VGA to Composite Converter

I would like to convert a VGA signal to a composite signal to send through the buildings' video cabling. I see converters out there from $1 to $100. I assume there's a difference -- can anyone give me any advice on this? I can't imagine that you could simply connect 5 VGA wires to a single wire.

I'd suggest bugging FM for a AVDH-2.

(Or maybe a -1 if your site might be originating a broadcast.)

There might be better and cheaper, but it would keep things standardized as well as eliminating the need to rewire a rack everytime you want to change modes.

If you want to keep it cheap, I've had pretty good results from this $30 Sewell Direct SW-23000 converter found on Amazon.

Thanks very much. We were thinking on the cheap end, so I'll look at that Sewell unit. But I didn't know about those AVDH units. I didn't realize they have everything necessary to hook up a remote camera, including the serial to network cable converter. Very pricey though.

craiggsmith wrote:Very pricey though.

Yes, doing things "right" is rarely cheap. In this case, the stake president might be able to persuade FM to get it. (The church price might be less.) Particularly if they have any extra funds at the end of the year.

Thanks, I'll look at that option.

But it just doesn't seem like it offers much for the cost. I think there are cheaper "right" ways to do it, but I'll have to do more research.

"Right" way is subjective. When dealing with a large operation, a standardized way is always good. Particularly as people go on vacation, move out of the stake, or change callings. The AVHD is standardized and can be supported by both CHQ and the forum. Other options - not quite so well. Switches eliminate the need to re-cabling when switching between different modes of operation.

I apologize that I didn't clearly explain what I was trying to do or what we already have. We have a source switcher in our rack, and I was looking for a converter to put on the rostrum, not at the rack.

This actually would require re-cabling though, as the jack on the rostrum is an output, not an input. But I don't see any way around it, unless we can re-purpose the RF cable. We don't use it, but I'm told those outputs are daisy-chained, so not sure if it's possible.

craiggsmith wrote:This actually would require re-cabling though, as the jack on the rostrum is an output, not an input. But I don't see any way around it, unless we can re-purpose the RF cable. We don't use it, but I'm told those outputs are daisy-chained, so not sure if it's possible.

Yes, RF cable can be run differently and it may prevent you from repurposing it. You'd have to make sure the run from the cabinet to the podium is only for the podium and nothing else.

craiggsmith wrote:This actually would require re-cabling though, as the jack on the rostrum is an output, not an input. But I don't see any way around it, unless we can re-purpose the RF cable. We don't use it, but I'm told those outputs are daisy-chained, so not sure if it's possible.

Just to be clear, are you talking about possibly repurposing an RF cable that has an F connector, or is it a composite video cable with an RCA jack? If it's the latter, I wouldn't permanently repurpose it, as it's great to connect your satellite system to a projector for conferences and other broadcasts.

If you have an RCA wall jack in the chapel overflow area, THAT will be your composite video input point. If you only need this setup on rare occasions, you could get a long RG-59 cable and temporarily run it along the chapel wall to the overflow area. At Monoprice, $20 (plus shipping) gets you 100' of twin RG-59 coax with RCA plugs that can be pulled apart to make TWO 100' runs.

If the only reason to run the cable is for a overflow projector, and you're running a cable though the chapel, consider using something other than composite. If you're feeding a webcast or other rooms, then you may have to make a sacrifice in quality to get the signal from point A to point B.

We have two jacks at the podium, one is RCA composite video that we use to show satellite broadcasts, and the other is F connector RF video and we haven't used it in years. We do have a jack in the overflow that we use for the camera input for webcasts, but we want an input at the podium. We would probably use it often enough and I'd really like to avoid running temporary cable, especially across traffic areas and especially coax that doesn't want to lay flat. We would use it mainly for the overflow projector but also occasionally for webcasts. I just haven't found any other good options.

I will try to get up there this weekend and see if I can determine if it's a direct connection or not. Not sure if it's really possible to tell though.

Before you decide to use it, first check to see what kind of cable it is. Unscrew the wall plate with the F-connector and pull enough coax out to see the markings on the jacket. If it says RG-59, RG-59/U, or something similar, it will support composite video. If it says RG-6, RG-6/U, etc., you probably don't want to use it for that application.

The reason gets a bit technical, but basically, RG-59 has a solid copper center conductor, with a pure copper ground braid; while RG-6 is made with a copper-clad steel wire, with an aluminum foil & braid shield. Because RF frequencies travel more along the "skin" of both the center conductor and ground braid, it doesn't mind that below the copper clad of RG-6 is a rather poorly conducting steel wire. Composite (or baseband) video is much lower in frequency and travels more through the core of the wire and DOES mind having to plow through steel. For short runs, it probably wouldn't matter, but if you are taking it any distance the loss will eat up much your composite signal before it reaches the other end.

