> I just looked at the 7805 specs, and it tells me that the operating
> temp range is 0C to 70C (158 deg F).  So it sounds like I will
> have a problem eventually (assuming that the temp is not
> affecting anything else nearby).  BTW, max junction temp is
> 150C (302 deg F).

fortunately the 7805 has automatic shutdown on over temperature.  That will
protect the 7805 but your circuit will be out to lunch during a shutdown.

Is there no way to bolt a piece of sheet aluminum (copper would be even
better) between the 7805 and the pad and bend it up immediately at the sides
of the 7805?  That failing, string a few 1N4001 diodes in series at the
input of the regulator.  They will drop the voltage to the regulator a bit
and dissipate some of the power for it.  You can also use a power resistor
if you are very sure about the max current draw.  Either solution is ugly
though.

> I don't think I have room for a regular heatsink, but I can find
> room for a custom-made unit (bent piece of metal) about
> 1" x 1.75" (at least).  Could that be enough to solve the problem?
> I would probably use some aluminium for this, unless I can
> find a small copper sheet.

It's worth a try.  You may have use combinations of several methods.


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