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Old 6th October 2008, 04:57 PM   #1
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Default Advise on heat sink

Hi everybody. I have a question. The heat sink I can find here is 150 (h) x 100 (w) x 25mm (d). I intend to mount the mosfet onto the heat sink. Please see attached images. Will this be enough? These heat sink are from China and o specs on them. Please help.
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Old 6th October 2008, 05:04 PM   #2
AndrewT is online now AndrewT  Scotland
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how much heat do you need to dissipate?
What temperature is acceptable at the FET case?
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Old 6th October 2008, 05:10 PM   #3
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Thanks for reply. I would like to have the case at 55c. This is A5 mono.
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Old 6th October 2008, 05:16 PM   #4
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Maybe you can try to mount a resistor and plot the temp rise at various point with some thermometers.
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Old 6th October 2008, 05:19 PM   #5
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Think 1.5C/W for a single of those 150mm/6" heatsinks.
So 2 rows of 4 heatsinks should be able to handle the 150W.

It's not such a bad idea to use those sleek heatsinks, if you don't mind the 40cm/16" depth of the amp.
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Old 6th October 2008, 05:23 PM   #6
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I haven't got the heat sink yet. They are expensive and I can't afford to experiment with trial and error. These are the medium size heat sink, the bigger size ones are way too large and the smaller ones is a bit too thin.
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Old 6th October 2008, 05:27 PM   #7
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Then estimate the C/W number with a thermal resistance calculator.
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Old 6th October 2008, 05:30 PM   #8
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Thanks, I do not mind the 400mm depth at all. So, these heat sink should be able to handle the heat. Thanks for the help. I will go ahead with the plan.
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Old 6th October 2008, 05:36 PM   #9
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Quote:
Originally posted by pmchoong
So, these heat sink should be able to handle the heat.

NO! What people have told you, is based on guessing. To you it should translate into something like:

"Those heatsinks are worth checking out a bit closer, and do some calculations."


As Jaccolina stated above, there are online dissipation calculators around, and if sucha a calculation tells you that the heatsink is big enough, well, then it's a bit closer to a green light.


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Old 6th October 2008, 05:46 PM   #10
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Quote:
Originally posted by Magura



As Jaccolina stated above, there are online dissipation calculators around, and if sucha a calculation tells you that the heatsink is big enough, well, then it's a bit closer to a green light.

Magura

Dissipation calculators? Please pardon my stupidity, I do not know how to use these calculators. The maths involved is too complex.
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