Running an extra signal to a projector...

[potsy]

Hello all,

Quite by accident the other day I bought a projector on ebay, but I didn’t really think about how I would feed it. Predictably, it has analogue inputs while my computer has digital outputs. I run two monitors from a fanless NVidia Gforce 7600GS and I’m trying to think of a way to duplicate what goes to one monitor and send it to the projector.

I tried just using a splitter, like this one link because I read somewhere that the digital output on a graphics card also carries an analogue signal (just on different pin outs). But it didn’t work – the splitter did pass signal to an analogue monitor, but it wouldn’t drive two monitors. Although I had guessed you might need to boost the signal to do that, I thought I’d give it a crack anyway because it’s cheap.

So I think my options are:

1. Get a new card with 2 analogue outputs and buy an active splitter like this one:link

2. Just get a new card, keep the 7600 and set it up so the computer has 3 monitor outputs.

I’m attracted to option 1 because:

1. I run a reasonably low power/heat system with only one 12mm fan, so I’d rather not have two cards in there. I only have a 200w power supply and another card means more noise (which is why I’m asking this question here right!); and

2. The projector will be off most of the time. Maybe I’m wrong about this, but I’ve found that when you unplug one monitor from a multi monitor set up, the system reconfigures itself and when you plug that monitor back in you have to set it up again. I don’t want to have to reconfigure a 3 monitor set up every time I use the projector.

I should also say I run Protools (7.4). I have one annoying glitch which the Digidesign forums indicate is probably due to an incompatibility between Protools and the NVidia card. The 7600 is otherwise fine for my needs and doesn’t suck much power (like about 30W: xbitlabs review. But I’d be happy enough to have an excuse to upgrade.

So, questions:

1. Is there a way around it that I haven’t thought of (like, is there a cheap active splitter that will split a digital signal into two analogue signals, or one digital and one analogue)?

2. Any recommendations for an ATI card with two analogue outputs, low power (but ok for some low end gaming) which is either fanless or compatible with the Scythe Musashi cooler?

3. On some sites an active splitter is quite expensive, like over $200. Anybody have a view about whether the $20 ebay version is junk which should be avoided?

Thanks heaps,
Potsy

[psyopper]

From looking around the web the 7600GS supported DVI, DSub and SVideo. From your description of the problem you are trying to pull the analog signal out of the DVI connector to send to the projector on a DSub cable. You also stated that you wantoed to duplicate one of the outputs...

Does your GS have 2 DVI ports? Or am I only slightly understanding that you want the monitor to be on a third output?

On signal duplication... Whenever you want to duplicate a signal it's always smartest (though not as cost effective) to use a distribution amplifier rather than a splitter. A splitter effectively cuts the electronic signal in half which can cause all kinds of problems if not compensated for, and even then it really has some other limitations (like cable lengths, etc). A DA electronically duplicates the signal and will (when necessary, like a VGA signal) boost certain points of the signal to keep throughput and signal reference high.

Here's an example of an inexpensive DA that would probably do you well for your application...

http://www.svideo.com/vgamultiplier.html

If you can find a local distributor, and have the money, Extron makes DA's that are generally considered the industry standard:

http://www.extron.com/product/listbytyp ... subtype=32

[lm]

How about replacing your current gpu with one that has two digital outputs and one analog?

[potsy]

Thanks for your replies.

psyopper, your summary is right, I want to duplicate one output to send on a DSub cable to the projector and my card has two DVI outputs. Thanks for the links - the svideo looks like it would do the trick if I go that way.

Im, I assumed that two outputs was generally the limit on graphics cards because that's what you mostly see, so I didn't even look! The good folk at google say there's a few options out there so I think that would be the way to go if I can find one to suit. Thanks for prompting me to start looking!

Cheers
Potsy

[lm]

Im, I assumed that two outputs was generally the limit on graphics cards because that's what you mostly see, so I didn't even look! The good folk at google say there's a few options out there so I think that would be the way to go if I can find one to suit. Thanks for prompting me to start looking!

The ATI RadeonHD 5000 series cards can drive up to 6 displays. While most of them don't have that many connectors, 3 displays should certainly be doable.

[potsy]

Yep, I've been looking at them tonight, and it looks like they at least have two DVI outputs (which have an analogue signal) and one HDMI/display port output. So that would do it. I'm thinking a 5750 or 5670 would be plenty for me.