Coaxial cable to video sensor: sending DC 12V?

18 May 2006 1:53 AM

raveneye

I recently bought a video bullet camera manufactured by ISCO that is
powered by a coaxial cable (RG 58 type A) that carries both the power
through the unit and the video signal simultaneously. It comes with a
power supply that allows you to plug the unit into an AC outlet: you
plug the coaxial cable (BNC connector) into the power supply, plug the
power supply into the wall, and the video out signal comes from a BNC
outlet in the same power supply. The video camera itself requires 12V
DC, and the power supply takes the AC and converts it to DC for the
camera.

My question: can I run this camera directly from a 12V DC battery (car
battery)? I have no idea how a coaxial cable like this can carry both
power and video signal simultaneously. For example, is there an
adapter that I can plug the cable into that separates the power from
the video? Then the power portion of the cable I could connect to the
battery contacts, and the video portion I could then connect to a
monitor.

Any help appreciated!

18 May 2006 2:25 AM

Pooh Bear

raveneye wrote:

Show quoteHide quote

> I recently bought a video bullet camera manufactured by ISCO that is
> powered by a coaxial cable (RG 58 type A) that carries both the power
> through the unit and the video signal simultaneously. It comes with a
> power supply that allows you to plug the unit into an AC outlet: you
> plug the coaxial cable (BNC connector) into the power supply, plug the
> power supply into the wall, and the video out signal comes from a BNC
> outlet in the same power supply. The video camera itself requires 12V
> DC, and the power supply takes the AC and converts it to DC for the
> camera.
>
> My question: can I run this camera directly from a 12V DC battery (car
> battery)? I have no idea how a coaxial cable like this can carry both
> power and video signal simultaneously. For example, is there an
> adapter that I can plug the cable into that separates the power from
> the video? Then the power portion of the cable I could connect to the
> battery contacts, and the video portion I could then connect to a
> monitor.

I'm sure it can be done. Have you asked the manufacturer if they supply
something suitable ? I'd have thought it was a likely enough requirement for
them to have considered this.

Graham

18 May 2006 3:08 AM

sinoline

Rolf wrote:
The RF is isolated from the 12v DCon the center conductor with
capasitors. The RF pass through the capasitors the DC does not.

18 May 2006 4:35 AM

Pooh Bear

sinol***@charter.net wrote:

> Rolf wrote:
> The RF is isolated from the 12v DCon the center conductor with
> capasitors. The RF pass through the capasitors the DC does not.

You'll also need to 'isolate' the DC adaptor output with an inductor too ( which
passes DC but blocks the video signal ) .

Graham

18 May 2006 1:02 PM

raveneye

Thanks for your replies.

I've tried contacting the manufacturer (in Taiwan) by email and phone,
but have not received any response, hence the post to this group. It
seems like a simple problem, all I would need is some kind of adapter
that separates out the video from the DC. I don't have the experience
to build one myself, unless there were some detailed step by step
instructions published somewhere.

18 May 2006 1:21 PM

SamSez

"raveneye" <junkmails***@bellsouth.net> wrote in
news:1147957351.145739.278030@j73g2000cwa.googlegroups.com:

> Thanks for your replies.
>
> I've tried contacting the manufacturer (in Taiwan) by email and phone,
> but have not received any response, hence the post to this group. It
> seems like a simple problem, all I would need is some kind of adapter
> that separates out the video from the DC. I don't have the experience
> to build one myself, unless there were some detailed step by step
> instructions published somewhere.
>
>

A google for "phantom camera power coax" will give you all the leads you
need.

18 May 2006 1:56 PM

Jim Thompson

On Thu, 18 May 2006 13:21:09 GMT, SamSez <samthe***@verizon.net>
wrote:

Show quoteHide quote

>"raveneye" <junkmails***@bellsouth.net> wrote in
>news:1147957351.145739.278030@j73g2000cwa.googlegroups.com:
>
>> Thanks for your replies.
>>
>> I've tried contacting the manufacturer (in Taiwan) by email and phone,
>> but have not received any response, hence the post to this group. It
>> seems like a simple problem, all I would need is some kind of adapter
>> that separates out the video from the DC. I don't have the experience
>> to build one myself, unless there were some detailed step by step
>> instructions published somewhere.
>>
>>
>
>A google for "phantom camera power coax" will give you all the leads you
>need.

