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

 

[David Nebenzahl]

On 2/2/2009 4:03 PM letterman@invalid.com spake thus:

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?

#1: Bullshit, requiring no more explanation to anyone who knows anything
about electronics (inputs are inputs, outputs are outputs, etc.).

#2: True. Video is video. (S-video, I b'leeves, although I could be
shown to be wrong on that.)


--
Personally, I like Vista, but I probably won't use it. I like it
because it generates considerable business for me in consulting and
upgrades. As long as there is hardware and software out there that
doesn't work, I stay in business. Incidentally, my company motto is
"If this stuff worked, you wouldn't need me".

- lifted from sci.electronics.repair

 

[Dave Plowman (News)]

In article <im1fo41ehogkghvdojpr0p2ijje7n6pob4@4ax.com>,
<letterman@invalid.com> wrote:

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.

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.

--
*Who are these kids and why are they calling me Mom?

Dave Plowman dave@davenoise.co.uk London SW
To e-mail, change noise into sound.

 

[William Sommerwerck]

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).

 

[Rich Webb]

On Mon, 02 Feb 2009 18:03:07 -0600, letterman@invalid.com wrote:

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.

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.

--
Rich Webb Norfolk, VA

 

[Jeff Liebermann]

On Mon, 02 Feb 2009 18:03:07 -0600, letterman@invalid.com wrote:

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.

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.

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

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).

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

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.
<http://electronics.howstuffworks.com/hd-upconverter.htm>

I also heard that a DTV converter can be connected to a computer
monitor rather than a tv.

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.

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?

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

--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

 

[William R. Walsh]

Hi!

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

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.

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,

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

 

[William R. Walsh]

Hi!

couple

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

 

On Thu, 05 Feb 2009 05:03:51 GMT, "William R. Walsh"
<newsgroups1@idontwantjunqueemail.walshcomptech.com> wrote:

Hi!

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

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 sounds like a good idea. I wonder how far it would transmit?
I am on a farm, and very far from tv stations. It would be nice to
broadcast from the house so I could watch tv in the barn or garage.
Right now I can barely get stations in those out buildings, using only
rabbit ears. I cant justify putting roof antennas on all buildings.

The buildings are all within a maximum of 250 ft from the house.

Of course for what you are saying, I'd need 2 antennas on the house,
one to receive, and one to transmit, right?

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,

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.

Those are all RCA plugs, right?
It used to be yellow was video, and red/white audio L+R.
These says they have a plug of almost every color under the sun.
I have never learned what they are all for.

William

By the way, you mentioned 75 ohm tv coax. I'm not planning to do it,
but what would happen if someone used some 50 ohm coax made for CB
radios (and I think Ham too)?
Just curious because they both look darn near the same.....

LM

 

On Thu, 05 Feb 2009 05:10:51 GMT, "William R. Walsh"
<newsgroups1@idontwantjunqueemail.walshcomptech.com> wrote:

Hi!

couple

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

I thought thats what you meant......

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.

I've seen those advertised, never seen one in action though.

I've heard that you can put the tv picture in a small window on the
desktop.

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.

That's a pretty wild sort of thing. I never heard of such a device.
I've also heard some of the newer tv sets can be used as a computer
monitor. But I cant understand how to connect them. Does the tv have
a vga connector or so the newest computers have a AV outputs? My 8
year old computer dont have any of that stuff.

I've always wanted to take a laptop computer to a friends house, plug
it into their tv, and show them my digital photos. If they got a
computer, I can just use their monitor, but for example, my elderly
relatives dont have computers, and I dont print most photos like they
did in the film days.

William

 

[Dave Plowman (News)]

In article <gs6no4l57951t46m3ha4oc36o26oetjs37@4ax.com>,
<letterman@invalid.com> wrote:

That sounds like a good idea. I wonder how far it would transmit?
I am on a farm, and very far from tv stations. It would be nice to
broadcast from the house so I could watch tv in the barn or garage.
Right now I can barely get stations in those out buildings, using only
rabbit ears. I cant justify putting roof antennas on all buildings.

The buildings are all within a maximum of 250 ft from the house.

Of course for what you are saying, I'd need 2 antennas on the house,
one to receive, and one to transmit, right?

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.

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

Dave Plowman dave@davenoise.co.uk London SW
To e-mail, change noise into sound.

 

[Dave Plowman (News)]

In article <vb7no41tm4eneu8630npa20lemoiesa0o0@4ax.com>,
<letterman@invalid.com> wrote:

I've also heard some of the newer tv sets can be used as a computer
monitor. But I cant understand how to connect them. Does the tv have
a vga connector or so the newest computers have a AV outputs? My 8
year old computer dont have any of that stuff.

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. ;-)

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

Dave Plowman dave@davenoise.co.uk London SW
To e-mail, change noise into sound.

 

[William R. Walsh]

Hi!

(TV tuner PCI card)

I've seen those advertised, never seen one in action
though.

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)

That's a pretty wild sort of thing.  I never heard of
such a device.

http://www.walshcomptech.com/ohlandl/video/PS2_TV.html

I've also heard some of the newer tv sets can be used
as a computer monitor.  But I cant understand how to
connect them.  Does the tv have a vga connector or so
the newest computers have a AV outputs?

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.

I've always wanted to take a laptop computer to a
friends house, plug it into their tv, and show them
my digital photos.

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

 

[William R. Walsh]

Hi!

That sounds like a good idea.  I wonder how far it would
transmit?

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.

Of course for what you are saying, I'd need 2 antennas
on the house, one to receive, and one to transmit,
right?

Yes, ideally. I've never tried it.

Those are all RCA plugs, right?

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.)

By the way, you mentioned 75 ohm tv coax.  I'm not
planning to do it, but what would happen if someone
used some 50 ohm coax made for CB radios (and I think
Ham too)?

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

 

[Twayne]

Rich Webb wrote:

On Mon, 02 Feb 2009 18:03:07 -0600, letterman@invalid.com wrote:

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.

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.

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<g>.

 

[Gnack Nol]

On Fri, 06 Feb 2009 12:57:45 -0500, Twayne wrote:

Rich Webb wrote:
On Mon, 02 Feb 2009 18:03:07 -0600, letterman@invalid.com wrote:

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.

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.

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<g>.

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

 

[Samuel M. Goldwasser]

Gnack Nol <mchozfcesujcfc@mailinator.com> writes:

On Fri, 06 Feb 2009 12:57:45 -0500, Twayne wrote:

Rich Webb wrote:
On Mon, 02 Feb 2009 18:03:07 -0600, letterman@invalid.com wrote:

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.

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.

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<g>.

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.

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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