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Ask Slashdot: How do you build a PC for the car? 141

Posted by Cliff from the things-to-know dept.
Bruce Linley sent in this rather interesting question: "Whether it's an MP3 player or a GPS navigation system, what hardware is best suited for use in an automobile based PC? Hard drives must be tolerant of excessive vibration; the CPU must operate locked in a trunk where temperatures can reach 100C or -50C and where there is poor ventilation. The 12V power in the car may be somewhat dirty and variable. I/O cables may be subject to noise in long runs...and so on. Help me pick the components for the most rugged and reliable automotive PC!" Man! I would love to do something like this also! Comments, folks?
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Ask Slashdot: How do you build a PC for the car? More

Ask Slashdot: How do you build a PC for the car?

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  • I use an old 386 "noname" laptop I scored for $100 about 3 years ago. I run DOS and New Deal Office on it. (With only a 40 MB HD, I don't think it'd handle Linux and a Linux WP program.) It's never been a problem. One day I might get a newer "car computer," but it'll just be another laptop. Why take up trunk space?


    --Robin Miller
  • You just need to find a company that sells robust CD-ROM drives. Car audio CD changers work perfectly fine with vibrations, hot, and cold, so I don't see why CD-ROM drives shouldn't work similarly.
  • Yes, but an mp3 player can actually work with LESS throughput than an audio cd player, since the music is compressed. A single-speed CD-ROM drive would do fine.
  • One thing you might try to use for CPU cooling: a Peltier cooling unit. I bought one from ComputerNerd [computernerd.com] a while back. I haven't had a chance to install it yet, but it certainly looks impressive. :)

    It looks as if they might not be carrying this model any more, though - the only Peltier units I see on their Web site are for older Socket 7 Pentiums, not Pentium IIs. (The model I have is a PAP2X3B.)

    I've heard that Peltier units can get cold enough to actually freeze water, which is a problem. If the system is running in too hot an environment, it may cause condensation, which is definitely not a good thing.

  • Posted by Phantom of the Operating System:

    just get a reliable CD Rom (or an array of them) in addition to the flash. Just put a limited amount of data in the flash, such as position, fuel calcs and stuff if you are going to use that as well, and boot the kernel from the HD (make sure you can boot from that sucker)

    Flash is probably your best bet
  • Posted by Stephen "The Carp" Carpenter:

    Who says the CPU has to do it?

    WHy not make a hardware MP3 player on the
    parallel port (netwinder has one I hope) and
    then use the computer just to serve up the data.
  • Posted by Professor Krakho:

    I actually work for a company that is starting to develop a "rugged PC" for automobiles. Check it out if you are interested at http://www.fleetpc.com
  • Posted by Imru al-Qays:

    You'll want to look into the slightly unwise world of unofficial engine computer mods (mostly people tuning up the engines in their Miatas and Z3s, but who knows, maybe a pickup would work). Which raises an interesting question - if you had a machine running in your trunk, could you link it into the machine running under your hood (so to speak)? I myself would rather make a wearable that I could run off a dynamo on my bike, but the power supply is a little less consistent... TB.
  • Posted by JKX_1:

    I'm using a 486-DX2-100MH w/ Win 95 and only 24 megs doing fine.
  • Posted by Davo-CC:

    This may be an expensive option but I seem to recall there being a type of refrigerative storage container that runs on comparatively low power which also contains extensive insulation and a fairly small open core. This device is used to store medical supplies in remote areas, it is powered by a solar cell but I couldn't tell you much more about it than that (having only seen one on television a couple of years ago).

    This would mean that you mount your PC inside the core of the box, and keep the unit on low power - perhaps a Libretto or similar device would be good for this purpose (they're fairly quick, very small, etc.).

    You could power the cooling mechanism from a small solar cell array, that could perhaps be mounted under the rear window or even on the boot of the car; this is how the device was designed to work.

    Another possible solution would be to use a small eski such as one of those Coleman coolers (for foodstuffs) and keep it inside that; something with insulation. I'm aware of cigarette-lighter powered versions of this with a small refrigerator built, it may be a bit over the top but it may provide a cooling solution for you.

    They also let you put in foam padding of various grades to allow some form of shock protection inside the box, create the foam pads correctly with varying grades of foam heaviness and presto, a cooled protected PC. As for screen - that may be a different matter. I wonder how well those car-based LCD screens take the heat, my experience with overly heated LCD screens has never been good.

    Hope this helps!


