Hooking up a DTV converter backwards

OK, I am not buying this, but I read in a discussion group that if a person hooks up a DTV converter backwards, the result will be an analog signal that is broadcast into the home or to any tv within a small distance from the converter.

First it would take some serious modifications to connect it backwards, then I dont thing these converters are actually transmitters.

But I'll remain open minded until this is proved wrong.

I also heard that a DTV converter can be connected to a computer monitor rather than a tv. This one I'll consider a good possibility, IF they make monitors with a VIDEO input, (as in RCA connector). I have not shopped for a monitor for years, so maybe the new ones do have these connectors. My old CRT monitor only has the standard SVGA input connector that if I recall, has 15 pins.

So, maybe there is some truth to this, although an external sound system will be needed for the audio, which I'm sure any stereo receiver or amp will work.

Anyone know any truth to these things?

LM

Reply to
letterman
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Look up the spec of the monitor. In the UK most won't work at TV line and frame frequencies - they're too low. You can buy video to VGA convertors, though - but good ones ain't cheap.

Conversely, TV sets with a VGA input seem to work ok at most common computer resolutions - although perhaps not the higher ones.

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    Dave Plowman        dave@davenoise.co.uk           London SW 
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Reply to
Dave Plowman (News)

This is like saying that if you shine a bright light on a fluorescent tube, the tube will produce an output voltage.

Broadly speaking, an input (output) cannot magically become an output (input).

Reply to
William Sommerwerck

Well, one could certainly take the RF output from the converter box and run it into a splitter and then to two or several separate analog sets over coax.

One could also connect that RF-out jack to an antenna instead and so "broadcast" it. However, transmission antennas require more thought and design than just hooking up an old set of rabbit ears. And, by operating an "intentional radiator," FCC issues come into play. Unlicensed transmitters are frowned upon, although there are exceptions based on the band being used and the output power.

If you want to run multiple sets off of a single converter box (quite a reasonable thing to do) then the coax + splitter (possibly an amplified one) is probably the best way to go about it.

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Rich Webb     Norfolk, VA
Reply to
Rich Webb

Muddle. Some DTV to analog TV converters may have RF video modulators, with a channel 3 or 4 output, for those ancient TV's without RGB or component video inputs. The video modulator is usually connected in parallel with the NTSC video output jack allowing simultaneous operation. If you connected such a DTV converter to an antenna, and then attached another antenna to the RF channel 3 or 4 output, you will have a short range TV transmitter. This is not exactly connecting the DTV converter "backwards" but might be what you were reading.

Don't forget to connect the power supply leads backwards. If you don't produce RF, at least it will produce smoke. (Don't do it).

The only part that's wrong is the "backwards". The DTV to analog TV is a one way process. There are "upconverters" that will display an ordinary DVD video on an HDTV in 1080i resolution, but that's not included in the common DTV to analog converter box.

Muddle 2.0. Depends on the monitor. The DTV converter has RGB, component, Svideo, and possibly RF output. If your comptuah monitor has any of these available as inputs, it should work. More likely, a typical HDTV will have all these inputs, and can be used as a computah monitor, TV set, or whatever else available. Check the available inputs and that's what can be viewed.

Partial truths. Some clue as to the maker and model number of the DTV converter in question might be helpful.

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Jeff Liebermann     jeffl@cruzio.com
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Reply to
Jeff Liebermann

Hi!

Not really. Not only is there the 75 ohm coaxial connector for input, but most of them also have an identical looking connector for RF output in addition to composite or S-Video output.

That RF output is a small, extremely low power modulator that outputs to TV channel 3 or 4. It would not be impossible to hook it up improperly, get some digital TV reception from the length of coaxial cable connected to the antenna input and have that be rebroadcast "out" to the antenna, where it might travel a short distance and be receivable by other TVs. The harm it would do would be minimal and the cable swap would probably be corrected quickly when the person doing the work discovered their own set did not work properly.

That depends upon the monitor. None of the couple eligible converters will offer anything like that, although some higher end models might. Some monitors can accept composite or S-video input alongside the VGA or DVI inputs they also have.

William

Reply to
William R. Walsh

Hi!

should read "coupon". Guess my mind was somewhere else.

It's also worth mentioning that one way you could watch TV on your computer screen is with a TV tuner expansion card. Some computers have these installed from the factory, or you can add one. I have been using a Zenith converter box with my ATI TV Wonder PCI, and it works fine...although right now it's hooked up to the RF modulator on the converter and so I don't get stereo sound any more.

Dedicated boxes have also been sold with a TV tuner at one end and a 15-pin VGA connector at the other. I have one of those as well. It actually "taps" into the keyboard cable and TV can be called up with a special keystroke. It's also possible to watch TV in a window with it, as it comes with some software that draws a window of a certain color that the hardware will find and place the TV image in.

