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Old 19th January 2011, 11:12 PM   #10011
labjr is offline labjr  United States
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Quote:
Originally Posted by Kilroy View Post
Thanks for this!
So I'm sold on the HS USA sinks but I'm trying to figure out what length I need for each side of the stereo amps.
Do you guys think 8" is enough or do I need to go all the way to 12" like Labjr did?

Thoughts?
Well, Nelson recommends 96 sq in. per channel so I added a little more to be sure since I don't know how this particular heatsink will perform. I imagine a 10 in piece would be sufficient. I believe somewhere back in this thread someone tried a 7 inch piece of the same stuff and thought it ran a little hot.
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Old 20th January 2011, 12:28 AM   #10012
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http://www.cooperbussmann.com/pdf/28...e536281e0a.pdf

Specs for fuses
It take times fo them to blow depending on the current

Supose 20 V rails and a mosfet Blow
You need the fault loop impedence to find out the fault current.

0.47 R the resistor on the source + wiring iside the amp + resistance of the power cord +resistance of the wiring inside the house+ resistance of the wires from your fuse board to the earting point of the distribution system.

say total impedence of the circuit 1 ohm 20V / 1 =20 A

You put the termistor on the ground to reduce ground loops ad the resistance to that and recalculate
Pick your fuse and folow the curve to where those 20 A cross the time.

I think you seen the wires on the coil winding on the speaker.

If you shure it will take it fine
If you don't know and don't care fine again.

On the third hand if you don't know and prefer to be safe ask.

Thats what I did and for shure a mosfet is faster than a fuse.



Will they take it fo that long
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Old 20th January 2011, 12:39 AM   #10013
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http://www.diyaudio.com/forums/attac...-sinks-001.jpg

My sinks black anodised now

300X400x83

But I got 4 ohms speakers and may build B2 or aleph once I have finished the F5 balanced
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Old 20th January 2011, 11:45 AM   #10014
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Quote:
Originally Posted by Kilroy View Post
Thanks for this!
So I'm sold on the HS USA sinks but I'm trying to figure out what length I need for each side of the stereo amps.
Do you guys think 8" is enough or do I need to go all the way to 12" like Labjr did?

Thoughts?
My heatsinks in cm are 150*350 and the fins are 50mm. With 1.4 amp on each mosfet it get warm, but not hot. I use raw aluminum.

D.
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Old 20th January 2011, 11:56 AM   #10015
AndrewT is offline AndrewT  Scotland
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Default typo?

Quote:
Originally Posted by Nikon1975 View Post
My heatsinks in cm are 150*350 and the fins are 50mm. With 1.4 amp on each mosfet it get warm, but not hot.
I can see they never get hot !
150cm*350cm would need a crane to install them.

What size are the fins? 350*50 or 150*50?
Are they aligned vertically for best air flow?
How thick is the backplate?
How have you attached the FETs to the heatsink?
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Old 20th January 2011, 12:07 PM   #10016
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Sorry mm. What I wanted to say not inches.

Fins are vertically aligned.

D.
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Old 20th January 2011, 01:28 PM   #10017
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Quote:
Originally Posted by Nikon1975 View Post
My heatsinks in mm are 150*350 and the fins are 50mm. With 1.4 amp on each mosfet it get warm, but not hot.
Small wonder.
Reads like a very nice heatsink.
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Old 20th January 2011, 01:37 PM   #10018
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it's the biggest that conrad has. 0.2 C/W if I remember well.

D.
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Old 20th January 2011, 01:51 PM   #10019
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Quote:
Originally Posted by Bksabath View Post
Neutrality yes it may be but then you have loads of energy stored in the caps

Is the may be that scare me.
Don't you use to put bleeder resistors?
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Old 20th January 2011, 02:04 PM   #10020
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Quote:
Originally Posted by Bksabath View Post
Tanks Neutrality

OK thats fine then

What the time response for the fuse say for example rated at 3A and the fault current is
say 30A ?
Look for the exact brand and model of the fuse and see it in their datasheet.
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