    DT

  • Have a look at http://efi332.eng.ohio-state.edu/ for details of a Do-It-Yourself Electronic Fuel Injection system. Not exactly a PC in your car but it could be usefull if your looking for a partially sorted car computer... I'm personally going to be building an EFI system but you could use it for more general things.

    PCs in general suck for cars and embedded systems... too heavy, too much power, too fragile. Things based on Motorola chips are good... Hitachi SH1 is another good, powerful thing to look at.

    Use RTEMS as your Real Time OS. Linux is OK in PCs but is the wrong shape to fit in embedded systems.

  • the comptuer in my truck is having porblems anyway, how do I find out what I need to control it though?

    I presume that I need to put a (variable) voltage/current to the fuel injector, and read all the sensors and decide what to do. How do I go from there to doing it though? What numbers, and how time critical is it. I have a throttel body which I presume has less critical timing requirements, but I need to know if linux will do it, or if I need a more real-time OS.

    No playing quake on the system, but I'd know more about what is going on.

  • BTW, I'm the one who sent this question to Ask Slashdot.

    I live in Las Vegas, Nevada, and yes, temperatures in the trunk can reach 100C(212F) in the trunk when the car is parked out in the sun in the summer months when it is 115F outside. The highest temp I recorded in the trunk is 221F, according to my gallium thermometer. Yes, this is above the boiling point of water. Were it not for the antifreeze, the radiator in a parked car with the engine off would boil over (and does for lots of tourists not prepared for the heat!). Welcome to the desert!

    Silly side note: The local news ran a story about this woman who bakes cookies in her car during the summer. She puts the cookie dough on a pan and sets the pan on the dash of her parked car while she's at work, a little later in the day, yummy cookies for the office staff! I kid you not!
  • BTW, I'm the one who sent this question to Ask Slashdot.

    I live in Las Vegas, Nevada, and yes, temperatures in the trunk can reach 100C(212F) in the trunk when the car is parked out in the sun in the summer months when it is 115F outside. The highest temp I recorded in the trunk is 221F, according to my oven thermometer (which I tested for accuracy). Yes, this is above the boiling point of water. Were it not for the antifreeze, the radiator in a parked car with the engine off would boil over (and does for lots of tourists not prepared for the heat!). Welcome to the desert!

    Silly side note: The local news ran a story about this woman who bakes cookies in her car during the summer. She puts the cookie dough on a pan and sets the pan on the dash of her parked car while she's at work, a little later in the day, yummy cookies for the office staff! I kid you not!
  • not where are you driving, where are you parking. If you live in phoenix, and you park your car outside in the summer, it can get that hot. . .
  • Just remember that your replacement needs to be 100% reliable. A malfunction could conceivably damage the engine (not to mention the fact that a failure while cruising down the highway could have other disastrous consequences).

    But it shouldn't hurt to tinker with. Sounds like fun, actually.
  • Garages nowadays have computers that they simply hook up to your engine computer. They're able to diagnose a lot of problems that way, since the engine computer can provide the garage computer with tons of data about how the engine is functioning.

    It seems to me like this could (and SHOULD) be easy to hook up to your own PC. A lot of the information would certainly help those of us that are capable of making repairs to our own cars.

    Not to mention the geek factor...
  • The ethernet idea is a pretty good idea. You could wire up ethernet jacks in front and for the rear seats and perhaps even one next to the gas cap. It'd be cool to be able to just plug an ethernet cable into a jack next to your fuel port (and what's a more logical place?) to do updates to your car. You could even run Samba on it and have your car appear in the Network Neighborhood for the Windows machines on your home LAN. Or, you know, you could go one step further and get a wireless network card...

    I'd be wary, though, of using a 12VDC -> 120VAC power system, since you're just having to drop the voltage again to a low-voltage DC source for use with the computer. Those conversions are going to cost a lot in terms of power and heat. A far better solution is to find some way to stabilize the 12VDC power from the car and drop it to 5V or whatever for use directly with the computer.
  • Do you have a URL for "Inside Technology?"
    I've been working on this type of project for my car, and I've been having trouble finding a PC-on-card with LCD screen support.
    www.arisecomputer.com (or something close to that) has some awesome DC power supplies for sale.
    www.cellcomputing.com has the REALLY tiny stuff. Pretty expensive, but not really more than $1000.
    That seems like a reasonable price to me, dude. Industrial PCs are pretty expensive.

    Actually, the only reason that I'm building my own is that none of the other kits have the proper level of display quality that I'm looking for. I definitely want some kick ass visualization on a 6" LCD, as well as touch-screen support.
    If you want to talk about this, send me some e-mail.

