[sdiy] -48V dc/dc converters

[John L Marshall]

Hints.
A single wire on the ground.
Electrolysis.

Take care,
John


----- Original Message -----
From: Paul Schreiber <synth1 at airmail.net>
To: <synth-diy at dropmix.xs4all.nl>; Ken Stone <sasami at hotkey.net.au>
Sent: Thursday, April 18, 2002 6:13 AM
Subject: Re: [sdiy] -48V dc/dc converters


> ->
> > does anyone know anything about -48V dc/dc converters? I have several
here
>
> -48V is the "industry standard" voltage for telephone central offices. All
rack-based electronic
> in the telephone industry runs off of a -48V feed.
>
> For 100 brownie points: why is it a "negative" voltage instead of a
positive one? The 48V comes
> from 1920's wet-cell battery technology.
>
> Paul S.
> was designing phone stuff in a previous life
>
>