I wonder if its possible and enough to use just a raw piece of aluminum 4mm thickness vertically oriented that is going to be something like 8 cm wide and 60 cm long for a heatsink for a typical 60W class AB amplifier with a couple of 1943-5200
Transistors are going to be fitted in the down side and the all construction will be standing up so i expect the heat to distribute vertically starting from down and going up
any comments ?
Transistors are going to be fitted in the down side and the all construction will be standing up so i expect the heat to distribute vertically starting from down and going up
any comments ?
Is this a stereo amp or mono? If stereo are both channels on the same sink? With only 4mm of thickness conduction may be a problem unless you plan to spread the transistors out a bit as Alan0354 stated. This will be especially true if two 60W channels are on the same bar. An L-Channel like the dynaco one would be better as it would put some of the heat from the L channel into the lower panel it is connected to.
Well no ... this part will be for just one ch only and even though the 60X8 cm will be the heatsink this will be also housed in aluminum brackets lengthwise side to side mounted with screws so actually some of the heat will dissipate from there also.
I will be able to produce a sample next week and some pics
Thanks for your help so far
I will be able to produce a sample next week and some pics
Thanks for your help so far
[(V+abs(V-)]^2)/(2*pi*pi*RL)
If you're designing for 8R Pdmax is 31W requiring a heatsink of 2.8 C/W, for 4R, it's 62W requiring a heatsink of 0.96 C/W
If you were to use aluminum flashing, you'd need ~40 square inches in free air to attain 2.8 C/W
TI took the "Overture Design Guide" (from Nat Semi) off their website. It's an Excel file which I am having difficulty attaching. PM me if interested.
You mean like this?
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I don't know the purpose of your amp and your budget. But I would buy the right heatsink. I just bought and received two of this: 2 Pieces Dense Teeth Fin Heat Sink for Power Amplifier Heatsink 300 69 36mm | eBay
Total for $61 something. I just received them. I am sure they are going take 60W each easily. I am using these two to nail onto the wood prototype platform to build my amp. Debug and tune before I even try to drill into the expensive chassis.
60cm long piece is not going to make a day to day liveable amp!!! You have to worry about how it fit at home, even on the bench!!! Don't try to save a penny and loss a dollar.
Attached is my heatsink with TO-264 MJL1302 to serve as size reference.
Total for $61 something. I just received them. I am sure they are going take 60W each easily. I am using these two to nail onto the wood prototype platform to build my amp. Debug and tune before I even try to drill into the expensive chassis.
60cm long piece is not going to make a day to day liveable amp!!! You have to worry about how it fit at home, even on the bench!!! Don't try to save a penny and loss a dollar.
Attached is my heatsink with TO-264 MJL1302 to serve as size reference.
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C/W of alum. 'L' stock
I actually have a couple Dyna 120's and that got me to thinking about what I could do with aluminum 'L' stock for a heat sink. I know fins are better, but I have a LOT of aluminium 1/8" x 2" x 2" 'L' stock. Can anyone tell me how to calculate the C/W of a given length? I know it is not a linear function, but is there a formula for just an aluminium bar? (I'll take the dissipation onto base as bonus.)
There are ways to guesstimate it, but the real test is bolting on the device with isolation pad and thermal grease,
burning power, and measuring the device case temperature (on the tab).
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That is what I was looking for. I did not think it was a linear function as shown, but it sure makes life easier. It doesn't take into consideration thickness, but maybe that works more like a capacitance to sink heat until unit reaches steady state and then surface area is all that matters. Sort of makes empiric sense.
Thanks
The graphs are more clear in this reference. Shows the asymptotic behavior clearly.
How to Select a Suitable Heat Sink
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