Scott,
Sorry to burst your bubble, but I was talking about no forced air. Forced air is so much more efficient it will drop radiation to insignificant.
I am sure you remember the first high power solid state amplifiers like the Crown DC 300. 155 watts per channel all passive cooling. 3 rack units high. Today in two rack units with still class AB you can get 2000 watts per channel. Better semiconductors, heat sink design and fans. Do note the fan cooled heatsinks are not anodized black!
There just ain't much to argue about. No fan paint it black, fan... just turn up the speed.
Sorry to burst your bubble, but I was talking about no forced air. Forced air is so much more efficient it will drop radiation to insignificant.
I am sure you remember the first high power solid state amplifiers like the Crown DC 300. 155 watts per channel all passive cooling. 3 rack units high. Today in two rack units with still class AB you can get 2000 watts per channel. Better semiconductors, heat sink design and fans. Do note the fan cooled heatsinks are not anodized black!
There just ain't much to argue about. No fan paint it black, fan... just turn up the speed.
What the primary difference in how a radiator cools water (as in an automobile) and the fins of a transistor heat 'sink'?
Thx-RNMarsh
Thx-RNMarsh
The difference is that the DC300 was in a shallow chassis, and that 2000W AB amp will be deeper than it is wide.
Why are consumer automotive radiators (water, oil etc) painted black but radiators for racing engines are not painted/anodized?
[its not to hide them from bugs]
Thx-RNMarsh
[its not to hide them from bugs]
Thx-RNMarsh
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Hardly a guess, I've welded both, new and repair jobs, made my own intercoolers.
(+ hand forged classic fireplace hearths for pocket money during highschool days, twist and twirl, including the tricks to turn them nice and black)
(+ hand forged classic fireplace hearths for pocket money during highschool days, twist and twirl, including the tricks to turn them nice and black)
Aluminum is lighter, but more fragile.
Fancier cars have aluminum radiators, but cheapos still do thin steel.
Back in the old days copper, easy to repair, but expensive nowadays.
Intercoolers for boats are copper.
Fancier cars have aluminum radiators, but cheapos still do thin steel.
Back in the old days copper, easy to repair, but expensive nowadays.
Intercoolers for boats are copper.
A war story
Noting the remark about the over torquing of TO-220 cases that use a bolt through the tab hole reminded me of a debacle with a subwoofer developed for Dell. It was one of a few experiences which taught me to monitor the progress of a product after development and testing, after a handoff to manufacturing.
Although there is no net airflow, the scrubbing action of directing the port air over a heatsink surface can be quite helpful in cooling. In this case the power IC was a Toshiba part in a large rectangular package, which had slots in the ends of the long dimension. The mounting surface was aluminum and the thickness was determined to be adequate for both heat spreading and mechanical flatness. Since in the vast majority of cases the low-frequency content of the music followed the familiar spectral distribution, the scrubbing action from the internal end of the tuned port in proximity to the surface worked well and allowed use of a relatively small amount of material, reducing costs. As well the power IC was supposedly thermally protected.
Testing with a variety of source materials indicated the device temperature was well within recommended limits. Things were handed off and production began.
However, I was not informed of a last-minute change instigated by the fabricator of the aluminum piece. They were complaining that the material was too thick to easily bend, and the person in contact simply told them to make it thinner. Bad bad idea. Besides lacking any thorough testing of the diminished conductivity, the material was now susceptible to bowing which drastically reduced the effective contact area between the device surface and the aluminum.
Most customers didn't push these systems all that hard. But the few who did exercised the protection circuitry, and it turned out that, as well, this wasn't very good, and a few cycles would induce catastrophic failure.
The interesting thing about this particular three-piece system was the amount of "invention on the critical path", which is usually cited as a no-no by quality assurance folk. But in my experience, the significant failures are rarely associated with such invention, and are almost always very dumb-$hit and sloppy blunders like this example. The one other problem this system had initially was from flux contamination which led to a d.c. shift in the gate input on a uC that pushed the operating point away from sufficient gain to start the local clock. The package geometry was the smallest easily obtainable and was needed to get everything to fit on the board, which lived in one of the satellites. Hindsight showed that some guarding around the one pin biased at ~1/2 Vdd might have helped. There was little point to insisting that the process needed to be better, given the politics (at Harman things were very dominated by a rather anti-engineering animus, with manufacturing and quality assurance perceived as the holy grail).
