Carl Denk wrote:

> I'm assuming I need a heat sink, probably prefer a heat sink on the 
> board, but could screw the grounded tab of the 7805 directly to the 
> aluminum box.

The reason why you got the advice (a couple times) to use the box as a heat
sink is that any in-the-box heat sink could only improve the heat transfer
from the chip to the box -- which you can improve much easier by mounting
the chip directly to the box. 

Gerhard

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