With a background in electronics and computers, a long time interest in cars and a general case of gadget fever the building of an in-car PC was rather inevitable. The major break-through came when I was pointed to the rather excellent Mini-ITX website and I bought one of their boards. Coupled with the 12 volt ATX power supply from LinITX I essentially had all I needed to construct the backbone of the machine.
I had a 6Gb Samsung IDE hard drive already spare, and a compact IR keyboard and pointer made by Airkey. These completed the machine to a state when I could start installing software and looking at a case for it. To begin I plugged the board and drive into a standard ATX case and used the CD drive in there to install windows 2000 (it would have been Linux, but I need windows for the GPS software I use for in-car navigation). Once that was running and some software installed I looked for the case. I didn't have to look far as the SUN monitor on my Sparc 5 in the workshop was being propped up with an old Sun Hard Disk enclosure which was now empty. At just over 210mm square this was ideal for the 170mm square Mini-ITX board with some room for the hard drive, power supply, extra 12 volt regulation etc.
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It all fitted up quite nice and conveniently, just locating the existing fan to the side of the case and adding a heat-sink on the 12 volt regulator right behind that. All the connectors lined up fairly will with the previous power/scsi connectors, requiring minimal drill/filing to access the others that I needed (LAN, audio, serial, USB).
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The screen in the car is a 5" TFT which I sourced a year or so ago from e-bay in the US, getting a very nice friend to ship it over to the UK for me. It's a colour screen with NTSC input, but the Mini-ITX on-board TV output supports this so it works great. The pics below show the screen mounting in the car, watching a film, using sat-nav software.
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The final picture is of a circuit I found somewhere on the internet and re-designed slightly to use in this application. It uses a dedicated 5A voltage regulator to maintain a stable 12 volt supply even when the car engine is running, when typically the charging voltage when the engine is running will be 13.8 volts or more. I didn't want to risk putting that straight into my newly purchased PSU kit, so I spent a little money on this regulator circuit instead. In use it's excellent and I've not had a hiccup from this kit in about 2 months of fairly serious use now.
Since the first few trials with this I have been looking at other input devices. An Ami Hand Track seems a better mouse input device, and I'm looking at installing a simple keypad for some of the more common functions. Also it doesn't fit under the seat terribly well due to some of the things built into the seat for the belt pre-tensioners etc. I'm looking for a slimmer case now which should allow it to squeeze under those bits and pretty much disappear !
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Wireless LAN is just being assembled for part of the home network now, so obviously the car will be added to this as soon as possible. With this in mind I've added a regulator by-pass into the case so that it can be powered direct from the 12 volt input and hopefully still run when the engine is turned off. Currently the regulator causes enough voltage drop under load that the hard disk will not spin up without the engine running.
All in the new case now ... which fits under the seat much better. My little 'go-anywhere' truck can at least know where it is most of the time now !
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