William

Reply to
William R. Walsh

You can buy 'RF senders' designed to transmit video and audio locally on broadcast frequencies that can be picked up by any analogue TV which I'd guess would have a higher output than a modulator. Try Ebay. Not sure about the legality of them, though.

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*If a pig loses its voice, is it disgruntled?

    Dave Plowman        dave@davenoise.co.uk           London SW
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Reply to
Dave Plowman (News)

I have one of these in my workshop so I can use files I may need from my computer at the workbench. It has a VGA type connector. I've used a VGA distribution amp so both the computer monitor and the 'TV' can display the computer output at the same time - to save having to replug things. My computer there is even older than yours and not even a PC. So doesn't have AV outputs either. One interesting point is the TV as monitor has a much wider range of resolutions than a modern monitor which can be useful for some older computers. I've been able to run some old games that use TV resolutions I haven't been able to see for years. ;-)

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*All men are idiots, and I married their King.

    Dave Plowman        dave@davenoise.co.uk           London SW
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Reply to
Dave Plowman (News)

Hi!

(TV tuner PCI card)

They actually work pretty well, for the most part. And most of them can record. Some even have hardware assisted recording, using a dedicated processor on the card.

You can watch the TV in a window, put it on your whole screen, or in the case of the ATI TV Wonder I've got, use "video wallpaper".

I recently bought one that has an ATSC (digital broadcast TV) tuner built into it. It works nicely.

(dedicated TV box for computer)

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It can work either way. Recent TVs typically have high quality display that are also suitable for high resolution computer use, so they may have a VGA, DVI or other computer display connector on board.

For older TVs (which may not be so good for high resolution use), the computer may have a TV output on its video card.

Many laptops have an onboard TV encoder that can display a picture on a regular TV. You might need an extra cable to be able to use it, though. You would also need to be able to turn it on, something that would be an option in the control panel software for your laptop's video system.

William

Reply to
William R. Walsh

Hi!

I don't think it would get any further than maybe 50-100 feet from the antenna. Anything in the way might reduce that range significantly.

And it's not really legal to do it, although if you are out in the middle of nowhere with nobody around I doubt anyone would mind or even notice.

My only real concern is that the little RF modulator in your converter box might not be up to driving an antenna. That risk is likely to be small, however.

Yes, ideally. I've never tried it.

Composite video comes on a yellow plug with this type of equipment. Audio right and left are red and white as you said.

S-Video is a four pin round connector with a key so you can't plug it in the wrong way. It doesn't provide audio.

The other ones (green, blue and others) are for use with higher end equipment and typically separate out the color information and sync signals. They should be labeled as to what they do, or you'd match the colors with the plugs on your TV.

(This is a US-based perspective on the subject. If you're outside of the US, you may have other connectors to choose from, such as SCART.)

For something non-critical and simple like this, it would probably work acceptably well.

For the buildings on your farm, you might be better served by a "video sender". These have been on the market for a while. You plug one into the device playing video, and plug the other one into a TV. These are legal, operate in the 2.4GHz band for the most part, and actually offer a pretty good operating range. Some even relay remote control signals to the device providing the video.

William

Reply to
William R. Walsh

Have you seen/tried that? I'd expect standing waves to immediately trash any chance of anything being radiated and under the right circumstances blowing the ouput components.

Interesting concept, but ... BTW, reason I'm fairly sure is my neighbor tried to do something similar with an 80 dB amp from RS. It did a whole lot of nuttin' and then wouldn't work when he tried to put it back to watch TV. I'm guessing that he built a great standign wave generator.

Reply to
Twayne

While hooking up many of the old discrete UHF tuners defiantly worked backwards as a vhf / uhf up converter. Analog modulators had no way of up conversion since they contained no descrete local conversion oscillator / mixer to mix the signals. This I know having played with the modulator modules that are used to generate the ch 3-4 output. It has signal return blocking diodes to prevent leakage back to the antenna built into the switching circuit.

Dtv converters on the other hand are very sophisticated digital electronic packages and no doubt the possibility of this working is a figure of about a billion to the negative since very few digital decoding circuits have encoding functionality. I will not totally rule out the possibility of an IC that does both but it would not be cheap enough to go into these cheap converters.

So until someone can provide actual proof of models that work this way and it is reproducable by anyone I'll put this one on the shelf with the old fashoned snake oil ads and cold fusion.

Gnack

Reply to
Gnack Nol

Probability equals exactly .000000000000000000000000....

The encoding process is far more complex than the decoding process so one can be sure that it won't be there by accident.

And even if it was present in the circuitry, hooking electronics up backwards rarely does anything useful - this assuming it doesn't actually smoke. :)

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Reply to
Samuel M. Goldwasser

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