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Old 19th January 2011, 01:16 PM   #9981
tinitus is offline tinitus  Europe
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noone yet tried to measure temperature of heat radiation, in millimeters from heatsink ?

Im quite sure that even a few millimeters will make a difference
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Old 19th January 2011, 02:16 PM   #9982
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Just brilliant bit-by-bit going trough each aspect with fine combed.
Rod site is really good and easy to understand tanks for the find.

Udailey as you posted the data
What is the heat propagation on different metals meaning how easy is for heath to travel across
I think that Cooper is about 2 times as good as aluminium but I may be wrong could you help.

I was looking at mounting options and I am going to try something similar to the picture
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Old 19th January 2011, 02:21 PM   #9983
dazed2 is offline dazed2  Canada
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Quote:
Originally Posted by AndrewT View Post
I see 0.7C/W for 3" long profile for HeatsinkUSA.
A 12" length should be about half of this, i.e. 0.35C/W

I cannot see any spec for Parmetal.

I expect that HeatsinkUSA can dissipate a lot more heat than ParMetal
The Specs for ParMetal are at the bottom of the page.
When I called them they said that the data there was measured data, not theoretical. The quote it in C/W/inch.


Also if I'm reading Udaily right, I should paint the heatsink with black oil? Wow. I didn't know that. When I called Par-Metal they had the option of anodizing...

Last edited by dazed2; 19th January 2011 at 02:23 PM.
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Old 19th January 2011, 02:53 PM   #9984
labjr is offline labjr  United States
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I haven't finished it yet but I bought 2 twelve inch pieces of the Heatsink USA 10 inch profile for my F5. Maybe more than I need. It's pretty hefty stuff at about 12 pounds each. Better too much than not enough. Also looks a bit nicer in person than it does on his website. Made in USA too. Not sure about Par-metal.
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Old 19th January 2011, 02:55 PM   #9985
udailey is offline udailey  United States
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Not black oil but an oil based paint that is black. Well, thats Rod's information.. I just spit it back out here. He says black oil paint very very thin is the best but that anodizing is good to, you can see on his graphs. I would go for the anodizing option but then again you would still be buying a sink that cant compete with HS USA sinks. Honestly in the USA the HS USA guys have the best deal that I can find and the extrusion is made, in my opinion, especially for Pass DIY efforts. Its just my guess but I am betting Russel started his business to take care of us.
Copper spreads the heat the fastest but it doesnt like to LET GO of the heat. Aluminum spreads it pretty fast as well AND dissipates. Aluminum is best in a sink. You want to use a heat spreader? Probably copper is best but I would use some sort of thermal paste to help get the heat from the copper over to the aluminum and you will find folks telling you that copper on top of aluminum causes some sort of chemical reaction and I forget what else happens but two odd metals touching for a long time has some chemical reaction that has been discussed here before. I think if you use the paste you might not worry so much about this reaction.
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Old 19th January 2011, 03:10 PM   #9986
osscar is online now osscar  Latvia
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how many F5 are built on these 10 000 posts ?
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Last edited by osscar; 19th January 2011 at 03:12 PM.
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Old 19th January 2011, 03:14 PM   #9987
labjr is offline labjr  United States
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I thought I read that copper is not only a better conductor and for the same reason dissipates heat better. The biggest disadvantage is cost.

Putting the two metals together causes a galvanic reaction which causes corrosion. Sort of like chewing on an aluminum gum wrapper.
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Old 19th January 2011, 03:25 PM   #9988
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Hi

I built an F5 a while ago using Panasonic TSUP 18000UF caps. I have just spotted what appears to be a good deal and wondered if anyone has used these with their F5

Vishay 15000UF 25V (Part no. MAL205656153E3)

I have attached the data sheet.

[IMG]Click the image to open in full size.[/IMG]
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File Type: pdf 15000uf.pdf (140.2 KB, 19 views)
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Old 19th January 2011, 03:51 PM   #9989
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Tanks udailey

2 different metals in contact chem reaction very good point and need looking at.
Yes heath spreaders it will be.

As 4 ohms speakers loads off currants.

Heath sink I have found this new product in Farnell 1315296
Graphite based so is conductive eletricaly good enoug between sinks and heath spreaders not so on the mosfets.

Thermal conductivity 10.5 W/mK what ever that means.
And red Kerafoll

While here could you help with speakers protection?
To fix a broken amp no problem
to replace speakers money and no music for a while. I could survive that.
To have her say I told you so priceless.
Options are quite a few

Fuses but signall degradation and slow
There is a few around based on low pass filters (nuisance tripping) and there use to be a few dedicated IC now obsollete so ..

I was thinking as AC signall by its nature crosses the zero line voltagge to make a detector that (say ipoteticalicamente Just positive side for semplicity)

Rising edge start a timing circuit when signal return to zero reset the timer

IF there is DC offset or one of the mosfets blow the signal will stay hi and the timer will latch and operate a relay disconecting the speakers same for negative branch.
But relay are not so good with DC as arking between contacts and also compromise signall when connected in series with the speakers
Ten maybe a Mosfet operated as swithc after the capacitors bank when the circuit detect a fault it will stop conducting disconnecting the suply.
Much faster than a relay.

I am stuck with the timing circuit as maybe it need to be 100 or maybe 20 milly seconds
question about mosfet
What is the heat load / disipation for mosfets as switch (saturation region)
I believe it is much less than when in the linear region as in saturation region resistance seen is much lower?

If so It may be possible then to use one as swithc with say full rail voltagge at say 3 / 4
A and use this to disconnect the suply to the amplifier after the capacitor banks.

Help please.
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Old 19th January 2011, 04:06 PM   #9990
AndrewT is offline AndrewT  Scotland
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Quote:
Originally Posted by dazed2 View Post
The Specs for ParMetal are at the bottom of the page. They quote it in C/W/inch.
that is not Rth s-a.
Rth s-a in C/W is not inversely proportional to the height of the heatsink.
The numbers quoted at the bottom are nonsense.
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