power supply question

[Paul Perry]

At 02:53 PM 9/03/00 +0100, you wrote:
>Does it hurt if you connect an external power supply to a device, after it's
>own voltage regulator circuit?
.....I certainly wouldn't connect a supply to the output of another,
whether on a chip or wherever

>I does work, but does it hurt the internal power circuit?
.....I think you'd have to take it on a case-by-case basis.
Even the pretty indestructible 7805 doesn't like being backwards.
>
paul perry melbourne australia