View single post by Tramcar Trev
 Posted: Wed Feb 18th, 2015 03:50 am
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Tramcar Trev

Joined: Sat Mar 16th, 2013
Location: Gordon ACT, Australia
Posts: 399
Herb Kephart wrote:
The 80 - 90% efficiency means that 10 - 20% of the supplied current is dissipated as heat. Some of the ads you will notice offer ''heat sinks''. These keep the chip cooler and in marginal cases may eliminate thermal shut down.
You don't need to buy their aluminum finned extrusion, as it takes up considerable space. Any piece of thin aluminum will help, and of course the larger the better. A coat of flat black helps to shed the heat also. Be sure to put some heat conducting paste between the chip and the aluminum, what ever size you use, Beer and soda cans are a good source, and can be cut with scissors once the can is disassembled to a size dictated by the space available. Sand both sides of the metal (the inside has a clear coating) before painting with the flat black, and leave the section that will contact the chip bare, excepy for the heat compound.

Various size quantities, this is the smallest (and cheapest) at the present time on Ebay 

Strictly speaking this isn't necessary, but a cool chip is a happy chip.



We can have a really heated debate here Herb. While I agree that a cool chip is a happy chip I beg to differ on painting the heatsink. When I was involved with some students building an electric car the university did tests on the efficiency of heatsinks. Black anodising came out with the best performance followed by natural grit blasted aluminium then "mill finish" aluminium and last painted Aluminium, the single coat of paint acted as an insulator because at the interface between the paint and the heatsink there was a layer of air. Grit blasting increased the surface area by a staggering 30% over a finely machined surface... Generally the more surface area you can get the easier it is for the heatsink to dissipate the heat ergo slim people suffer the effects of heat more than portly built people...

There once was a man who said Damn!!
I perceive with regret that I am
A creature that moves
in predestinate groves
I'm not a Bus, I'm a tram
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