Driving 1,000 computer monitors?

[Terry Collins]

How?

Actually, what jargon should I use to search for circuits to build.


The background is that I do work for a community group that re-uses old
computers and we currently have premises in an arts centre. Our "rent"
is basically technical knowledge and assistance to support vqarious
"artistic" projects.

This one comes out a project that will be a wall of computer monitors
(db15 plug driven) all showing the same image, so my understanding says
that we are going to need an amplifier and splitters or
splitter-amplifier, preferrably with the least number of stages.

Hence, my question for assistance in what jargon I should plug into
search engines.

This is basically for the mathematics of costing the construction of the
video splitters, etc.

TIA.

 

[Michael A. Terrell]

Terry Collins wrote:

How?

Actually, what jargon should I use to search for circuits to build.

The background is that I do work for a community group that re-uses old
computers and we currently have premises in an arts centre. Our "rent"
is basically technical knowledge and assistance to support vqarious
"artistic" projects.

This one comes out a project that will be a wall of computer monitors
(db15 plug driven) all showing the same image, so my understanding says
that we are going to need an amplifier and splitters or
splitter-amplifier, preferrably with the least number of stages.

Hence, my question for assistance in what jargon I should plug into
search engines.

This is basically for the mathematics of costing the construction of the
video splitters, etc.

TIA.

The proper term is "Video Distribution Amplifier" There are plenty
of commercial units, as well as chips designed for this application.
The biggest problem will be cable lengths causing roll off of higher
frequencies. National. maxim and others make suitable chips for the
project.

--
Link to my "Computers for disabled Veterans" project website deleted
after threats were telephoned to my church.

Michael A. Terrell
Central Florida

 

[John Mackesy]

Terry Collins wrote:

How?

Actually, what jargon should I use to search for circuits to build.


The background is that I do work for a community group that re-uses old
computers and we currently have premises in an arts centre. Our "rent"
is basically technical knowledge and assistance to support vqarious
"artistic" projects.

This one comes out a project that will be a wall of computer monitors
(db15 plug driven) all showing the same image, so my understanding says
that we are going to need an amplifier and splitters or
splitter-amplifier, preferrably with the least number of stages.

Hence, my question for assistance in what jargon I should plug into
search engines.

This is basically for the mathematics of costing the construction of the
video splitters, etc.

TIA.

I've seen something like this using TV sets? video monitors? at a
shopping centre, only they formed 1 *BIG* picture. I'd suggest it'd be
cheaper/easier to use TV's and you'd get the same result.

John Mackesy

 

[Phil Allison]

"Terry Collins"

The background is that I do work for a community group that re-uses old
computers and we currently have premises in an arts centre. Our "rent" is
basically technical knowledge and assistance to support vqarious
"artistic" projects.

This one comes out a project that will be a wall of computer monitors
(db15 plug driven) all showing the same image, so my understanding says
that we are going to need an amplifier and splitters or
splitter-amplifier, preferrably with the least number of stages.

Hence, my question for assistance in what jargon I should plug into search
engines.

This is basically for the mathematics of costing the construction of the
video splitters, etc.

** Are you serious ?????

***1000*** monitors ???

The average monitor draws circa 0.5 amps rms from the supply - so 1000 of
them means 500 amps !!!!!!!!

Even with 3-phase that load is 170 amps per phase - with no neutral
current cancellation !!!!!!!

Monitors have large switch on surges too - circa 50 amps peak EACH !!!!





........... Phil

 

[David L. Jones]

Terry Collins wrote:

How?

Actually, what jargon should I use to search for circuits to build.


The background is that I do work for a community group that re-uses old
computers and we currently have premises in an arts centre. Our "rent"
is basically technical knowledge and assistance to support vqarious
"artistic" projects.

This one comes out a project that will be a wall of computer monitors
(db15 plug driven) all showing the same image, so my understanding says
that we are going to need an amplifier and splitters or
splitter-amplifier, preferrably with the least number of stages.

Hence, my question for assistance in what jargon I should plug into
search engines.

This is basically for the mathematics of costing the construction of the
video splitters, etc.

TIA.

You want a video distribution amplifier, and one with the maximum
number of outputs possible. Something like this:
http://www.networktechinc.com/vsplt-pc.html

What you want to do is try to minimise the number of cascaded units. So
if you have one with 10 outputs, you'll need to casacde an array of 3
of these boxes in series to get 1000 outputs. You have to make sure it
can do this at the bandwidth you need.
What resolution and frame rate are you thinking of using?, this may
have a large impact on the number of units you can cascade without
problem.
Shouldn't be too hard if you are using a low-ish resolution and refresh
rate, say 800x600 and <=60Hz.

I designed a system once which drove hundreds of flat screen monitors,
and it could have done thousands, but this was in the digital domain,
direct LCD output.

