[sdiy] dissipator for power supply

[Linium]

On lundi 2 Août 2004 22:41, ASSI wrote:
> On Montag, 2. August 2004 21:00, Linium wrote:
> > i have choice between 3.9°C/W wich i know is quite good (and big and
> > $$) and another only 7.1°CW.
>
> Your setup is good for about 1A per rail with a voltage dropout of 3V,
> that makes 3W and that in turn means that the heat sink will be either
> at 11.7K or 21.3K above case temperature of the regulator. As long as
> the ambient temperature around it doesn't rise above 40°C there
> shouldn't be any problem with the smaller heatsink.
>
> How many modules are you planning to power and how much current they
> need? It sounds like you may be planning a bit too tightly... 7815
> regulators are available from 100mA to 3A current and 7915 up to 1.5A,
> so make sure you get the right ones (both 1A in your case). If you
> increase the power to 1.5A you need a 60VA transformer as well.
>
>
> Achim.

Achim, thks for the answer.

I have not yet an accurate idea about how many modules, 20 maybe. I intend tp 
mesure the consumption of each of them before putting them, anyway.

I have 1.5A rated 7815/7915 so i assume it is ok.

BTW, if 18v are rectified as 15v does it mean that the 1A current theorically 
available for the modules is downsized to 833 mA too?

Linium