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Re: Dual Class-A Line and Headphone Output Board Documents

Posted: Tue Mar 15, 2016 9:06 pm
by Gold
I'll see if it works tomorrow.

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Re: Dual Class-A Line and Headphone Output Board Documents

Posted: Wed Mar 16, 2016 2:13 pm
by Gold
Fail! Oh well. The screws don't transfer much heat. Almost none. Time for plan b. I guess I need a plan B.

Re: Dual Class-A Line and Headphone Output Board Documents

Posted: Wed Mar 16, 2016 7:53 pm
by JR.
Gold wrote:Fail! Oh well. The screws don't transfer much heat. Almost none. Time for plan b. I guess I need a plan B.
Steel is not a great thermal conductor but should still move a bunch of heat out of the box... (bet it will burn your finger).

2 more screws/studs would double the heat transfer.

Making them shorter could proportionately move more heat, if they are the limitation.

Think of heat as current. Heat flowing through a thermal resistance will cause a temperature drop, shorter screws will drop less heat making the external heat sink hotter to dissipate more power.

I suspect it is helping more than you think, I wouldn't bail on the plan just yet.

JR

Re: Dual Class-A Line and Headphone Output Board Documents

Posted: Wed Mar 16, 2016 8:41 pm
by Gold
I could put some thermal grease in the tapped holes, add a washer or two with thermal grease to increase the mating area. It's not too bad especially if I don't leave it on all day. I was expecting more heat transfer though. I was trying to picture is as plumbing or current.

Re: Dual Class-A Line and Headphone Output Board Documents

Posted: Thu Mar 17, 2016 9:47 am
by JR.
Gold wrote:I could put some thermal grease in the tapped holes, add a washer or two with thermal grease to increase the mating area. It's not too bad especially if I don't leave it on all day. I was expecting more heat transfer though. I was trying to picture is as plumbing or current.
Thermal grease mainly helps when mating two flat surfaces.. the grease fills in air pockets that are insulators. A screw thread should make a decent metal to metal contact.

I think i suggested earlier some hollow aluminum spacers, or even threaded aluminum stand-offs might help. Image
http://www.mcmaster.com/#threaded-standoffs/=11kudfj

JR

Re: Dual Class-A Line and Headphone Output Board Documents

Posted: Thu Mar 17, 2016 3:37 pm
by Gold
I thought thermal grease would fill the air gaps in the thread mating. I'd also use it with washers to improve contact. I only have 4/40 standoffs. I can't imagine using #10 or larger standoffs for very much. I have both copper and aluminum 1/4" round stock. I could tap some stock. Maybe four 1/4" copper or aluminum rods would still have enough strength to use the outside bar stock as a handle and mounting bracket.

Of course I can always just open the top if it gets too hot.

Re: Dual Class-A Line and Headphone Output Board Documents

Posted: Thu Mar 17, 2016 4:17 pm
by JR.
I didn't realize that was only #4 hardware.. looks bigger in picture.

for thermal conductivity steel is like 43... whatever units, aluminum is 205 units, and copper is 401 unit... so copper is almost 10x as heat conductive as steel...

Copper isn't as strong but would kick ass for heat transfer. Some 1/4" round stock could work... again shorter is better. I've never tried to tap threads in copper, it's soft and ductile.. good luck. Even aluminum would spank the steel like 5x better.

JR

PS: Copper is better than gold (only 300) :lol:

Re: Dual Class-A Line and Headphone Output Board Documents

Posted: Thu Mar 17, 2016 4:22 pm
by Gold
The screws are #10. I was saying the only standoffs I have are 4-40. The holes are #29 tapped for a #10 screw so too big for a 4-40. #29 is a little less than 3/16".

Re: Dual Class-A Line and Headphone Output Board Documents

Posted: Thu Mar 17, 2016 4:36 pm
by JR.
The link I posted earlier shows #10 threaded aluminum standoffs for tens of cents....

5x better than steel... cheap.

JR

Re: Dual Class-A Line and Headphone Output Board Documents

Posted: Thu Mar 17, 2016 4:59 pm
by Gold
I have thousands of dollars worth of hardware and metal stock. I can figure it out with what I have