A commercial solution might be very expensive, so a custom solution
could be the go. You need some triple channel video buffer chips, and
I'm sure there are ones specicially designed for RGB/VGA buffering,
dont' have the details to hand though.

Dave

 

[Terry Collins]

John Mackesy wrote:

Our
"rent" is basically technical knowledge and assistance to support
vqarious "artistic" projects.

I've seen something like this using TV sets? video monitors? at a
shopping centre, only they formed 1 *BIG* picture. I'd suggest it'd be
cheaper/easier to use TV's and you'd get the same result.

Umm, this is "art", you know, here today, gone tomorrow, faster than a
movie set. so, there is no/absolute minimal budget. (hmm, anyone know of
a movie set that needs something like this).

And since we pass on computer monitors, they are "free", plus, the local
supplier of "TVs" has just soiled his pants on supplying reliable goods
(only 3 out of 20 worked - of course artist didn't test on delivery did he).

So, we have said we can give them to him, one way trip, absolutely no
returns will be considered for any reason. This is a future project, so
we can pass on our surplus.

 

[Terry Collins]

Phil Allison wrote:

"Terry Collins"
vqarious "artistic" projects.

** Are you serious ?????

He is.

***1000*** monitors ???

The average monitor draws circa 0.5 amps rms from the supply - so 1000 of
them means 500 amps !!!!!!!!

Even with 3-phase that load is 170 amps per phase - with no neutral
current cancellation !!!!!!!

Yep, one of our number has already done this dance, but as I said, it is
all just mathematics, HIS.

And we have already had the first discussion session with him and
pointed out that he will need to do a lot of calculations on electricity
demands, weight and the scaffolding to support it, plus make sure the
floor will support it (and no I don't think that your or my welding
skills are good enough to make a scaffold), etc, etc,

Monitors have large switch on surges too - circa 50 amps peak EACH !!!!

Well, this is where we can advise him about staging the switch on, but
did you mean 5 amp?

Now, the good news is that the hall in which he wants to do it has at
least 6 three phase outlets and he knows he has to check circuit
numbers, plus he has already asked the site electrician to come and talk
to him.

I hope it is in winter, then the concrete mausoleum will not need the 12
radiant heaters is has for this space {

 

[Phil Allison]

"Terry Collins"

Phil Allison wrote:


** Are you serious ?????

He is.

***1000*** monitors ???

The average monitor draws circa 0.5 amps rms from the supply - so 1000
of them means 500 amps !!!!!!!!

Even with 3-phase that load is 170 amps per phase - with no neutral
current cancellation !!!!!!!

Yep, one of our number has already done this dance, but as I said, it is
all just mathematics, HIS.

** The excess neutral current will be a major problem.

The rms value is 1.73 ( sqrt 3 ) times the phase currents.

And we have already had the first discussion session with him and pointed
out that he will need to do a lot of calculations on electricity demands,
weight and the scaffolding to support it, plus make sure the floor will
support it (and no I don't think that your or my welding skills are good
enough to make a scaffold), etc, etc,


Monitors have large switch on surges too - circa 50 amps peak EACH !!!!

Well, this is where we can advise him about staging the switch on, but did
you mean 5 amp?

** No ** 50 ** amps.

Besides the PSU caps, there is a little horror called a "degaussing coil"
which goes " thump" when you turn any colour CRT on. Basically a coil of
copper wire with a few ohms resistance being driven directly by 240 volts
AC, for a few cycles.

Now, the good news is that the hall in which he wants to do it has at
least 6 three phase outlets and he knows he has to check circuit numbers,
plus he has already asked the site electrician to come and talk to him.

** No ordinary electrician is going to know about CRTs, surge currents or
the neutral disaster. Poker machines in clubs present similar powering
problems - AC ccts in RSLs can only be run at a fraction of nominal load
due to the "Ode" each night.

I hope it is in winter, then the concrete mausoleum will not need the 12
radiant heaters is has for this space {

** The whole idea is utterly bonkers.





............. Phil

 

[FruitLoop]

"Phil Allison" <philallison@tpg.com.au> wrote in message
news:3mtv5dF18ppgkU1@individual.net...

"Terry Collins"
Phil Allison wrote:


** Are you serious ?????

He is.

***1000*** monitors ???

The average monitor draws circa 0.5 amps rms from the supply - so 1000
of them means 500 amps !!!!!!!!

Even with 3-phase that load is 170 amps per phase - with no neutral
current cancellation !!!!!!!

Yep, one of our number has already done this dance, but as I said, it is
all just mathematics, HIS.


** The excess neutral current will be a major problem.

Thats bullshit , if the 3 phase load is close to balanced then the neutral
technically can be floating .

