i was really only looking at the heatsink size. I'm sure i can get cheaper prices.

 

[AndrewT]

Thanks for that.
Found one in the UK for £9.35 incl free postage.

 

[Feckie]

So do you think the heatsink would work?

 

[AndrewT]

It may work.
Try some form of speed control. very slow for cooler conditions and slow for warmer conditions.
Ensure that the motor starts reliably. Using a resistor to control speed is very easy to end up with a stalled motor that does not run.
Voltage control is far better than resistor control for speed adjustment.
But voltage needs a spike to get the motor started. Maybe you can use the speed monitor output to check for turning.

Pulse width control is good, but it is very likely to interfere with audio, unless you are careful to attenuate the interference.

 

[Zen Mod]

.

 

[AndrewT]

If I read that correctly it is resistor speed control (the FET = resistor) with a start up pulse.

Please confirm?

 

[Zen Mod]

isn't that obvious ?

 

[Feckie]

Could just use one of these, this just an example there are single controllers around... In fact I think I have one somewhere

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[Zen Mod]

certainly yes

 

[AndrewT]

.pic from post 8

If I read that correctly it is resistor speed control (the FET = resistor) with a start up pulse.

Please confirm?

isn't that obvious ?

The fact that your back to front confirmation effectively says I did read it correctly then that means it is obvious, since I got it.

But I just needed someone to say: yes, that is what it does.

 

[Andersonix]

Picture an F5T V3 in an upright octagon with a 20cm fan at the top.

For best air turbulence, you want the fan to blow directly on the HS (as opposed to pulling through the HS) while also not opposing the natural upward warm air rise. So, fan should be at the bottom blowing upward. Placing the fan centrally at the bottom might also block some fan noise...

 

[AndrewT]

fan to blow directly on the HS (as opposed to pulling through the HS)

I don't think this applies.
Turbulent flow occurs as the speed of flow increases changing flow from laminar to turbulent.

Flow stream breakers can make the flow turbulent at slower speeds.

 

[Feckie]

Flow stream breakers can make the flow turbulent at slower speeds.

When you are referring to flow stream breakers, would having the psu's and transformers in the centre act as a breaker?

 

[AndrewT]

little bumps/fins etc can act as flow stream breakers.
Sharp/abrupt corners where they force the air stream to break away from the surface also do similar.