Advangages of using new IRF240 in TO-204 package? - Page 2 - diyAudio
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Old 5th January 2006, 03:42 AM   #11
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I think part of the problem is that though steel does conduct heat well, it doesn't disipate it well (like to get hot, then stay hot).
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Old 5th January 2006, 04:44 AM   #12
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Steel is not a good conductor of heat compared to copper or aluminium
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Old 5th January 2006, 06:30 AM   #13
steenoe is offline steenoe  Denmark
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Quote:
Steel is not a good conductor of heat compared to copper or aluminium
That is correct, but doesnt have much to do with the case in point. The bigger TO-3 case has a larger area to transfer the heat to the heatsink as opposed to a TO247 with its much smaller steel-back

Steen.
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Old 5th January 2006, 11:23 AM   #14
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Isn't the TO-247 back (or TO-220 tab) usually plated copper?

[EDIT] Just scratched the back of an IRFP140 with a knife. Copper in deed. Perhaps that is the answer.
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Old 5th January 2006, 12:11 PM   #15
awpagan is offline awpagan  Australia
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Brien
copper backed, was that the TO-247 as well?

copper, probably best for heat transfer.

how about dye size between TO3 and TO-247?

Grey
"Be aware that metal cases are on their way out; the industry is moving to plastic cases."

Would have to be cheaper in assembling pcb's?

allan
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Old 5th January 2006, 12:31 PM   #16
steenoe is offline steenoe  Denmark
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Talking about cool looking output devices, take a look at these TO3's Looks pretty cool, right?
http://www.diyaudio.com/forums/showt...032#post654032

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Isn't the TO-247 back (or TO-220 tab) usually plated copper?
So is the TO3's underside.

Steen
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Old 5th January 2006, 01:51 PM   #17
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Quote:
copper backed, was that the TO-247 as well?
Yes. The IRFP140 is TO-247.
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Old 5th January 2006, 07:03 PM   #18
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That's an extreme case, and I don't reccommend it for everybody, but it's an option. Just something to think about.
Extreme?? Words of inspiration I see.

I got some NOS refrigerator compressors and evaporators, evap in front of a radiator, fans and well...thats another thread.

Grey, did I read correctly that you use irf644s for the outputs in your water cooled Aleph? If thats the case what changes (if any) did you make to the Aleph circuit to use these devices? Knowing pretty close to diddly squat about Fet intracacies, they look to be fine with serious active cooling. Aluminum L bar clamping the fets to the water block looks like all it will need.


John
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Old 5th January 2006, 10:11 PM   #19
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John,
I did a thread on this a few years back. If you rummage around a bit you can find it. There are other threads wherein people try to reinvent the wheel, but it was all covered way back when.
Keywords: water cooled
The upshot is that I used the heat exchanger from a defunct heat pump in conjunction with a water pump. I built the heat exchangers for the devices from copper pipe and copper bar. The details are in the thread.
I still use the system and it works great.
Changes to the circuitry? Yeah...I increased the bias by about 10%. If you pull the heat away from a TO-220, you can do amazing things. (And they're cheaper, too...)
Abandon hope, all ye who enter here...

Grey
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Old 5th January 2006, 10:24 PM   #20
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So is the TO3's underside.
So, does the steel cap act like a heat capacitor? Gotta be a reason it has a poorer thermal rating...
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