    At the very least, though, let me know the URL for Inside Technology.

    Thanks.
  • This is the goal of the CAJUN (Car Audio Jukebox UNIX) [current.nu] project, isn't it? :-)
  • Just because the web site isn't updated doesn't mean the project is dead. 3 months isn't that long to go without an update in HTML, and != no work on code.

    PS. I think there may be an update by Monday, but I am not sure.

  • Take a look at Alpine's solution to the "attractive nuicanse" (sp?) problem: IN-DASH MOTORIZED/HIDDEN DISPLAY! [alpine1.com]! This is definitely my choice. They have a kick-ass GPS system that ties into the display as well.
  • Sounds like the requirements for a notebook PC.

    Sean
  • Now you're getting into something considerably more complex than simple stuff like MP3 playing, GPS, and anything else you might normally use your computer for. Check out the diy_efi mailing list (Do It Yourself Electronic Fuel Injection)...you might be surprised how complicated things really are. http://efi332.eng.ohio-state.edu/diy_efi/ [ohio-state.edu]

  • autoLinux (Score:1)

    by tgd ( 2822 )
    Well I was getting ready to announce this anyway, so now's as good a time as any...

    I've been working on developing hardware and software combinations for about six months now for using Linux in a car. I've recently been given a copy of the TIGER/Line database and am working on a format for storing navigation mapping data in a compact enough format to use in a car for GPS automotive applications under Linux.

    There's a mailing list for the project, even though its really in its infancy. The mailing list is meant for discussion about automotive uses of Linux, as well as hardware and software issues with using it in that environment.

    Anyone interested should check out:

    http://www.bangsplat.org/autolinux

  • The problem with old 1x, 2x, 4x CDROMs is that often, they won't read CD-Rs reliably - they were around before CD-R was.

    Hugo, empeg

  • Comment removed based on user account deletion

  • (I can't seem to remember to TAB and not RETURN!!)

    When was the last time that you were zooming down the freeway and you wanted to run a spreadsheet? Or play Doom?

    There is a time and place for PC's and driving is not one. What you need is a simple computer that only does exactly what you need- that's not necessarily a full pc.
  • no, take a DiskOnChip, go to m-system [m-sys.com]
    there's industrial SBC (single board computer) or "biscuit PC" that can handle all this
    --
  • there's 144Mb DOC2000 i think, also i know SBC with 2 or more slot for DOC, there's also add-on card (ISA or PCI?) with 4 or more slot...
    however DOC require a slot and a driver, but you can use flash IDE drive, you just plug them on your IDE ribbon and that's it! no movable part, only memory!
    --
  • I've been working on this problem pretty intensively for the last 2 years for a company that makes automobile navigation systems. We're using Linux (currently 2.0.34) for our next gen version (out later this year). As a lot of people have noted, storage is probably the biggest issue. Its not too hard to meet automotive environmental specs with silicon, but commonly available rotating media are a different story. I'd love to be able to use solid state storage, but both maps (for navigation) and MP3's take up so much space that solid state will not allow us to build an product with an attractive featureset within our target price of less than $1000 (hopefully, a lot less). CD's are more sensitive than hard drives all around, but the failure modes on hard drives are more catastrophic so you need to be extra careful with them. Shock mounting handles this problem nicely and inexpensively in all cases, although building the unit so that your typical auto installer can't kill it by dropping it is still difficult. The bigger problem in the real world is temp. In principle its not hard to make inexpensive DVD's, CD's, or hard drives work over large temp ranges, but nobody does because the volume market is all in office equipment. The stuff that is built for cars is very optimized and not adaptable to other applications by and large (like a data device) - I know, I've done it both ways. In the end, if you want to make something inexpensive you either have to compromise on some things (mainly temp range) or spend a LOT of money tooling up your own storage device.

    Our device uses a very fast MIPS processor, has audio on board (the user interface is speech recoginition/synthesis) will come in hard drive and DVD versions, is spec'd to work from 5C to 55C (portable use or car interior, not trunk) and is about the size of a fat walkman. If you are serious about developing software for such a platform contact me, maybe we can work something out.
  • I wouldn't even _think_ about attempting this, and I design engine computers. They are far, far, far more complicated that you might thing, especially newer ones which often control much more than simple combustion parameters.

    First, you won't be able to do it with Linux, or any other standard PC unix. They simply aren't designed for this type of application. You'd have to go with some kind of RTOS (Real Time OS), and those generally cost big dollars.

