Stealth LED Array light .

[stardustsailor]

Back to the heatsink ...
Drilling time ...

But before that some "careful" drawing ..

Remember one the 'gold rules ' of an efficient HSF cooling system ?

"The coldest part of air ,to the hottest part of heatsink "



Or vice versa ..
The hottest part of heatsink 's fins ,underneath the coolest part of fan blown air stream ....

Wiring ,this time ,will be done through the heatsink ...


Cheers .

 

[Mohican]

So precise

 

[stardustsailor]

Now ,Let's go to the rear panel ....

The rear panel and it's components (wiring is missing ) .



The pins protruding from the 'through-hole' parts ,have been trim- cut ..
( MeanWell PS-05-12 CV fan power supply )




And then board is sprayed with Teslanol T7 ,an water-resistant ,isolating lacquer .
Film of thickness 25 microns ,isolates up to 22 kV .



This part (circular contact ) will be cleaned again ( with IPA or Acetone or Paint Thinner ).
This contact has to be grounded.



..An idea of the placement ....





Cheers.

 

[stardustsailor]

Well ,parts are placed in the rear panel....
So far ,so good ...

Cheers.

 

[stardustsailor]

So precise

Nooootttt soooo precise ,but it will do ,anyway !

 

[stardustsailor]

The rear panel it's all wired up !


There's a connector for the fan ,as also three connections for powering/ grounding the rest of the fixture ...
( AC-N , AC -L & Ground/Earth - Used Crimp connectors with 'female' end and 'male' adaptor also )


And a test ...



Cheers.

 

[bicit]

And then board is sprayed with Teslanol T7 ,an water-resistant ,isolating lacquer .
Film of thickness 25 microns ,isolates up to 22 kV .

Is this a electric shock safety precaution? Or for protection against ambient humidity?

 

[stardustsailor]

Is this a electric shock safety precaution? Or for protection against ambient humidity?

Both...

 

[bicit]

Both...

I'll have to keep this in mind. I'm not sure how to word this exactly, but how much water resistance does a coat like that offer? Just corrosion protection? Or will it actually protect against water droplets?

I guess I could google it... but wheres the fun in that.

ETA: I love your build threads btw. Always manages to plant a few idea seeds.

 

[Mohican]

Hey Stardust - Have you seen this site about heat sinks?

http://www.smps.us/thermal.html


Cheers,
Mo

 

[Mohican]

I found it when I searched for a placement calculator for heat sinks.

 

[churchhaze]

There's a free tool called r-tools that crudely lets you simulate different profiles with different parameters. Problem is you have to sign up to use the tool.

Here's an example of how the simulation looks. You can have multiple heat sources, each with their own area, location, and wattage.

 

[Mohican]

I occurred to me that the heat from each COB will be additive between the two locations and would require more distance between them.

Like this:





Cheers,
Mo

 

[stardustsailor]

I'll have to keep this in mind. I'm not sure how to word this exactly, but how much water resistance does a coat like that offer? Just corrosion protection? Or will it actually protect against water droplets?

I guess I could google it... but wheres the fun in that.

ETA: I love your build threads btw. Always manages to plant a few idea seeds.

Look ..
It does not pass as an IP xx grade water proofing ....

It can protect from either moist or even droplets ...
(tested)
..

Still it's nothing like a 'full epoxy boxed' circuit board ..
Good thing is that allows for service/repairs to the board ...

In the case of a full epoxy enclosed board ,once a capacitor 'swallens' ,( ~1 to $5 to replace ) ,
you throw away the whole driver/psu ( several $$ ) ....

 

[stardustsailor]

I occurred to me that the heat from each COB will be additive between the two locations and would require more distance between them.

Like this:





Cheers,
Mo

Mo ,you just moved the heat sources ,away from coolest point of the heatsink-fan system ...
They can be so close together ,say touching each other ..So close ..
Like if they were one single heat source ...
That close ...
As long as they are placed on the coolest point of the HSF ...

In fact you 've just decreased system's cooling efficiency by approx 30% ....


A good idea is not to place the cxa in the same 'axis ' ..
Air stream enter the heatsink fins in a complex 'twirling' motion ,rather just straight downwards ..
The cxas could be placed -respectively to the twirling motion's direction ,given by the rotor - "off axis" .
That way , maybe an increase of x% in convection ,might be possible ...

 

[stardustsailor]

Although ,ideal placement would be ,on on the top right part of wing area and the other on the bottom left .
There the stream enters the fins 'parallel' thus resistance is low ...

Where I've placed currently the two cxas ,the air stream enters the fin area ,'meeting ' the fins perpendicularly ,
like when hitting a wall ...That creates turbulance there ,and thus resistance and thus reduced convection ....

At this example of HSF ,the highest convecting fin areas ,are the one on top right and the one on bottom left ,
if the twirling motion of the downward stream has an anti- clock-wise direction ..
(at pic we see an 'X-ray' graph ,facing the base of the heatsink )


So ,underneath those areas is the highest convecting point to place the led arrays ...


Cheers.

 

[salmonetin]

jejeje drivers nude pics, its nice see drivers inside look,

saludos

 

[stardustsailor]

Well ,I'm still learning...
..

Cheers.

 

[Mohican]

Found this PhD paper on Heat Sink physics. I am still searching for one that discusses placement of multiple heat sources.

http://etd.lib.metu.edu.tr/upload/12605700/index.pdf

Cheers,
Mo

 

[Mohican]

Page 32 on this one has the modeling equations for multiple sources:

http://upcommons.upc.edu/pfc/bitstream/2099.1/14262/1/Heat Sink analytical modeling PFC Joaquim Guitart Corominas.pdf


Cheers,
Mo