Re: Powering an In-wall Amp

[ddl@danlan.*com (Dan Lanciani)]

In article <50cb70803eda48c81ca3ed807842@xxxxxxxxxxxxxxxxxxxxxx>, bph@xxxxxxxxxxxxx (Byron Hynes) writes:

|So, realistically, could I run 12V DC (or so) through my 2500 sq ft house
|to get rid of some wall warts? (Possibly driving it off a solar panel/battery,
|for that matter).

The problem I usually encounter with such schemes is that many of the
little gadgets that are powered by wall warts depend on those wall warts
for isolation.  That is, the negative power supply input may well not
be the same as the negative/ground connection of any i/o, audio in/out,
etc. of the device.  Some devices that don't otherwise depend on the
isolation try to help you by putting a bridge rectifier at the supply
input.  That means that the internal ground/common is going to be one
diode drop away from the power input negative.

If you power two or more devices that need isolation from a common supply
and if those devices are directly or indirectly interconnected then you
can get some pretty strange behavior or even damage.  If the devices have
no external connections or if you can be sure that the connections are either
isolated or referenced to the same ground then you should be ok.  In general,
I find it sufficiently difficult to be sure of this that I don't replace
multiple wall warts with a single supply even when they are all on the same
power strip...

				Dan Lanciani
				ddl@danlan.*com