There are a couple of ways to make RS232 and similar cables, either by soldering or crimping:

1. Soldering is time consuming and can be difficult to do correctly, especially for the novice or those that don’t do it regularly. Moreover, problems with solder contacts sometimes don’t show up until years later, when a weak solder connection fails.
2. Crimping can be much faster, but the quality of the connection is largely dependent on the parts (pins and hoods) used. The type of crimp connector found at radio shack and other electronics outlets are hard to crimp correctly and if there is any strain on the wire, it can easily pull out.

We have found that the best solution is to use crimping, but with a military spec pin and crimper. With this solution, we can make cables quickly and reliably. The pins and tool are not cheap, but neither is a trip back to a job site to troubleshooting a bad wire. In addition, the pins can be easily reconfigured in the event of a mistake or changing of equipment, making the cables more re-useable. The long term payoff is well worth the investment in the upfront cost of materials. Here is what I recommend:

1). Crimper from Ideal (~$120). Here is where I got mine: Techni-Tool.

2). Pins from Stanley Tools. If you find or know of another supplier, please let me know

• The Male pins are part 80-489.
• The Female pins are part 80-480.
• Both can be found here.

3). Stanley also sells the DB-9 backshell, but they are over-priced. I like the ones from Digi-Key:

• The Male backshells are part 1709MA-ND.
• The Female backshells are part 1709FA-ND.
• Both can be ordered here.
• Digi-Key also sells hoods for these backshells.

Below are some photos showing how to use these tools to make a crimp connection.

Note: We learned about this system (these parts) from a client of ours that was in the Air Force and worked on the electrical systems of various aircraft using these crimp tools and techniques.

Short throw projectors have a lot of advantages for most class and conference rooms:

1. The short image throw allows for presenters to approach the screen without interfering with the image or having to look into the projection light.
2. The short image throw also allows for several projectors to be placed in a small room, making it ideal for videoconferencing, or I-TV, classrooms.

However, the installation of these projectors can be complicated. A small change makes a big difference in the projected image with a short-throw projector. We recently learned a few lessons installing a couple of Sanyo PDG-DWL100 projectors in a classroom. The problem was that with the size of the image that we were trying to project, we didn’t have enough height to project on the screen without having to tilt the projector which resulted in a keystoning effect that had to be corrected. However, when corrected, the image size was reduced: so you would have to back the projector farther from the screen, tilt it even more and reduce the image size again. We found that we were simply caught in a situation where we could not ever get the image we wanted without either lowering the screen or getting the projector higher than the current ceiling. You can see the issue with the photo below.

Below is the illustration of the projected image from the manual and you can see that this projector will always take 15% of the overall distance of the image from the screen before the image will start. This is more severe than some other short-throw projectors.

In this case we will build a custom box that will fit into the 2×2 ceiling grid so that we can mount the projector flush with the ceiling grid; a little to the left in the image below. We could attempt to mount the projector flush with the ceiling, but without some room for adjustment, it would be problematic at best.

With 20/20 hindsight, we would have used a smaller screen in this installation (which was the original spec, but we decided to use a larger size since it was being used for the instructor monitor in a videoconferencing classroom). We have at least one more installation of this projector coming up in the next month. In that case, we have plenty of ceiling height to deal with. However, we are going to use a mount from chief that should give us plenty of flexibility and adjustments: click here for details.

Below is a video on the installation of this mount with a short-throw projector.