CarPC

 

Processing and Amplification

Now the work has been done to build to a nice machine to serve up a vast collection of music at my whim, it didn't make much sense to do things half assed; au contraire - I prefer to do things whole assed!

 

I still had some bits and pieces lying around from when I used to take car audio way too seriously, including:

  • Audio Control 2XS Series 2: 2 way active adjustable crossover;
  • Soundstream Reference 404s: 4 x 50WRMS power amplifier;
  • Phoenix Gold 4AWG fuse holder, and big fat cables for power, such as that stupidly large red 4AWG power cable in the photo on the right. What is impressive though is that the Soundstream has power connectors big enough to take this cable, and power traces inside that don't make you feel like blushing when you hook it up;
  • Speaker cabling and interconnects by Streetwires and Stinger.

First trick was to mount the goodies somewhere out of the way. This little cubby near the rear of the car did the trick nicely. The aluminium frame had the crossover bolted to the rear, and was then fixed in place in the car, and then had the amplifier bolted in place in front of that.

 

Setting the levels on the crossover is a pain in the ass, as removing the amplifier is a half hour job :-(

Power for the amp comes directly from the battery (via the fuse, all as per IASCA regulations :-) ), while the earth strap grounds every component in the audio chain about 12 inches from the amplifier.

Power for Otto is pulled from the amplifier as well - you can see the orange wire peeking out from behind the power feed cable.

 

The remote turn on for the amplifier is driven by the computer power supply - when the computer is on, then the amp comes on as well, which is handy if the car is being dropped off for servicing, as I can kill the entire system.

 

Audio Control 2xs crossover installed

 

Cables run from the battery and to the speakers

 

The amp and crossover cradle - almost ready

 

The Screen

Below are shots of the DSCustoms 5.6" screen mounted in the dash. Photos of the screen in action can be seen on the software page.

 

With the screen stashed away, it's suitably stealthy. The slot below the screen is currently home to the IR receiver, however a UHF CB radio is planned for installation in that slot.

 

As with the motherboard, I bought and sold a couple of different screens before settling on the one that I'll use in the car.

 

Generally, the cheapest entry into the colour LCD screen market is the 5.6" LCD monitor, and this is usually supplied a signal via a TV-out connection. TV-out is fantastic for TV, but only pretty average when it comes to computer displays, however the screen that I sourced from DSCustoms (Dave - I'd link to your site if you had some content!) in the USA had the added advantage that it can be hidden away in the dash when not in use. It's a similar concept to that employed by Alpine and Kenwood, however this one isn't motorised, which helps keep the costs down.

 

End game solution (I've started planning Mk II already :-) ) is to use the same mounting technique to support a VGA 7" wide screen with touch screen. There is a project of this nature already underway on mp3car.com, which I'm watching with interest :-)

 

[More images available]

The Computer

Here you can see the case for the computer installed under the drivers seat. The white USB cable (seen disconnected next to the computer case) connects to the 4 port hub in the armrest console. The black wire is for the Deluo GPS - I've only just started playing with this, and I haven't figured out where it will be finally installed.

 

On the right you can see the USB hub, and the Fellowes touchpad, which is used for controlling the computer for adjusting EQ's, playing with plug-in's, and messing with config files. I'm scoping out mini keyboards at the moment - that on-screen keybard is hella-hard to use! The USB hub is handy for plugging in the digital camera to download photo's, or to connect the USB 2.5" drive I use to transfer data / new music between the house and the car.

Armrest console contents

<Homer>

Seat roll forward ...

... Seat roll back

</Homer>

The Motherboard

The project originally began life with me picking up an MSI micro-ATX motherboard (MSI 6154). It had on board sound, and was a Socket 370 board which suited my preferred processor, but then I found the VIA. The MSI board quickly got put on the shelf (in readiness for the Home Theatre PC project, which will be powered by a VIA C3 1Ghz processor; but I digress...).

 

Really, a VIA EPIA board with a 800Mhz embedded processor, and onboard video, tv-out, sound and networking - what else could I want? All it needs is a power supply, memory and RAM...

The Power Supply

Setting up a computer in a 12VDC environment is a challenge, especially when you don't know a diode from a transistor (which I thought was some type of radio - anyhoo)...

 

A number of options exist in areas of both build and buy, and my selection was ultimately made based on the fact that PC Power and Cooling are a nice big company that offer luxuries like warranties. The fact that they don't have an Australian distributorwas not a problem, and that I dealt with their helpful, friendly international sales staff. This landed me a well packed and documented 12v DC-DC power supply.

 

There are smaller power supplies on the market, but given the planned enclosure design, the 30mm difference in length between the motherboard and the power supply is a non-issue.

 

Other Hardware

A number of other bits and pieces have been sourced to do all the things that I currently have planned for the system, including:

 

The Deluo USB connected GPS. NMEA compliant output, and a bit of a bargain.

