Re: Powering an In-wall Amp

[Byron Hynes <bph@xxxxxxxxxxxxx>]

Thanks.

> 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