Close to 40 years ago there was an over-the-air UHF TV channel that I
couldn't receive because I was (literally) in the shadow of a
mountain.

But 150' west in my back yard there was ample signal.

So I ran 18-24V down the coax to varactor adjust a UHF tuner (after
level-shifting), then a 12V linear regulator to run the tuner itself,
and piped back IF on the coax.

You just need to think through the filters to keep everything
separated.

...Jim Thompson

--

I love to cook with wine. Sometimes I even put it in the food.

18 May 2006 2:36 PM

Tzortzakakis Dimitrios

Show quote Hide quote

? "Jim Thompson" <To-Email-Use-The-Envelope-I***@My-Web-Site.com> ?????? ???
?????? news:huuo625p9kesvfdu1ubgdrtppsrq8o4uu1@4ax.com...
> On Thu, 18 May 2006 13:21:09 GMT, SamSez <samthe***@verizon.net>
> wrote:
>
> >"raveneye" <junkmails***@bellsouth.net> wrote in
> >news:1147957351.145739.278030@j73g2000cwa.googlegroups.com:
> >
> >> Thanks for your replies.
> >>
> >> I've tried contacting the manufacturer (in Taiwan) by email and phone,
> >> but have not received any response, hence the post to this group. It
> >> seems like a simple problem, all I would need is some kind of adapter
> >> that separates out the video from the DC. I don't have the experience
> >> to build one myself, unless there were some detailed step by step
> >> instructions published somewhere.
> >>
> >>
> >
> >A google for "phantom camera power coax" will give you all the leads you
> >need.
>
> Close to 40 years ago there was an over-the-air UHF TV channel that I
> couldn't receive because I was (literally) in the shadow of a
> mountain.
>
> But 150' west in my back yard there was ample signal.
>
> So I ran 18-24V down the coax to varactor adjust a UHF tuner (after
> level-shifting), then a 12V linear regulator to run the tuner itself,
> and piped back IF on the coax.
>
> You just need to think through the filters to keep everything
> separated.
>
> ...Jim Thompson
> --

I must add that the correct value of the capacitor can be found out by the
following equation,<capacitor reactance for the given frequency must be
zero>;xc=1/(omega*c)where omega = 2*pi*f<f:frequency in
Hz,pi=3,14159,c:capacitance of the capacitor in Farad>so if you set xc=0 and
you'll get for UHF around 0.1nF, for VHF and FM 1 nF, and for AM 100
nF.Better get one at least of 1kV.The inductor reactance can of course be
calculated with Xl=(omega*L) and it should be XL->infinity (or at least
several Mohms) for the given frequency.

Hope this helps,

--
Tzortzakakis Dimitrios
major in electrical engineering,freelance electrician
542nd mechanized infantry batallion
dimtzort AT otenet DOT gr

18 May 2006 8:26 PM

Dave Martindale

"Tzortzakakis Dimitrios" <dimtz***@otenet.gr> writes:

>I must add that the correct value of the capacitor can be found out by the
>following equation,<capacitor reactance for the given frequency must be
>zero>;xc=1/(omega*c)where omega = 2*pi*f<f:frequency in
>Hz,pi=3,14159,c:capacitance of the capacitor in Farad>so if you set xc=0 and
>you'll get for UHF around 0.1nF, for VHF and FM 1 nF, and for AM 100
>nF.Better get one at least of 1kV.The inductor reactance can of course be
>calculated with Xl=(omega*L) and it should be XL->infinity (or at least
>several Mohms) for the given frequency.

It sounds like this little camera outputs *baseband* video, not RF. So
the video covers the frequency range 30 Hz-6 MHz or so. This is still
distinct from DC, so you can still run phantom power (video doesn't
need to maintain a DC reference, since the sync and blanking voltages
can be used as DC reference). But you'll need a much larger capacitor
to pass the 30 Hz AC component without significant impedance compared to
the 75 ohm load.

Dave

22 May 2006 1:23 AM

Joerg

Hello Jim,

>
> Close to 40 years ago there was an over-the-air UHF TV channel that I
> couldn't receive because I was (literally) in the shadow of a
> mountain.
>
> But 150' west in my back yard there was ample signal.
>
> So I ran 18-24V down the coax to varactor adjust a UHF tuner (after
> level-shifting), then a 12V linear regulator to run the tuner itself,
> and piped back IF on the coax.
>

A transistorized UHF tuner in 1966? With varicaps? Wow. Must have been
expensive, couldn't possibly have come out of a scrapped TV since just
before that they were all tubes and variable capacitors.