Just a head's up before you put too much time and effort into it.

Thanks for all the info. Once upon I time I knew all the technical details behind this stuff, but it's been a long time and I've forgotten most of it. Usually my curiosity drives me to research things, but I haven't gotten around to it, so this was a good impetus to do so.

I didn't know that any wire would be made from steel; I would have assumed aluminum if not copper. I also didn't know how bad of a conductor steel was. I haven't had a chance to get over to the church to check the wiring. I trust that what you're saying is the norm, although my research tells me that the RG numbers don't really mean anything except essentially size and impedance, and that any cable could have any type of conductor and shield. I'm curious what our existing cables are for the composite jacks.

How long can you run standard composite video cable? I assume some are better than others. I hate dealing with stiff coax.

Back to the earlier comment of just needing to run a signal to the cultural hall -- this is usually the situation. I would prefer not to degrade the signal, but if I remember it didn't seem like there were any easy options; I think I would have to balance an analog signal. I guess HDMI can be run longer with good quality cable, but there doesn't seem to be any official specs over 45 ft. At any rate I don't like running cable across traffic areas when possible either, but getting our building retrofitted is not likely to happen for a long time.

But in a couple weeks for some reason our stake is hosting the Church and Scouting conference, which will require presentations to be sent via webcast to another building, so I figured I'd pursue the composite signal option first. Not sure why we are doing this; it seems they could find a better place to hold it. If any of you are attending you're welcome to help!

But we do have some funds to buy something now, so any suggestions would be welcome.

To add to the fun, composite is not designed to be sent long distances. The amplitude of the signal is fixed by spec. Some devices deal with a weak signal better than others. Some have noticed problems trying to feed video mixers with less than optimum signals.

I have a cheap video distribution amplifier I got at radio shack -- but it's so lightweight I question what it actually does. If the amplitude is fixed I guess it just allows you to split the signal without as much degradation as opposed to amplifying a single signal. It would be interesting to measure it.

craiggsmith wrote:I have a cheap video distribution amplifier I got at radio shack -- but it's so lightweight I question what it actually does. If the amplitude is fixed I guess it just allows you to split the signal without as much degradation as opposed to amplifying a single signal.

Quite likely a unity gain amplifier with multiple outputs. It's job is distributing the signal rather than boosting it.

craiggsmith wrote:It would be interesting to measure it.

More than you probably wanted to know: Measuring composite-video signal

Note that video signals use the "IRE" unit instead of DC voltages to describe levels and amplitudes. Based on a standard 1 Vpp NTSC composite-video signal that swings from -286 mV (sync tip) to +714 mV (peak video)...

You'd need a scope of some kind. The fact that it's a non-sinusoidal signal and frequency of several MHz I think rules out DVMs for making the measurement.

It certainly seems possible to measure the sync pulse and adjust the signal so it's the correct amplitude. But I'm not sure just where you'd find such equipment.

Used to have a scope ...

So I checked out the cables at our stake center - of my cable stash, all are RG-6 except one, the RG-59 cable I used to use before they installed composite video. I did like the flexibility of that one a lot more. However, that RG-59 is a copper-clad conductor, not solid copper. Of the RG-6 cables, some are solid copper and some copper-glad. I did confirm that the RF output on the rostrum is a direct feed from the cabinet, and although it's RG-6 it's solid copper as well; it's the same as the composite cables.

If your RG-59 is CCA (Copper-Clad Aluminum), it should work OK. CCA is only slightly more lossy than pure copper. The way to tell if your center conductor (or braid for that matter) is CCA rather than CCS (Copper-Clad Steel) is hold a magnet to it. If it has attraction, it's CCS. Yes, I've seen solid copper for RG-6, but it's not very common.

Sounds like you've got a few options to explore!

I'll try that, thanks. One of the conductors bent very easily so I'm thinking aluminum; others are very stiff so might be steel.

Is it OK to run a regular RCA cable from the camera or projector in the middle to the jack on the side (~30 ft?), or should I run coax for that distance?

craiggsmith wrote:Is it OK to run a regular RCA cable from the camera or projector in the middle to the jack on the side (~30 ft?), or should I run coax for that distance?

