One PC - Two Projectors 1

[OsakaWebbie]

I'm preparing to be in charge of projection (Powerpoint, video) for a conference, and I won't know ahead of time exactly what projectors I will have access to (some participants are volunteering to bring their own). But one thing I know is that the main room will be served better by two projectors rather than one - I have never done that before, so I'm trying to learn what is needed.

Most projectors have an RGB output as well as input, and I thought, "well, all I need is a cable long enough to go between the two projectors." But I peeked at the PDF manual of a randomly selected portable projector, and it said the output was only for an external monitor and that daisy-chaining projectors is not possible. Huh? I don't know how the projector could know that it's being connected to another projector rather than a monitor.

Anyway, who out there has done this, and do I really need some special splitter box, or is there an easier way?

 

[vanka25]

If the output is going to be VGA, then you can get a VGA splitter cable for about $10.

 

[OsakaWebbie]

So what you're saying is that indeed the VGA output on projectors cannot be used to drive a second projector? For me, the spitter idea has two concerns: (a) The PC's signal strength would be split between the two, and in this case one of them would be a fairly long cable run (about 15-20 meters maybe), and (b) it would be a one-use purchase, and here in Japan I suspect the splitter cable is more like $40-50. So I wanted to make sure I understood the situation and had exhausted other options before looking that route, because I suspect it would not only be a splitter but also some sort of amplifier or something (and I won't have any opportunity to test the setup before leaving home, and once I get there, electronics shopping may be difficult - the conference is in Thailand, and I don't speak Thai).

Is no one doing this? I expected more responses, as my impression is that most modern churches and conferences larger than about 300 people probably do this all the time. Am I wrong?

 

[vanka25]

In response to your first question: No it's not possible to daisy-chain projectors. Each projector must be directly connected to the output.

Recently my church installed three projectors and we have a video splitter/amplifier that was in the $200-$500 (US) range. I am not sure of the model as I wasn't intimately involved in the install. I'm not sure that this is the solution you were looking for. If you have a contact there, would it be possible for them to check around to see if something is available to rent?

The splitter that I was talking about was just a Y-cable, I don't think it would be too much more in Japan or Thailand; but if the cable runs are going to be in the 15-20 meter area, you will probably need an amplifier. Another option to look into is to send the video signal over CAT5 cable; google "vga to cat5" or "vga over cat5" for products and instructions on how to accomplish this. I recall reading a online tutorial on how to splice your own cat5/vga cable.

 

[OsakaWebbie]

Thanks for the clear answers. In the end we decided that it wasn't worth the hassle and expense for one conference, so we'll just use one projector and let the people on the far side crane their necks and test their eyesight. But this was useful information for the future - I expect that I will run into this issue again, and then it might be worth doing something more sophisticated.

As for how a projector can tell whether it is connected to a computer's VGA output or another projector's VGA output, I'll just add that to the long list of things I don't know and don't really need to know...

 

[vanka25]

Projectors don't usually have VGA outputs, they have VGA inputs. So a projector can't tell what it's connected to as long as what it's connected to outputs a signal.