Noting the remark about the over torquing of TO-220 cases that use a bolt through the tab hole reminded me of a debacle with a subwoofer developed for Dell. It was one of a few experiences which taught me to monitor the progress of a product after development and testing, after a handoff to manufacturing.
Although there is no net airflow, the scrubbing action of directing the port air over a heatsink surface can be quite helpful in cooling. In this case the power IC was a Toshiba part in a large rectangular package, which had slots in the ends of the long dimension. The mounting surface was aluminum and the thickness was determined to be adequate for both heat spreading and mechanical flatness. Since in the vast majority of cases the low-frequency content of the music followed the familiar spectral distribution, the scrubbing action from the internal end of the tuned port in proximity to the surface worked well and allowed use of a relatively small amount of material, reducing costs. As well the power IC was supposedly thermally protected.
Testing with a variety of source materials indicated the device temperature was well within recommended limits. Things were handed off and production began.
However, I was not informed of a last-minute change instigated by the fabricator of the aluminum piece. They were complaining that the material was too thick to easily bend, and the person in contact simply told them to make it thinner. Bad bad idea. Besides lacking any thorough testing of the diminished conductivity, the material was now susceptible to bowing which drastically reduced the effective contact area between the device surface and the aluminum.
Most customers didn't push these systems all that hard. But the few who did exercised the protection circuitry, and it turned out that, as well, this wasn't very good, and a few cycles would induce catastrophic failure.
The interesting thing about this particular three-piece system was the amount of "invention on the critical path", which is usually cited as a no-no by quality assurance folk. But in my experience, the significant failures are rarely associated with such invention, and are almost always very dumb-$hit and sloppy blunders like this example. The one other problem this system had initially was from flux contamination which led to a d.c. shift in the gate input on a uC that pushed the operating point away from sufficient gain to start the local clock. The package geometry was the smallest easily obtainable and was needed to get everything to fit on the board, which lived in one of the satellites. Hindsight showed that some guarding around the one pin biased at ~1/2 Vdd might have helped. There was little point to insisting that the process needed to be better, given the politics (at Harman things were very dominated by a rather anti-engineering animus, with manufacturing and quality assurance perceived as the holy grail).
Someone likely nicked my brainstem.
Regular aluminum car radiators here are a mix, center is all aluminum and blank alloy, ends are painted and non-aluminum, or plastic nowadays.
(but hey, what do and should I know about the US market)
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I gave the parameters to the question and it wasnt about anyones country, make or model. it was just about color. If you like... why are the race cars radiators not black?
It gets at the heart of the heat sink fins issue being discussed.
Thx-RNMarsh
Ed the feeling is mutual, it's known as the Stefan-Boltzman equation. Just plug-in the numbers (did you read my answer?) 1W per square meter at best radiative cooling at 100C heat-sink temperature (that's HOT but T^4 is a killer). Why do you think the moving air works? Hint, the air is not heated (much) by radiation absorption. Like all things audiophile this discusstion has insufficient separation of effects in order to consider it a scientific observation.
BTW the heat exchangers in HVAC that I have seen are never black.
EDIT - read some of the web disscussions of "should heat sinks be black" they are really funny, the entire gamut of possibilities "proved" by homebrew experiments.
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Jacco, speaking of heat I gave my knees a capsaicin rub down this morning and wore shorts for the first time this spring. An absent minded hand to the eyes later in the morning and you can guess...
Another thought experiment
I'm sitting in a room with no remarable sources of heat and everything at an equilibrium. I have a very polished aluminum plate on the table with half painted flat black. My IR irradiance thermometer says both halfs are at the same temperature, what's going on?
I'm sitting in a room with no remarable sources of heat and everything at an equilibrium. I have a very polished aluminum plate on the table with half painted flat black. My IR irradiance thermometer says both halfs are at the same temperature, what's going on?
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