SA2015 V-MOSFET Builders

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thimios

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Joined 2009
My plan is for two holes drilling in the heatspreader ,one 5mm hole for the vbe transistor and one 3,5mm for the led.
Is this a good solution?
 

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astx

astx

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Joined 2011
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Of course a possibility: 2-3 mm deep hole should be enough. Fill it with a little bit thermal grease. Or just add a squishy spacer between pcb and BC550C as AndrewT has done.
The red LED need not to be in direct thermal contact with the heatsink - only between pcb and heatspreader.

BR, Toni
 
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thimios

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Joined 2009
astx said:
I'm sure it will do its coooooling! ;)
Click to expand...
The heat spreader drilled using 6mm drill for the center and 10mm for the top.
The heatsink drilled using 3.5mm then 4mm and tapped with a 5mm, sharpened to the lower end,tapping tool.
Screws are 5x12mm inox .
All parts cleaned using dish washer liquid for tapping fluid removing.
After drying a plenty of thermal paste applied
Aluminum was pressed as in the picture to reduce the gaps to the minimum.
Finally the screws tightened.
 
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Project16

Project16

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Joined 2012
Hello Thimios

I see that you have positioned the plate with the holes as I told you. With this layout you will not have to drill the bottom of the case, just for the feet.
Congratulations for your work and I think you will really have no problem with heat dissipation. :D

Regard's
 

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T

thimios

Member
Joined 2009
Project16 said:
Hello astx

This amplifier interests me (I do not know yet which version) but can this be suitable with only 2 pairs of hexfets by lowering the supply voltage?

Thank you :)

PS: Thimios, I'm sorry to ask my question on your thread.:eek:
Click to expand...
Never mind,i think yes and yes.:)
Toni has designed many different versions.
You must wait for his answer.;)
 
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astx

astx

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Joined 2011
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thimios said:
Analytical thermal condition.
Power supply=+/-42V
Idle current=150mA/pair
Mixed operating cycle, high volume, low volume,no out.
Maybe i need better quality transistor insulators?
Click to expand...

What have you used as isolators? I've used keratherm red ... (conrad)
Test it with high continuous output power for several minutes to see how the temperature rises. Stop tests if going too fast above 60 degrees.
But looks good so far. (Bias idle current produces 38W dissipation! You have more as one class A watts for listening). :)
The MCU board has connections for 3 NTC resistors. If you are finishing the assembling of your amplifier add one NTC at each heatsink and one in the internal middle of your amplifier.

BR, Toni
 
T

thimios

Member
Joined 2009
astx said:
What have you used as isolators? I've used keratherm red ... (conrad)
Test it with high continuous output power for several minutes to see how the temperature rises. Stop tests if going too fast above 60 degrees.
But looks good so far. (Bias idle current produces 38W dissipation! You have more as one class A watts for listening). :)
The MCU board has connections for 3 NTC resistors. If you are finishing the assembling of your amplifier add one NTC at each heatsink and one in the internal middle of your amplifier.

BR, Toni
Click to expand...
Silicone Rubber gray color together with thermal paste.
Unfortunately keratherm aren't available here.
Test it with high continuous output power for several minutes to see how the temperature rises. Stop tests if going too fast above 60 degrees.

60°c, where i must take this measurement?on the main heatsink or direct on transistors body?
 
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