Coaxial cable to video sensor: sending DC 12V?

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

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

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.

"raveneye" wrote in news: snipped-for-privacy@j73g2000cwa.googlegroups.com:

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

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

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...

... 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.

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.

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

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 ;-)

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

...Jim Thompson

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

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.

whitelist,

"PopperAndShadow"

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