Due to the number of variables involved (shape of case, orientation,
vent holes, etc.), I think it's a whole lot easier to just try it and
measure the results. I've done this a lot with light dimmers. I put a
thermocouple on the thing I think is dissipating the most heat inside the
box, then run the device until the temperature stabalizes. Calculate the
temperature rise. Look at ratings on components and compare that to max
ambient plus the measured temperature rise.

Harold



On Tue, 8 Jan 2002 15:19:37 -0600 Lawrence Lile <llile@TOASTMASTER.COM>
writes:
> Does anybody have a good guideline for using the project case as a
> heat
> sink?  It may be either a flat piece of aluminum or flat piece of
> steel.
> You can find manufacturer's data on heat sinks easily, but I haven't
> turned
> up anything on a flat heat sink either on the web or in Art of
> Electronics.
>
> Seems like there was a rule of thumb - so many square inches of
> surface area
> (aluminum)  would give so many degrees C per watt.  This is the kind
> of
> thing I used to keep an old ARRL handbook around for, but I've long
> since
> lost track of it.  A net search turned up long treatises on using
> manufacturer's heat sink data ( which is trivial) but no practical
> rules of
> thumb for sizing a simple flat aluminum plate heat sink.
>
> I could measure it (I've done this) but this is just a one-off piece
> of test
> equipment, seems a bit much.
>
>
> -- Lawrence
>
> --
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>

FCC Rules Online at http://hallikainen.com/FccRules
Lighting control for theatre and television at http://www.dovesystems.com

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