The D-Link USB connected FM Tuner.

 

Found by a friend by complete chance in a dump-out bin at Harvey Norman for AUD$19.95. If you were of a mind, the board inside this oddly shaped enclosure could be removed and mounted in the computer case. This may still be the result, however I'm a little concerned about space, and I need to figure out what, if any, the interference factor will be like under the motherboard and next to the power supply.

The Pocket Boy Slut Drive

 

I have no idea whether these guys have a site and it's hardly important enough to link - it's a USB 1.1 enclosure for a 2.5" IBM laptop drive, and is used to transfer data from the home network to the computer in the car.

Nice little keyboard. Has a bunch of excess button along the top, and two USB ports on the bottom. A nice little pickup from ebay.

Proper hardware

Naturally, when undertaking a project such as this, there is a need buy more tools. Well, that's the excuse that I used :-)

 

If you're as nervous about on perspex as I was, this is pretty much everything that I used to build my enclosure. In short, everything is hand tools, and I did all the work on the floor of my lounge room.

If you're planning on doing this - some helpful notes:

  • Acrylic, when sanded, dremeled or filed, is noisy
  • Acrylic, when sanded, dremeled or filed, is smelly
  • Remember to use your dremel only in the commercial breaks
  • If you buy a dremel, and the little book recommends speeds for cutting different materials, believe them. They don't do that just to fill up the pages.
  • After the dremel and the sandpaper, pull out the Brasso and a rag, and polish endlessly. You'll know when to stop.

Because I'm lazy, and there is a Bunnings hardware store at the end of my street, I bought all my bits and pieces from Bunnings. Don't mention that you're building a computer for your car. They will think you are strange.

Different blades are available for Stanley knives. The odd looking one is a scoring blade, and is perfect for cutting acrylic/perspex. Use a straight edge and run the scoring blade lightly for the first few passes, and from there keep digging with the blade. You'll quickly get the feel for how far to go.

I wouldn't recommend this method for anything more than the 3mm acrylic that I used, unless you were planning on watching every episode of The Godfather and The Soprano's and had an endless supply of blades :-)

The Paint/Adhesive guy at Bunnings was really helpful.

 

Initially I was looking for the solvent stuff that everyone seems to rave about when building in acrylic. Bunnings don't stock this. As I was planning on using Aliminium to strengthen and finish the edges, I didn't really have to rely on the glue by itself, and this stuff sticks anything to anything. I'm glad we don't have a cat.

The Literature for Weldbond doesn't mention plastic/acrylic at all, but I had G clamps and time to let it bond.

 

If you're planning a acrylic only box, maybe this isn't the stuff for you.

 

This just in: Weldbond was voted 'Glue of the Month' for the second time by thistothat.com.

 

Wow.

 

I'm too embarassed to include a picture of the mighty Ozito dremel - it's a copycat! However it does the job. All the attachments that can be connected to the original dremel also fit mine, which gives me the best of both worlds, as I don't use it often enough to justify professional grade toys ^H^H tools.

 

 

I bought the mini file set from Jaycar (I know - it's not Bunnings, but Jaycar is just down the road from my work). At AUD$14.95 it was one of the best investments, as they are sharp and bitey, and excellent for that fine detail and slightly widening holes to fit standard computer sized screws - be they in circuit boards (like the USB radio) or in the acrylic to take brass motherboard stand-offs.

 

 

Just to make sure that this site doens't get picked up by AOL, I'll use the proper name for the file on the right - it's a medium coarse half round bastard file. Attack with this, then the mini files, and then a sanding block for quickly and neatly finishing edges.

Software

The software shown here was not written by me - I simply passed on what I wanted the software to do, and how it would do it, and hey presto, it happened. The entire application is controlled by an IR remote control, which performs all the obvious functions for Winamp and radio playback, in addition to flipping to the screens created for the GPS.

Changes that were made to the software to justify the "Custom Written" tag dealt mainly with the manner in which different functions behaved, and the addition of support for the USB radio. We're all different, and just these simple changes took the best part of a day.

 

I got about a billion ideas for further development... watch this space!

 

Screenshots

It's hard to take photo's at 100 km/h!

Music mode displays the ID3 tags for the Artist and Title, followed by the elapsed and total time. Controls issued by the remote control are sent to Winamp (still v2.81 - stable!). The line of text across the bottom of the screen displays the time, the name of the suburb I'm in and the post code, and then the current speed and heading. Eagle eyed viewers will notice the line of yellow text below the name of the track - this is the debug codes for programming the IR remote control.

 

The Radio mode is exactly the same in appearance as the Winamp screen, except in this case it sends commands to Radiator which is running in the background and controls the DLink USB radio card.

