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Old 21st March 2012, 09:30 PM   #1081
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have to say i agree with that
15mm base might be a good one for class A with some depth.(and split sinks)
or some 10mm heatsprader on 10mm base maybe. this is a guess.
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Old 21st March 2012, 09:44 PM   #1082
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Heath spreaders
why did I not....?

Yeah You wanna Turbo you need intercoolers as well.

While you there and fix heath spreaders there is a bit of it that I like but may not be that plain to see.

Instead of using silly M3 (sorry for metric) screws with the danger of stripping the treads why not use captive bolts with the heads buried in the spreader
then clamp the mosfets with a bar and nut and washers on outside
This way one can use M4 or larger screws put much more pressure on the mosfets than a single screw would.

especialy if one use Kerafoll this give a much reduced heath Impedence
between mosfet body and the rest of the cooling system

If you can afford it get same cooper (or hunt around for scrap)
The radiated heat is lower than Aluminium (as cooper is mirror like) but the Thermal conductivity is mucho larger (twice ?)

Your sink will run much hotter but the mosfet will be cooler.

On soft start

If any one needs it I got momentary switch to operate a single transistor relay that puls inn the main Trafo trough 2 CL60 in series then the CL 60 are bypasedd by another relay operated again by simple one transistor timer.

Yeah you wanna Turbo you need more petroll one CL60 on a 1000VA tafo is not man enough for the job 2 do but get pretty hot
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Old 21st March 2012, 09:51 PM   #1083
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Quote:
Originally Posted by Bksabath View Post
http://www.diyaudio.com/forums/attac...etails-001.jpg

Heath spreaders
why did I not....?

Yeah You wanna Turbo you need intercoolers as well.

While you there and fix heath spreaders there is a bit of it that I like but may not be that plain to see.

Instead of using silly M3 (sorry for metric) screws with the danger of stripping the treads why not use captive bolts with the heads buried in the spreader
then clamp the mosfets with a bar and nut and washers on outside
This way one can use M4 or larger screws put much more pressure on the mosfets than a single screw would.

especialy if one use Kerafoll this give a much reduced heath Impedence
between mosfet body and the rest of the cooling system

If you can afford it get same cooper (or hunt around for scrap)
The radiated heat is lower than Aluminium (as cooper is mirror like) but the Thermal conductivity is mucho larger (twice ?)

Your sink will run much hotter but the mosfet will be cooler.

On soft start

If any one needs it I got momentary switch to operate a single transistor relay that puls inn the main Trafo trough 2 CL60 in series then the CL 60 are bypasedd by another relay operated again by simple one transistor timer.

Yeah you wanna Turbo you need more petroll one CL60 on a 1000VA tafo is not man enough for the job 2 do but get pretty hot
i have been thinking of your bar system. but be carefull!!! with M4 and nut, it's easy to tight it to much and crack the transistor case. use RIGTH amont of pressure. not as much as possible.
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Old 21st March 2012, 10:05 PM   #1084
labjr is offline labjr  United States
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Originally Posted by Bksabath View Post
http://www.diyaudio.com/forums/attac...etails-001.jpg

On soft start

If any one needs it I got momentary switch to operate a single transistor relay that puls inn the main Trafo trough 2 CL60 in series then the CL 60 are bypasedd by another relay operated again by simple one transistor timer.

Yeah you wanna Turbo you need more petroll one CL60 on a 1000VA tafo is not man enough for the job 2 do but get pretty hot
I haven't seen a DIY soft-start that does quite what I want it to. Need one with an on-board transformer, that will bypass a couple CL60's and will reset in case of power failure or brownout.
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Old 21st March 2012, 10:09 PM   #1085
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Originally Posted by AudioSan View Post
have to say i agree with that
15mm base might be a good one for class A with some depth.(and split sinks)
or some 10mm heatsprader on 10mm base maybe. this is a guess.
I guess the problem with a heat spreader is achieving good thermal coupling with the main heatsink.
How do you guys manage that?
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Old 21st March 2012, 10:10 PM   #1086
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then hypex is just in your street. and you got pushbutton/standby, on/standby LED and thermo breaker if you need it.
just pull out the resistors an solder 2 CL-60.
i have used that one for a load up to 1000VA 408.000uF and no problem.
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Old 21st March 2012, 10:11 PM   #1087
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Originally Posted by UKToecutter View Post
I guess the problem with a heat spreader is achieving good thermal coupling with the main heatsink.
How do you guys manage that?
yes it is. its a little pain

BTW: thats what i sayd in this thread a few weeks ogo.
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Old 21st March 2012, 10:13 PM   #1088
labjr is offline labjr  United States
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Originally Posted by UKToecutter View Post
I guess the problem with a heat spreader is achieving good thermal coupling with the main heatsink.
How do you guys manage that?
I imagine you spread some thermalcote on and bolt it together. I think the idea is that because heat spreads much farther quickly so the the thermal interface between the copper and aluminum is not quite as critical.

Last edited by labjr; 21st March 2012 at 10:16 PM.
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Old 21st March 2012, 10:16 PM   #1089
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Originally Posted by labjr View Post
I imagine you spread some thermalcote on and bolt it together.
Sure, I get that.
I'm just wondering how good the thermal coupling is.

I guess I'm trying to decide if I can move heat away from the MOSFETs quicker if they're directly on the heatsing rather than attached to a heatspreader which is then attached to the heatsink.
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Old 21st March 2012, 10:24 PM   #1090
labjr is offline labjr  United States
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I once thought of mounting the P type and N types devices on separate copper heat spreaders electrically isolated from the aluminum, so you can mount the outputs directly without any insulator reducing the case temperature even more.
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