Coaxial cable to video sensor: sending DC 12V?

[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!

 

[Pooh Bear]

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

 

[[email protected]]

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.

 

[Pooh Bear]

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

 

[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.

 

[SamSez]

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.

 

[Jim Thompson]

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

 

[Don Bruder]

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 Lancaster]

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.



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Synergetics 3860 West First Street Box 809 Thatcher, AZ 85552
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[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

 

[Jim Thompson]

Hello Jim,


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

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

...Jim Thompson

 

[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.

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

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