This is the second part about DIY portable size USB DAC TDA1541A including headphones amplifier. The first part can be find here
I successfully built a miniature, portable size USB DAC using a TDA1541A. I think it is the first TDA1541A DAC built in this small casing ever. But after all, it is still a desktop DAC headphones amplifier because it using the external power supply from the wall adaptor.
This design has a flaw. The heat from the regulator IC cannot dissipate efficiently. This is because no heatsink attached to them. This may cause the IC to fail and direct impact to the TDA1541A it self. So here is few solution I made to solve this heat issue.
My first trial is using a small heatsink that normally use in the Raspberry Pie mini PC. The heatsink is cheap and it including the thermal adhesive that can stick to the IC surface. This solution is works to reduce the heat by 30%, but it is still hot.
As you can see now, the board is full of heatsinks. I using the same heatsink attached to the TDA1541A IC. This TDA1541A get warm when operate and I think it is better to reduce the heat a little bit for more reliable performance.
Each op-amps also get heatsink on the top of them because they are get hot while it's operate. This is normal and not because an oscillating. Again, I better reduce the heat on them for more reliable performance.
When this DAC operate in open air, not inside the small casing, the heatsink do it's job to dissipate the regulator IC quite well. But not the same if I put it inside the casing. It is become very hot and still not a good solution for this heat issue.
So in the next morning I still evaluating the heat issue to this DAC performance and think how to solve this. Although no sign of degradation of sound quality and the distortion so far, but put the heatsink on the top of each IC is still not a reliable solution.
I think, I should rearrange the regulator IC as the final solution for this heat issue. This regulator should attach directly to the aluminum casing. This casing will works like a big heat-sink.
So I remove all the regulators and re-arrange the components.
I could say that this is not an easy work. Since all connection are point-to-point, then changing the layout could possibly change the whole connection layout.
But it is still fun to do.
I am using the new parts for the regulator IC. I using 4 regulator instead of 5 as on the initial design. This is because the USB PCM2706 doesn't require so much current and can be share from the 7805 that supply to +5 volt TDA1541A as well.
The idea for this new regulator IC placement would be up side down like this. The height must be measured well so the surface of the IC will attach firmly to the body of the case. I put the damper between the IC to the board using double side adhesive tape. This will to let the IC get well pressured from the board to the casing bellow it.
Besides this new regulator IC rearrangement, the mini jack connector for the headphones out also already delivered to me. So I install it on this board as well.
The redesign board is now finished.
Then I put this board inside the casing and make sure the surface of each regulator IC are attach firmly to the flat surface of the casing. The thermal paste also using on it.
Especially for the IC 7905, it should be isolated when attach to the casing. Using thermal isolator will works best to avoid the short circuit between IC to the casing.
After all IC are set to the bottom of the casing, I am make sure once again that they are sit well inside. They are quite happy I think:)
The last steps is only for the fitment of the casing.
This DAC is now finished. No heat issue anymore. All the heat from the components inside are dissipated very well. The casing is getting warm after several minute operate and this is very normal.
Disclaimer: Any statement and photos in this article are not allowed to copy or publish without written permission from the writer. Any injury or loss from following tips in this article is not under writer responsibility.
Good job!
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