> Since you mention cascading, I have this situation frequently and instead
of
adding a (relatively) large heatsink, I use 2 regulators in "series" -- a
7810 to drop the 13.8V to 10V, then send that to the 7805 to drop it to 5V.
Cost is another 35c or so for the 7810 regulator.
>

A word of warning - while there may be some advantage in doing this, there
is no free lunch.

This practice reduces the dissipation in any one component but the overall
dissipation is the same.
If the regulators are on the same heatsink, the heatsink has to dissipate as
much energy as it would have had to if there had only been one regulator.


        Russell McMahon

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