Loudspeaker Components, Power Heatsinks
Aluminium Power Heatsinks.
SIMPLE RULES OF THUMB FOR POWER HEATSINKS.
1) The thermal efficiency increases as the square root of the heatsink width, hence a sink of 2 x width 2w only dumps heat at 1.4 x that of a single sink width w.
2) The heat loss is approximately proportional to the cooling fin width. So 80mm fins dump twice the heat of 40mm fins.
3) The heat loss is loosely exponential to heatsink extruded length, (height if you are looking at the pics). So if you know the °C/W, ie. loss figure at say 100mm cut length, then 200mm is approximately 0.6 of the 100mm value and 400mm is approximately 0.6 x 0.6 or 0.36. This may help calculate the efficiency of that old heatsink you were going to use.
4) Most manufacturer's loss figures are quoted at +60 above ambient temperature, so around 85°C.
5) Many choices of coloured heatsinks are possible but black anodised heatsinks give the best thermal loss.
6) Forced air flow can increase the conduction factor by roughly 3.
A Selection of high quality comb profile extruded aluminiun power heatsinks primarily used in the construction of Power Amplifiers. Machined and processed in the UK for QTA Systems. All items deburred along machined edges, etched and black anodised.
HEATSINKS - THE TECH BIT.
Used in many areas of electronics, heatsinks are often made from extruded aluminium alloy sections and are designed to transfer heat away from a hot source, thereby cooling the source. Pure aluminium is rather soft and so a number of other elements are often added to improve its characteristics and workability. Typically these are Silicon, Magnesium, Manganese, Iron and Chromium. Content ranges from (0.25 to 1.5)%. Different mixes provide for different characteristics. However, adding these impurities also reduces the thermal conductivity and so certain compromises have to be made.
For small to medium size heatsinks, aluminium is forced through dies, (like squeezee cheese or toothpaste), which forms the basic shape in lengths of (3 to 4)metres. This is then cut / machined to 'customer' lengths as required. The maximum width of a die is usually restricted to 300mm or so as above that it becomes more efficient / cost effective to fabricate the heatsink rather than to extrude it, a process whereby fins are welded to a base aluminium block. Heat sinks can be cooled by natural air convection or fan assisted which increases their efficiency. Many factors affect the efficiency.
The full study of heatsinks is complicated and extensive but the efficiency is quoted as a thermal resistance of °C/W, i.e. how many degrees the heatsink will rise in temperature per Watt of energy input. Figures vary from around 0.3°C/W to 50°C/W or more for the very small. These figures are used to calculate the temperature rise of components attached to the heatsink. How heat is "transferred" from a small hot component to a large cool one is complex and is known as spreading resistance, meaning that heat is not uniformly lost along the width of the heatsink.
In addition, the internal thermal resistance of attached semi-conductor devices has to be known, as must the thermal resistance losses between mounted component faces. The figures are then added. These values depend upon device case size, case insulating washers and / or thermal grease to aid heat conduction.
So, nuff said eh!
|Thermal rating:-||0.58 Deg C /W||0.84 Deg C/W||1.43 Deg C/W|
|Component mounting face:-||10mm thick||10mm thick|
|Order Code||Description||Price GBP|
|Power Heatsinks for DIY Amplifier Projects|
|HSINK01||A Heavy Duty Power heatsink for DIY Amplifiers etc. Good for 100W||24.80 / 1|
|HSINK02||A Smaller version of HSINK01 good for 50W||9.86 / 1|
|HSINK03||A PCB Mounted Heatsink for use with T0220, T0218 and T0247 Packages||14.73 / 1|
See BUY IT for further information.
All Prices include VAT @ 20%.