Vehicle: 1988 Chevy P-30 chassis with Postal truck body
Projection: 1500 lumen Sony 800x600 data projector
Screen size: 72" diagnal, 4:3 ratio
Audio: 40 watts * 2 @ 4ohm, 1000 watts * 1 @ 1ohm (Properly setup)
Main computer: 1ghz AMD running FreeBSD 5.1
Touchscreens: 486-133mhz ScanTouch running NetBSD 2.1
LAN: 10mbps switched
Wifi: 802.11g wireless
Ground Effects: Code L.E.D. full RGB
Power: Inverter, multiple isolated battery banks

I had this project idea for many years, back before there were small portable LCD and DLP projectors availible. Recently after my parents retired out of the area, I lost access to their pickup truck. This made moving large equipment (computer systems) difficult. Some needs cropped up, and I found myself renting trucks from Penske, U-Haul and the like. The prices are pretty steep. The time was right and I started to look at trucks. The P30 postal trucks caught my eye on eBay, this was the truck I wanted. I wanted to purchase the truck before I was to move from Virginia Beach to Norfolk to avoid having to rent a truck yet again, so I was in a bit of a rush. After checking the trucks on eBay and loosing some snipes, I finally found that there was a P30 availible around the corner from my office, waiting for a buyer. Of all the places, the one truck in Virginia was literally less than a mile away. This was good news, as I was originally planning to drive my car with a friend to New Jersey (outside of NYC), pick up a truck and then drive it back to Virginia Beach. The truck was more expensive locally, but I was willing to pay the extra price to avoid the road trip and risk of issues during the trip. I purchased it from Planet Auto, and have absolutely no complaints!! I told them that I planned to cut the side out and put in a rear projection video display, and they thought it was an excellent idea.

Everything in the truck is setup to be removable. This is for both security, and so I can use the truck to move larger equipment. Due to budget constraits (I didn't have a ton of cash) pretty much everything is from eBay and used sources. Without these resources, I wouldn't have been able to put it together. Don't get me wrong, eBay is dangerous if you don't know the game -- and as a company they are evil. But there are savings to be had if you know what you are doing.

After using the truck to move, I started to make my moves on it. I added some audio components, and started experimenting with power conversion. At first I tried using APC and Exide computer UPS units to convert the 12vdc to 120vac. (Thanks to Henry Griggs and Jim Conrad for the UPS parts!). At this point in time I was using an older projector that used a halogen lamp, and the UPSes weren't capable of handling the power requirements. The APC units were too smart, and wouldn't power on without them being fed AC power first. The Exides were better suited, and had no issues other than being overloaded. Once I realized the small UPSes wouldn't do it, I started looking at larger inverter/chargers used in RV and houseboats. I couldn't move to larger computer UPSes as they start to use 24vdc and 48vdc input, utilizing multiple 6 and 12 volt batteries in series. I picked up a cheap 2200 watt inverter/charger from eBay, and it is in use now.

In time I added 3 size 24 deep cycle batteries. I've had lots of problems with charging, as trying to charge a dead battery bank results in a dead charger. I've killed 2 Schumaker digital chargers, and the charger built into the inverter. I will have to move to a marine charger.

The audio is handeled by two Pioneer 3-way 6x9's (cheap $60 ones), and 6x9 boxes. These are setup to be removed, as Hampton Roads scum have already stolen one pair (smashing a hard to find window and causing me much headache in the process). The 6x9's are fed by an old Sony 4 channel, 40 watt 4 ohm car stereo amplifier. This amp is from my high school days (1994?), but still performs flawlessly. The low end is handled by a car speaker box I found on Craigslist, which is driven by a craigslist purchased Kenwood amplifier delivering 1000 watts @ 1ohm. This has caused some electrical issues, and being a big truck the bass isn't nearly as tight as smaller vehicles with smaller subwoofer setups.

Similiar to the 6x9 speakers, the large speaker box is easy to remove and relocate when the truck is not in use. An MTX crossover given to me by my friend Erik seperates the highs from the lows. None of the audio equipment is great, most of it probably hasn't been on the market in 6 years, but it's properly setup so it rocks out unlike most of the loud cars you hear on the streets of Hampton Roads. And yes, it can thump, and that makes people laugh because it is an old postal truck.

The video is driven by a computer projector, of midrange light output and a resolution considered low by todays HDTV standards. The low resolution is fine for the truck, the light output being the most important aspect. The projector is fed from a desktop computer, described below. I do believe the vibration has caused the LCD panels in the projector to come slightly out of convergence, but as long as the bulb stays bright and she doesn't die I'm okay with this.

A 1GHZ desktop PC serves as the video playback system as well as content storage and a network server for the truck. Three touchscreens in the front of the truck run NetBSD, and are simply terminals running an X server. Web browsers are sent to the touchscreens from the 1GHZ PC, which are pointed to web pages on the local system. The web pages allow quick selection of video or audio, as well as messages and volume control. I haven't had a chance yet to tie the ground effects into it -- but it is part of the plan. A wireless access point has access to a 2nd network on the truck which is more secure than the one used for the touchscreens. This allows streaming of video to the truck from a notebook PC from inside of a venue, as well as allows me to use a PDA to control playback. There are some flaws, and I generally don't like web applications in this type of setup. However, it does the job, and is flexible with allowing PDAs to control things.

I originally set out to build my own LED based ground effects using 5000mcd red, blue and green LEDs from China. I hacked up a single "7 color" ground effect bar from a different kit and was able to get lots of colors out of it using pulse width modulation, some chips and a PC running Linux. The problem was it was so labor intensive, and with the truck coming together I wanted it on the road. I did some looking around, and purchased a bunch of sample parts from a Chinese company called Code L.E.D. (before you hate, America doesn't make anything anymore). My goal is to run the tubes without their controller, but at this point in time I'm using their controller until I have more time to check into timing issues. I was able to get a PC running Linux to trigger their multi-color tubes, but not reliably because the PC isn't running a RTOS and the timing I'm using isn't accurate enough as the communications are straight up serial blast with no clock signal.

I went a larger name car audio place to check out the prices on wire, and it was thru the roof. I won't ever do business with Discount Auto Sound after an event a few years ago where they sold me the wrong item and wouldn't take it back, so I was thinking I would have to mail order the wire I needed. Then I found Ocean Audio down near the oceanfront, and decided to check them before I went home. I remembered the name as they sponsored some sort of local car audio show some time ago. I rolled down there as a last ditch effort to see what they had in terms of wire and accessories, and I was surprised. Good stuff, nice people, good prices. I bought a ton of wire from them, and plan to clean up the install in the truck. I give them a thumbs up. Go there before you go home dissapointed.

While the truck is neat, it's is one of a million project ideas. The main limit is money, followed by time. I've already got other things brewing up. Bigger and better, sure to get their very own website. Stay tuned! -- Ethan