Details of computer hardware used for the mp3car player/system are described here, along for the reason behind the choices and some of the hurdles that have been encountered along the way (and there were a few!). Also details explaining the mounting and wiring up of the components will be attempted here too. This could get technical - so hold on.

The system is based around a VIA EPIA motherboard and integrated C3 800Mhz processor. The EPIA motherboards are the new Mini-ITX size - measuring only 170mm x 170mm but containing pretty much every input and output desired already on-board, from AGP video with TV-Out through to 10/100 LAN and twin USB ports. VIA has marketed these EPIA setups for a new breed of embedded/low cost computer systems and they have proven to be most popular, especially with the mp3car community.

Whilst the clock speed is equal to the previous Duron processor used the EPIA's overall performance is slightly lower, but still handles the core tasks of mp3 and full screen DivX video playback with ease. The big advantage of the C3 processors are their extreme low power consumption and operating temperature (the C3 800Mhz draws a measly ~5.5 Watts) which is a great advantage on hot summer days in even hotter car interiors! 128MB of PC133 SDRAM provides more than enough headroom for the Windows 98 OS and application software - considering that only 1 task is performed at a time (mp3 or divX playback - no multitasking here!).

Storage is provided by a 40GB 5400rpm Segate IDE hard drive, after my previous IBM 40GB deskstar decided to stop working incar. The drive is installed into a removable hard disc bay and transferred between car/desktop PC for media uploads, scandisks and software updates. I find this system works well compared to using a network card/LAN or other data transfer method due to the high speed of file transfer using direct hard disc copying.

The hard drive bay slots into the front of the case without any extra type of shock absorption method which I have found to be of little use or need anyway. With the unit placed in the car the hard drive is on its side, which in case of a hard shock due to a bump/pothole/other the hard drive heads will not smack into the drive platters which will/may avoid any physical damage to the hard drive. To this day I have never had music skip whilst driving, which could not be said for a lot of commercial car in-dash CD units, nor have I suffered a bad sector on the hard drive.

The custom system case was constructed using 6mm plywood and liquid nails, which gives a light and surprisingly strong enclosure. To give it some looks the case is then covered using grey automotive carpeting as used on the floor of the hatchback, giving some protection from knocks and bumps. The EPIA motherboard is bolted to the floor of the enclosure with the hard disc bay mounted over the top to help keep things compact, whilst the 250W DC-DC ATX power supply as the most bulky/heavy component of the hardware is mounted so its at the base of the enclosure when installed in the car to provide some stability and ensure the system isn't top heavy.

With the major requirements of the system being able to play video/DivX as well as audio/mp3 media the choice of system display is of course critical. In the end a 5.6Inch TFT color composite display with built in tripod was selected, due to its good price, attractive casing and ease of installation into the car without modification. It connects to its video/power cable at the front of the car with a 4pin DIN plug/socket, making it very easy to disconnect and hide the display when parked in a less than secure area. The display can be powered with voltages between 7V-15V, making direct powering from the car battery possible, but to keep the display happy I decided to run it from the ATX PSU regulated 12V supply.

The display requires a composite video input which is supplied through the TV-Out option on the EPIA motherboard. As with my previous Geforce 2 with TV-Out video card I needed to fool the TV-Out into thinking a TV was connected at all times otherwise TV-Out would not be enabled by windows. A 75ohm resistor placed across the composite video output does the work here nicely. Unlike the Geforce 2 card, the EPIA doesn't require a VGA monitor dummy circuit to be present which is nice.

The system is powered via a 250W DC-DC ATX power supply from Zantech here in Australia. By no means the cheapest way to power a PC, with the existing Inverter/ATX supply option winning in this department, but it certainly is more energy efficient and can operate down to voltages of 9VDC. Whilst I can't pick any audible difference between this supply and my existing Inverter/ATX combo, technically the DC-DC supply should provide a smoother supply and thus less noise on the audio output.

Power to the entire system (including amp/pre-amp) is supplied from monster 4GA DC power cable directly from the battery, and grounded back to the car chassis in the boot using another length of 4GA. The system is switched on/off via a 30A horn relay, controlled through a toggle switch next to the drivers seat which in addition controls power to the pre-amp/amp. With this setup I can very quickly cut power to the system as a whole and ensure that no extra drain is present on the battery. The EPIA BIOS has been configured to auto-turnon the system after power failure, which avoids the need to run wires for the motherboards ATX soft-power connector switch.