Re: DC Supply Question

Thank you all for the posts!

The camera is a 2.4GHz unit which is actually being used as a baby monitor
so no separate coax feedline. (I am trying to avoid using AC power
extension cables and power strips to make this installation less obtrusive).

The power cube is rated as 115VAC / 60Hz input and 1A @ 12VDC output with
positive tip / negative sleeve. So I guess since this cube has a step down
transformer, the output would be floating due to the magnetic coupling
effect of the transformer.

So what I am getting from the various posts, is that, it although there are
no other ways current can find another route to the camera b/c there is no
video feedline, it can't hurt to interrupt the + side nonetheless as good
practice should other factors be involved.



You know whats also interesting, when I decided to relocate the camera, I
took the existing stock power cube and spliced in additional cabling to
accommodate the added length requirement and measured the open circuit
voltage on this cube at the newly added barrel plug termination on this
extension and read 18VDC on both a portable DMM that has 10MOhm's input
resistance as well as my Fluke 8840/AF which has 10GOhm input resistance.
I then looked through my junk box and found another similarly rated power
cube and it too read 18VDC ? What's going on here ... I would expect the
regulation circuit in these cubes to present 12VDC at the output from open
circuit right through to a 1A load.



"John Miles" <jmiles@xxxxxxxxxxxxxxxxxxxxxxxxxx> wrote in message
news:MPG.1d1f25d697df09059896d1@xxxxxxxxxxxxxxxxxxxxxxxxxxxx
> In article <Xns967A5B3A068C4831041831041@xxxxxxxxxxx>, me@xxxxxxxxxxx
> says...
> > In response to what John Miles <jmiles@xxxxxxxxxxxxxxxxxxxxxxxxxx>
posted
> > in news:MPG.1d1e84e5f326f18d9896d0@xxxxxxxxxxxxxxxxxxxxxxxxx:
> >
> > > You want to break the positive side, not the negative. Otherwise,
> > > power-supply current may find another route through traditional
> > > "ground" conductors, like the outer shield of your video cable, or the
> > > camera's mounting bracket.
> >
> > No it will not. Power supply outputs of this kind are floating - no
> > 'earth' connection.
> >
> >
>
> I don't know that from the poster's description, though, and neither do
> you.
>
> Break the positive side.
>
> -- jm
>
> ------------------------------------------------------
> http://www.qsl.net/ke5fx
> Note: My E-mail address has been altered to avoid spam
> ------------------------------------------------------


.

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