The rms value is 1.73 ( sqrt 3 ) times the phase currents.


And we have already had the first discussion session with him and
pointed
out that he will need to do a lot of calculations on electricity
demands,
weight and the scaffolding to support it, plus make sure the floor will
support it (and no I don't think that your or my welding skills are good
enough to make a scaffold), etc, etc,


Monitors have large switch on surges too - circa 50 amps peak EACH
!!!!

Well, this is where we can advise him about staging the switch on, but
did
you mean 5 amp?


** No ** 50 ** amps.

Besides the PSU caps, there is a little horror called a "degaussing coil"
which goes " thump" when you turn any colour CRT on. Basically a coil
of
copper wire with a few ohms resistance being driven directly by 240 volts
AC, for a few cycles.



Now, the good news is that the hall in which he wants to do it has at
least 6 three phase outlets and he knows he has to check circuit
numbers,
plus he has already asked the site electrician to come and talk to him.


** No ordinary electrician is going to know about CRTs, surge currents or
the neutral disaster. Poker machines in clubs present similar powering
problems - AC ccts in RSLs can only be run at a fraction of nominal load
due to the "Ode" each night.


I hope it is in winter, then the concrete mausoleum will not need the 12
radiant heaters is has for this space {


** The whole idea is utterly bonkers.





............ Phil

 

[Terry Collins]

David L. Jones wrote:

You want a video distribution amplifier, and one with the maximum
number of outputs possible. Something like this:
http://www.networktechinc.com/vsplt-pc.html

Thanks. Looking at the $$$ I can see this project being radically
changed. Well, the last one was to have 20 monitors & x speakers
rotating on a clothes line, but it settled for a static wall on TV's {.

What you want to do is try to minimise the number of cascaded units. So
if you have one with 10 outputs, you'll need to casacde an array of 3
of these boxes in series to get 1000 outputs. You have to make sure it
can do this at the bandwidth you need.
What resolution and frame rate are you thinking of using?, this may
have a large impact on the number of units you can cascade without
problem.
Shouldn't be too hard if you are using a low-ish resolution and refresh
rate, say 800x600 and <=60Hz.

This is his problem. We can pass on your comments. Thanks. They are sort
of what we have said. Basically, we have offered to supply 14" & 15"
monitor, so I expect most will be low end resolution anyway. It is just
whether they have the same/compatible resolution, but that is his problem.

If he gives us a spec, then it is simple to build a testing computer
locked at that resolution,

I designed a system once which drove hundreds of flat screen monitors,
and it could have done thousands, but this was in the digital domain,
direct LCD output.

A commercial solution might be very expensive,

I don't think it counts as art if you can just buy it.
Actually, I personally would not call the project art as it has a
commercial solution, but then the "art" may be in what is in the video
images.

so a custom solution could be the go.

And good learning for me. {

You need some triple channel video buffer chips, and
I'm sure there are ones specicially designed for RGB/VGA buffering,
dont' have the details to hand though.

I can hunt around and see what I can find. I don't mind doing a bit of
investigating for amusement, but the materials for trialling will
definitely be funded for this, besides I already have my video splitter
{.

 

[Phil Allison]

"FruitLoop"
"Phil Allison"

***1000*** monitors ???

The average monitor draws circa 0.5 amps rms from the supply - so
1000
of them means 500 amps !!!!!!!!

Even with 3-phase that load is 170 amps per phase - with no neutral
current cancellation !!!!!!!

Yep, one of our number has already done this dance, but as I said, it
is
all just mathematics, HIS.


** The excess neutral current will be a major problem.

Thats bullshit , if the 3 phase load is close to balanced then the neutral
technically can be floating .

** You must be a mug electrician as well as a fruit loop.

The rms value of the neutral current when the load wholly electronic is
1.73 ( sqrt 3 ) times the phase currents.

The is simply no cancellation in the neutral.





............ Phil

 

[Terry Collins]

Phil Allison wrote:

** The whole idea is utterly bonkers.

Phil, it is art, Phil ART!

ROFL. I know it sounds absolutely crackpot, but that is what makes an
artist. At least what he does is mildy technically interesting, rather
than a pile of vomitous verbal wanking.


P.S. I can recommend Sculture by the Sea for a bit of a laugh each year.

 

[FruitLoop]

"Phil Allison" <philallison@tpg.com.au> wrote in message
news:3mu0qvF18gk1eU1@individual.net...

"FruitLoop"
"Phil Allison"


***1000*** monitors ???

The average monitor draws circa 0.5 amps rms from the supply - so
1000
of them means 500 amps !!!!!!!!

Even with 3-phase that load is 170 amps per phase - with no
neutral
current cancellation !!!!!!!

Yep, one of our number has already done this dance, but as I said, it
is
all just mathematics, HIS.