The Speed/Trip Meter is pretty self explanatory. The histogram at the bottom of the screen logs speed via the GPS - the three horizontal lines indicate 60, 80 and 100 km/h. Makes it pretty easy to spot time wasted sitting at traffic lights. It was interesting to note that with my slightly oversize BF Goodrich All-Terrains my speedo is pretty much accurate, having consumed that little safety margin that our friends at Isuzu give us.

 

The GPS Mode screen is interesting for a couple of reasons. Firstly, this is what the screen looks like after taking off the protective plastic, but prior to cleaning the screen. Secondly, the screen is in direct sunlight, and is more than bright enough. As street level navigation is not available in Australia, I'm running OziExplorer, with various maps which we've scanned. This screen still looks a little manky, as it's designed for a 7" screen, rather than this 5.6".

 

Music Mode

An overview shot of the screen in
action - here in GPS mode

Speed/Trip Meter

GPS Mode

 

Building the Enclosure

I was pretty nervous about taking this on myself. I toyed with the idea of chopping down an AT style tower case (which are typically 180mm wide - perfect for an EPIA), and also with buying a case. However, being a bit of a perfectionist, the AT didn't suit as I didn't have the equipment to work with steel, and buying a case wouldn't get me what I actually want.

 

I went with acrylic because it's easy to work with, and they sell it at Bunnings. Although it's satisfying seeing the job finished, I think I'd get someone to either cut or bend to my specification next time, as I don't have the skills to satisfy the quality of work that I would have liked to achieve.

 

After scoring and cutting the original sheet, duct tape was used to hold the parts together to test the parts for size. The box is actually 60mm longer here, as a result of some issues with a decimal place. The pieces were then cut back, arriving at a final planned size of 205mm x 220mm x 95mm.

The acrylic looks a little cloudy here. This is because the protective plastic is still attached to the sheet. Other sites mention a preference for acrylic that is protected by adhesive paper rather than plastic. Having now worked with both, I can only agree. The plastic stuff is annoying, and the quality of protection is crap near any edges.

File is on hand to make 'adjustments'.

All external edges are protected by aluminium angle. Aluminium is so easy to work with, and the only other addition to my tool kit was a mitre box so that I could make pairs of 45 degree cuts so as to bend the length as shown.

Lots of things here.

 

Those corners for the cut-out for the power supply were annoying, and were the final straw which had me wandering down the street to Bunnings to pick up a dremel, so that I could cut the edges rather than having to rely on snapping the material following scoring. Radius-ing the corners when the job is done is clever, as this will help to avoid cracking in the future.

 

Next to the power supply is a 2.5" laptop drive.

Attached with tape to the inner sides of the enclosure are the two rails that will support the motherboard.

As above, reverse angle.

And here we have the shelf for the motherboard, cut from acrylic, sitting on the shelf supports, with the motherboard in place.

 

There are gaps at either end of the enclosure - 20mm at the far end to allow power supply and IDE cables to connect to the motherboard, and a larger gap at the nearer end to give USB cables etc turning room to be connected.

Bottom right shows the profile of the aluminium angle poking through the cut-out for the power supply. This was used for the lower frame and the corners. For the top frame, a profile that was slightly longer on one side (1.6mm vs 1.2mm) so as to give more surface area for the glue to bond.

The round hole on the left is to feed all the cables through to connect to the motherboard etc. I orignally planned to use the template supplied with the motherboard, but I found it too tall.

In this shot, the motherboard support shelf has been taped to the aluminium brackets using double sided tape. I have no doubt whatsoever about the strength of this stuff. It would be easier to make a new shelf than try and disassemble this one.

 

The brackets have been drilled while taped to the sides of the enclosure, and short 3mm nuts and bolts (from Jaycar) hold the shelf secure.

 

This is actually night two of the gluing, and the ends are being glued in place. The sides were glued in on the following night.

 

You may notice that the acrylic seems surprising clear now. It's so much nicer to look at without the protective plastic. Clamps are essential to the build. You can't have too many of them.

And here we are with all the sides glued in and the shelf mounted. Careful viewers will notice the brass standoff's mounted on the motherboard shelf. These needed to be filed down so the thread did not protrude through the shelf and foul on the power supply.

 

For extra protection, a neoprene mouse mat was cut down to shape to fill out the space between the shelf and the motherboard. I doubt that flexing would have been an issue on such a small motherboard, but better to be safe than sorry.

As above, this time with motherboard mounted. Now it's starting to look like a computer!

Big gap here.

 

It's finished. As mentioned above, a different profile was used for the top, so that the lid could slide in and out.

 

Aluminium added to each vertical edge to improve strength, as I managed to weaken or break some of the glue bonds by carrying the case around the house in a cavalier fashion.

As above, but with the slidey lid half slid. I hope it doesn't rattle. [Edit: It doesn't.]

Lid open, RAM installed, machine has been booted, configured, and is operational.

 

Next step is the installation in the car - planned for November.

 

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Last updated: 2009-10-29

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