Was TV worth that effort back then? I remember as a kid Bonanza and
Lassie were good, and "All in the Family" of course. But all those hit
parades and talk shows? Nah.

Regards, Joerg

http://www.analogconsultants.com

22 May 2006 1:29 AM

Jim Thompson

On Mon, 22 May 2006 01:23:23 GMT, Joerg
<notthisjoerg***@removethispacbell.net> wrote:

Show quoteHide quote

>Hello Jim,
>
>>
>> Close to 40 years ago there was an over-the-air UHF TV channel that I
>> couldn't receive because I was (literally) in the shadow of a
>> mountain.
>>
>> But 150' west in my back yard there was ample signal.
>>
>> So I ran 18-24V down the coax to varactor adjust a UHF tuner (after
>> level-shifting), then a 12V linear regulator to run the tuner itself,
>> and piped back IF on the coax.
>>
>
>A transistorized UHF tuner in 1966? With varicaps? Wow. Must have been
>expensive, couldn't possibly have come out of a scrapped TV since just
>before that they were all tubes and variable capacitors.

So I can't count... it was more like 1977... almost _30_ years ago.

But I did _buy_ the tuner, but I don't recall where... it certainly
wasn't on the web ;-)

>
>Was TV worth that effort back then? I remember as a kid Bonanza and
>Lassie were good, and "All in the Family" of course. But all those hit
>parades and talk shows? Nah.
>
>Regards, Joerg
>
>http://www.analogconsultants.com

It was ON-TV, the encoded XXX channel ;-)

...Jim Thompson

--

I love to cook with wine. Sometimes I even put it in the food.

18 May 2006 5:05 PM

Don Bruder

In article <Xns97C75EFF5E909samthemanverizonnet@199.45.49.11>,
SamSez <samthe***@verizon.net> wrote:

Show quoteHide quote

> "raveneye" <junkmails***@bellsouth.net> wrote in
> news:1147957351.145739.278030@j73g2000cwa.googlegroups.com:
>
> > Thanks for your replies.
> >
> > I've tried contacting the manufacturer (in Taiwan) by email and phone,
> > but have not received any response, hence the post to this group. It
> > seems like a simple problem, all I would need is some kind of adapter
> > that separates out the video from the DC. I don't have the experience
> > to build one myself, unless there were some detailed step by step
> > instructions published somewhere.
> >
> >
>
> A google for "phantom camera power coax" will give you all the leads you
> need.

Didn't it get mentioned that this is the way they power the mid-span
amplifiers on Cable TV lines not too long ago?

--
Don Bruder - dak***@sonic.net - If your "From:" address isn't on my whitelist,
or the subject of the message doesn't contain the exact text "PopperAndShadow"
somewhere, any message sent to this address will go in the garbage without my
ever knowing it arrived. Sorry... <http://www.sonic.net/~dakidd> for more info

23 May 2006 1:55 AM

Michael A. Terrell

Don Bruder wrote:

>
> In article <Xns97C75EFF5E909samthemanverizonnet@199.45.49.11>,
> SamSez <samthe***@verizon.net> wrote:
>
> > A google for "phantom camera power coax" will give you all the leads you
> > need.
>
> Didn't it get mentioned that this is the way they power the mid-span
> amplifiers on Cable TV lines not too long ago?

Yes, except CATV line amps are powered by a 60 VAC 30 Amp CVT
transformer.

--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

8 Nov 2006 5:36 AM

ALBERT C. GOOD JR.

Don... you are exactly correct about this technique having been used to
power cable equipment. It used to be common practice in CCTV systems to
power antenna mounted equipment and security cameras this way.
It saved on construction costs in that the need for multiple 110v outlets
became unnecissisary.

Al.