** The excess neutral current will be a major problem.

Thats bullshit , if the 3 phase load is close to balanced then the
neutral
technically can be floating .



** You must be a mug electrician as well as a fruit loop.

Na , Im a rocket scientist , more interesting than a lowlife electrician

The rms value of the neutral current when the load wholly electronic is
1.73 ( sqrt 3 ) times the phase currents.

The is simply no cancellation in the neutral.

What about the 120 degree phase seperation . Also I have seen 3 phase power
single phase systems with the neutral fully floating and not connected . For
this to work a balanced 3 phase load is required + a common star point
connection on a transformer . So go root your boot a neutral isnt even
required .

........... Phil

 

[Phil Allison]

"FruitLoop" = one king size, moronic pig

Na , Im a rocket scientist , more interesting than a lowlife electrician

** Must be one of them former Nazi types - eh ???

The rms value of the neutral current when the load wholly electronic is
1.73 ( sqrt 3 ) times the phase currents.

The is simply no cancellation in the neutral.


What about the 120 degree phase seperation . Also I have seen 3 phase
power
single phase systems with the neutral fully floating and not connected .
For
this to work a balanced 3 phase load is required + a common star point
connection on a transformer . So go root your boot a neutral isnt even
required .

** No point even trying to inform this anencephalic POS about anythig.

Wanna bet the anonymous cretin is an apprentice ???




........... Phil

 

[FruitLoop]

"Phil Allison" <philallison@tpg.com.au> wrote in message
news:3mvp31F18sib1U1@individual.net...

"FruitLoop" = one king size, moronic pig

And your normal , hahahahahahahahahaha

Na , Im a rocket scientist , more interesting than a lowlife electrician



** Must be one of them former Nazi types - eh ???



The rms value of the neutral current when the load wholly electronic is
1.73 ( sqrt 3 ) times the phase currents.

The is simply no cancellation in the neutral.


What about the 120 degree phase seperation . Also I have seen 3 phase
power
single phase systems with the neutral fully floating and not connected .
For
this to work a balanced 3 phase load is required + a common star point
connection on a transformer . So go root your boot a neutral isnt even
required .



** No point even trying to inform this anencephalic POS about anythig.

Wanna bet the anonymous cretin is an apprentice ???

Yep even a modern day apprentice is smarter than you phillis .
Hahahahahahaha

.......... Phil

 

[Phil Allison]

"FruitLoop" <Hyperactive@fruitloop.net>


** Must be one of them former Nazi types - eh ???

No point even trying to inform this anencephalic POS about anything.

Wanna bet the anonymous cretin is a failed apprentice male whore ???





............ Phil

 

[FruitLoop]

"Phil Allison" <philallison@tpg.com.au> wrote in message
news:3n04koF18nuhjU1@individual.net...

"FruitLoop" <Hyperactive@fruitloop.net


** Must be one of them former Nazi types - eh ???

No point even trying to inform this anencephalic POS about anything.

Wanna bet the anonymous cretin is a failed apprentice male whore ???





........... Phil

 

[FruitLoop]

"Phil Allison" <philallison@tpg.com.au> wrote in message
news:3n04koF18nuhjU1@individual.net...

"FruitLoop" <Hyperactive@fruitloop.net


** Must be one of them former Nazi types - eh ???

No point even trying to inform this anencephalic POS about anything.

Wanna bet the anonymous cretin is a failed apprentice male whore ???

BECAUSE YOU HAVE BEEN JUST FUCKED OVER ... AGAIN

........... Phil

 

[Phil Allison]

"FruitLoop" <Hyperactive@fruitloop.net>

"Phil Allison"


** No point even trying to inform this anencephalic POS about anything.

Wanna bet this autistic cretin has failed his apprenticeship as a male whore
???

BECAUSE YOU HAVE BEEN JUST FUCKED OVER ... AGAIN

** ROTFL !!!


By his own words is he condemned ......




......... Phil

 

[Roger Lascelles]

"FruitLoop" <Hyperactive@fruitloop.net> wrote in message
news:GWjOe.7337$FA3.6575@news-server.bigpond.net.au...

** The excess neutral current will be a major problem.


Thats bullshit , if the 3 phase load is close to balanced then the neutral
technically can be floating .

Phil's post seems valid to me.

This article mentions the non-balanced neutral problem.

http://www.jmwa.demon.co.uk/EMCLF0010.htm

3 phase balancing works when the loads draw sinusoidal current. Computer
monitors have bridge rectifiers across the mains input, which charge
capacitors with short pulses of current near the peaks of the sinewave. So
the phases see large amplitude, narrow current pulses - at 120 degree timing
with little neutral cancellation - so the neutral wire is working very hard.

Roger Lascelles