Will try the heatsink, but it would be nice to be able to calculate (with
reasonable ease :-) how much heat dissipation to expect per sq in of
heatsink.  To make matters worse, this is in a friend's car (out of town),
so I'll probably have to have him ship me the unit.

I was thinking similarly about dropping the voltage a bit before letting
the regulator have it, but I thought of 2 regulators -- first drop to 9V
or 8V, then the 7805.

Only other thought is to move the power-supply remotely.


> 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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