Show quoteHide quote

"Don Bruder" <dak***@sonic.net> wrote in message
news:446ca94b$0$96964$742ec2ed@news.sonic.net...
> In article <Xns97C75EFF5E909samthemanverizonnet@199.45.49.11>,
> SamSez <samthe***@verizon.net> wrote:
>
> > "raveneye" <junkmails***@bellsouth.net> wrote in
> > news:1147957351.145739.278030@j73g2000cwa.googlegroups.com:
> >
> > > Thanks for your replies.
> > >
> > > I've tried contacting the manufacturer (in Taiwan) by email and phone,
> > > but have not received any response, hence the post to this group. It
> > > seems like a simple problem, all I would need is some kind of adapter
> > > that separates out the video from the DC. I don't have the experience
> > > to build one myself, unless there were some detailed step by step
> > > instructions published somewhere.
> > >
> > >
> >
> > A google for "phantom camera power coax" will give you all the leads you
> > need.
>
> Didn't it get mentioned that this is the way they power the mid-span
> amplifiers on Cable TV lines not too long ago?
>
> --
> Don Bruder - dak***@sonic.net - If your "From:" address isn't on my
whitelist,
> or the subject of the message doesn't contain the exact text
"PopperAndShadow"
> somewhere, any message sent to this address will go in the garbage without
my
> ever knowing it arrived. Sorry... <http://www.sonic.net/~dakidd> for more
info

8 Nov 2006 3:10 PM

Charles & Barbara Barker

fyi

ALBERT C. GOOD JR. wrote:
Show quoteHide quote

> Don... you are exactly correct about this technique having been used to
> power cable equipment. It used to be common practice in CCTV systems to
> power antenna mounted equipment and security cameras this way.
> It saved on construction costs in that the need for multiple 110v outlets
> became unnecissisary.
>
> Al.
>
>
> "Don Bruder" <dak***@sonic.net> wrote in message
> news:446ca94b$0$96964$742ec2ed@news.sonic.net...
>> In article <Xns97C75EFF5E909samthemanverizonnet@199.45.49.11>,
>> SamSez <samthe***@verizon.net> wrote:
>>
>>> "raveneye" <junkmails***@bellsouth.net> wrote in
>>> news:1147957351.145739.278030@j73g2000cwa.googlegroups.com:
>>>
>>>> Thanks for your replies.
>>>>
>>>> I've tried contacting the manufacturer (in Taiwan) by email and phone,
>>>> but have not received any response, hence the post to this group. It
>>>> seems like a simple problem, all I would need is some kind of adapter
>>>> that separates out the video from the DC. I don't have the experience
>>>> to build one myself, unless there were some detailed step by step
>>>> instructions published somewhere.
>>>>
>>>>
>>> A google for "phantom camera power coax" will give you all the leads you
>>> need.
>> Didn't it get mentioned that this is the way they power the mid-span
>> amplifiers on Cable TV lines not too long ago?
>>
>> --
>> Don Bruder - dak***@sonic.net - If your "From:" address isn't on my
> whitelist,
>> or the subject of the message doesn't contain the exact text
> "PopperAndShadow"
>> somewhere, any message sent to this address will go in the garbage without
> my
>> ever knowing it arrived. Sorry... <http://www.sonic.net/~dakidd> for more
> info
>
>

19 May 2006 7:27 AM

Jasen Betts

On 2006-05-18, raveneye <junkmails***@bellsouth.net> wrote:

> Thanks for your replies.
>
> I've tried contacting the manufacturer (in Taiwan) by email and phone,
> but have not received any response, hence the post to this group. It
> seems like a simple problem, all I would need is some kind of adapter
> that separates out the video from the DC. I don't have the experience
> to build one myself, unless there were some detailed step by step
> instructions published somewhere.

what you do is measure the paramters of the power unit and duplicate them

splitting the video out will probably be fairly easy.
but if you inject the power wrongly you'll destroy the camera.

it may be possible to use part of the AC-powered adaptor
but modifying it loses you the chance to use it as a
reference...

--

Bye.
Jasen

19 May 2006 11:20 PM

Don Lancaster

sinol***@charter.net wrote:

> Rolf wrote:
> The RF is isolated from the 12v DCon the center conductor with
> capasitors. The RF pass through the capasitors the DC does not.
>

.... and the impedance of the dc path normally may have to be raised by a
suitable resistor or inductor.

If the rf is 50 or 70 Ohms, raising the dc path impedance is no big deal.

--
Many thanks,

Don Lancaster                          voice phone: (928)428-4073
Synergetics   3860 West First Street   Box 809 Thatcher, AZ 85552
rss: http://www.tinaja.com/whtnu.xml   email: d**@tinaja.com

Please visit my GURU's LAIR web site at http://www.tinaja.com