I built this to help a friend promote her company. Almost immediately after using the Night Billboard, she noticed an increase in business. I am planning on building another one that I will lease out to people wanting to advertise on it. In my town (NYC), even a small ad on a telephone booth can cost $20,000, so I expect that I should be able to make at least a couple grand a month leasing out space on this sign.
In any case, I've tried to be very specific about the parts I used and the necessary modifications. If you build a Night Billboard, feel free to post pictures here ... I'd love to see them!
Step 1: Obtain the Parts
For my overhead projector, I found a 3M 9800 series on eBay for $25 with shipping. I highly recommend this model as it has one of the highest lumen outputs making the image extremely bright. It is also designed to be user-serviceable from top to bottom, so if you ever have any problems, it's relatively easy to make the repairs yourself.
For the light bulbs, I googled around a bit and found the best deal on the EVD - 36V, 400W
here. I don't have any affiliation with this site, but I recommend them for low prices and speedy delivery.
Step 2: Install New Bulbs
You will see the light bulb chamber right in the middle. Lift the lens covering the light bulb chamber and remove whatever bulbs are in there. Remember, to get a bright enough light, we are going to replace the stock bulbs with our new ones.
Carefully insert the new bulbs where the old ones were. Do not touch the bulbs with your bare hands or you will shorten their lifespan. Usually the bulbs will come in some kind of packing material that can be used to help insert the new bulbs without touching them directly.
Close the cover to the bulb chamber, and you're all set.
Step 3: Set Voltage Jumpers
NOTE: if you are using a more modern projector, the voltage settings may be determined automatically and the jumper changes described here will not be necessary.
Locate the jumpers on the circuit board. You can see them highlighted in the image on this page.
The jumpers will be labeled. Put shunts on the STD jumper and the US jumper. If you are not located in the US, use the jumper that is appropriate to your country, but keep the STD jumper shunted.
Step 4: Design Your Graphic
Make the background white, and mock up your text and graphics in black.
When you have everything set the way you want it, invert the colors in the image (Ctrl-I in Photoshop) and you should end up with white text and graphics on a black background. When this is printed, the light will shine through the "white" areas and the black areas will block the light.
Put this file on a CD and take it to your favorite printing shop. Ask them to print it on a transparency. The place where I had mine done charged me around $1 for each transparency.
Step 5: Turn It On!
That's it - you're done! You now have a billboard for far less than anyone else in town paid for theirs.