"zaa"
[email protected] wrote in message
Arfa Daily Wrote:
"James Sweet"
[email protected] wrote in message
zaa wrote:
I got three cameras i bought for surveillance and I got a power box
(12vdc 4 output 2 amp). I got 100ft cables for each camera with two
lines joined to getther (video and power) In order to connect the
power
to the power box, i had to cut open the wire. It wasnt red and black
as
i hoped, so I can tell which is positive and negative. Instead the
two
wires consisted of an inner wire in the middle with insulation and
naked wire around it on the outside, the entire thing has an outer
insulation coating.I just need to know which is positive I think the
sales guy said the middle wire withthe coating is neutral and the
outer
is negative. I just want to be sure. and any tips on the proper way
to
attach wire to + and - screws on the power box? since they are very
thin wires (carry 12 v) sorry for the essay
That's coax, generally the middle wire is signal and the outer shield
is
ground. You need to use propper connectors to splice coax or your
picture
will suffer, though with security cameras you can probably cheat and
just
solder splice the wires and tape the joints and not notice.
If it's two joined together, then it's probably " figure 8 " audio
screened
cable. In general, the centre conductor will have been designated "
"
and
the outer shield, ground ( " - " ) but this is only a convention, and
not
set in stone. If the other cable is the ' video out ', then with 99%
certainty, the screen of that one, will be ground. If you the
measure
with
an ohm-meter between the two shields, and they read shorted together,
then
you can be pretty much certain that the shield of the power cable i
"
- "
and the centre, " + ".
To join to the screw terminals, you can un-plait the screen, an
twist
it
back into a pigtail, slip a bit of sleeving over it, and treat it a
a
normal wire, or solder and sleeve a pair of thicker wires to the thin
ones
or, best solution, solder the inner, and pigtailed screen, to solder
tags,
which can then be firmly screwed to the power unit.
Arfa
just so I understand you are describing the power cable right (it
two
cables joined together, split up on the ends, one has bnc connectio
on
both ends goes from camera to the DVR the other is the power which is
what I am trying to connect to the power box. )
When you said un plait i guess youmeant taking off the coating, I was
planning to twist the wires (i didnt mention that they are both like
vermicelli or very thin strands of hair and not one piece of coppe
and
also the outer wire is about 3 times thicker than the middl
insulated
one)
and the solder tags I guess would have to be small enough to fit i
the
power box (not a lot of space and would need 4 tags)?
--
zaa
I think that we must be misunderstanding exactly what your cable look
like.
The section with the BNC on each end, must be some kind o
concentrically
constructed cable - either coax or some other kind of screened cable
but
that's neither here nor there.
I, and I think other posters, were assuming that the second ( power
cable
was also some kind of concentric cable, with a central insulate
conductor,
surrounded by an uninsulated braided shield, surrounded by an oute
plastic
jacket. That's what it sounded like you were describing. If this wer
the
case, then by " un-plaiting ", I was referring to first exposing th
braid,
by removing the outer jacket for a short distance, and then ' unpickin
'
the exposed braid until its just a bunch of individual strand
surrounding
the inner insulated conductor, then pulling all those strands together
and
off to one side, so that they can be twisted together to form a ' wir
'.
Does this sound like what you have as a power cable ? How is this
cable
terminated at the camera end ?
Arfa