I'm not sure what you mean by "regular RCA cable". I think you'll find most cable with RCA connectors is coax of some kind, with some being quite a bit thinner than others. The thinner it is, the more loss per linear foot it will have, so I wouldn't recommend anything smaller than RG-59, unless it's like a patch cable that's only a few feet long.

In my limited experience I've found the term "coax" to refer to an RG-6/59 style cable with an insulator/dielectric of a specified size between the conductor and shield (of course coaxial) to create particular electromagnetic properties, usually with F-connectors.

I'm referring to the basic cables with RCA connectors you can buy at a regular store, which do not have any particular specifications regarding construction or electromagnetic properties. With the cheap short ones (often called patch cables) the video and audio cables appear identical, but there are longer and thicker ones that I assume do have a coaxial shield, but I've never heard them referred to as coax. I have several in the 10 to 15 feet range that I have used with no noticeable signal degradation, and even strung a couple together on occasion as well. But not sure what the typical accepted maximum run is for them. RG cable is just a pain to work when laying out temporary runs.

I went ahead and got a converter directly from Sewell, http://sewelldirect.com/pc-to-tv-adapter.asp. Sewell is located in Utah (so one day shipping to my location, or I can drive down and pick it up), has same day shipping, an excellent return policy, and real tech support people readily available. Happy to have discovered them, thanks. I will be working with them on an HDMI solution for within the building and post if I do something.

I do with there were a Fry's here in Utah though.

Should this topic have gone under Broadcasts and Conferences? Feel free to move it if so.

Got the converter and tried it out. The quality is poorer than expected but probably normal for what it is. It's no better than just filming the screen with the camera (EVI-D70). The biggest problem was the aspect ratio; even with a 4:3 input I had to set the projector to 16:9 for it to display properly. So switching between it and the camera wasn't convenient.

craiggsmith wrote:The quality is poorer than expected but probably normal for what it is.

Back in the day, composite wasn't good enough for a 80 character screen. You had to use something like a Hercules monochrome or CGA to get 80 column text. Today, we cringe at 80 column screens.

craiggsmith wrote:The biggest problem was the aspect ratio; even with a 4:3 input I had to set the projector to 16:9 for it to display properly.

That's interesting. Was the computer also connected to a 16:9 display so the computer output was 4:3 displayed on a 16:9 screen rather than a true 4:3? If so, then perhaps a different computer or video driver can change that. Or perhaps set the VGA output as a second monitor - that should allow you to set it to a different resolution. The laptop screen is the "control' for the slide show.

russellhltn wrote:

craiggsmith wrote:The biggest problem was the aspect ratio; even with a 4:3 input I had to set the projector to 16:9 for it to display properly.

That's interesting. Was the computer also connected to a 16:9 display so the computer output was 4:3 displayed on a 16:9 screen rather than a true 4:3? If so, then perhaps a different computer or video driver can change that. Or perhaps set the VGA output as a second monitor - that should allow you to set it to a different resolution. The laptop screen is the "control' for the slide show.

I set the laptop to 1024x768, 4:3. It was only connected to the projector, although I think the monitor output of the projector is just a pass through. When we connected the composite output directly to a TV the aspect ratio was fine; it was only when we sent it through house video distribution system to the other projector that it was a problem. But I'll do some more testing.

craiggsmith wrote:I set the laptop to 1024x768, 4:3.

And of course, the laptop is connected to it's own screen.

craiggsmith wrote:When we connected the composite output directly to a TV the aspect ratio was fine; it was only when we sent it through house video distribution system to the other projector that it was a problem.

That's puzzling. I'd wonder if the first time the laptop screen was turned off and the second time it was turned on. That can make a difference. If it's driving two different screens, it has to compromise.

Did more testing today ... and am now more confused than ever. I've used multiple monitors and projectors for many years but have never had so many problems getting something to cooperate.

One thing I discovered is each device is different. I tested 2 projectors and two TVs. The old projector we used to use displayed it fine. And the two TVs each handled the signal differently.

When I changed the laptop to dual-monitor mode I could get the display correct on the original projector. But once I did that I couldn't get the thing back to single monitor mode for further testing. I would turn it off in the display properties but then it would turn off the external monitor. When I re-enabled the external monitor but it would turn on extend mode again. And it kept changing the resolution. After a while my head started spinning so I came home.

I didn't test the configuration today that I had last week, with it connected to the projector first and then to a TV through the pass-through. So I'll go back up and test again. Given that most people want to see the presentation on the laptop screen, and that VGA is dying, I'm not sure it's worth pursuing, but I'll start another thread about that.