    Second, there is a huge amount of I/O on an ECU. There's between 1 and 8 injectors, 2-8 ignition coil outputs, air-flow sensor, throttle position, inlet air temp, crank position, cam position, knock sensor(s), and that's just to run the engine. Then there's all the other outputs that the ECU controls.

    The environment is very harsh as well. During a load-dump, you will see 50V+ voltage spikes on Vbat. Temp. range for a ECU mounted on the passenger cabin side of the firewall is ~-40C - 100C. If it's mounted in the engine compartment, bump that to 125C. It needs to withstand 2+G of vibration as well.

    If you're looking for tuning opportunites, there is probably an aftermarket chip of some kind for your truck. If nothing else, Eddlebrock and Holley are starting to make fuel injection systems.
  • One question that has come to mind everytime I've looked at CAJUN is "how will they survive in hot weather?" A local video store has a bunch of tapes on display that were melted by being left in hot trunks. While I know that most logic boards are imade of stouter plastics, but isn't there still a lot of potential for heat related damage?
  • ...one of those cheap Multias selling a while back will work well. Grab yourself a power inverter and a pair of speakers, you'll not only have an in-car mp3 player, but a very portable one at that. The friend of mine who has done this wants to fit some small type of monitor, to see what you're actually typing, or rig up something like say to read it back to you.

    weeber
  • Why would you want it that fast? Most MP3s are 128K/s ... so something around 200K/s is just fine. It's cheap (CD media is still something like $2 CDN) and you can fit around 10 hours of music on one CD. I've never understood all these hard drive and flash based things, sure they're shock resistant and stuff, but it'd be much nicer if the OSS hardware building community would settle on a standard for MP3 CDs or somesuch.

    You could use less and cheaper non-static ram to buffer the songs a decent amount to make it somewhat skip tolerant ... give those old 16Mb simms a home?

    Would such a thing be feasable?
  • I'm currently working on a nice DC power supply for the car/computer project I'm doing. As of this moment, I'll be using National Semiconductor's SIMPLE SWITCHER LM2678.

    Power inverters seem like a stupid waste. DC->AC->DC is pretty silly. And not terribly effecient.

    I'm planning on running one of advansys's biscuit PC's, which conveniently only requires +5V. :)
  • It wouldn't work out of the 'box' for that, but you could add a MAS3507 (MP3 decoder) and a DAC to get an audio signal. Then just write a little program to send the MP3 bitstream to the decoder.

    The CPU is the same one the Palm Pilot uses. It's a great chip for embedded stuff like that. It also needs no cooling, perfect for a car. The LCD drive capability is nice too. Maybe one more chip to control a touchscreen and you've almost got a Pilot.
  • Simple soultion. Get a small Gell-Cell battery to run it from. Then connect that battery to the car power supply with a charging circuit. Now you have a backup power supply. You need to put good filtering on the supply from the car, large caps should help. Or, better yet, find a way to power it isolated from the main car supply. A switching power supply with a small transformer would do. Most DC/DC converters are built like this.
  • I used a Cyrix 6x86 at 120MHz (called the P150 I think) and it played mp3's fine, but couldn't do much else at the same time. So unless you're worried about anacron doing an updatedb or something while the mp3 is playing, you'd have to go lower than that to lose mp3-playing capability.
  • Actually DC-AC-DC is more efficient than a straight DC-DC. However, the NatSemi part is recommended, it uses switched capacitors.
    Capacitor switching is the electrical equivalent of using flood gates in a canal when changing aquatic elevations (voltages).

  • Putting a computer in your car demands a change in the way you think about computing. Especially since most applications are going to be very specific (i.e. GPS or MP3 audio). Connecting a 101 key keyboard and/or a VGA monitor is overkill.

    A simple serial or parallel-port based input device is sufficient. Many people are opting for small LCD displays for visual output.

  • xaudio works *fine* on a netwinder, I'm happy to say. :)

    The implementation for the ARM chips uses fixed-point math.

    _Deirdre
  • Check out the mailing list archive at the MadLUG (Madison Linux User Group) website at http://madlug.jvlnet.com [jvlnet.com]. One of our members, who is also a sysadmin at this ISP, has done this rather successfully.

  • I would check out the companies that make a ruggedized equipment chassis. A lot of them sell CPUs to install in them. You might even find disk drive enclosures that can operate while you're driving (pretty scary thought, though). Someone recommended laptop drives which would be a good idea since their small size should make them somewhat less susceptible to shock problems.

    The automotive environment is a very harsh environment to build for (which I'm sure you've figured out) what with the heat, vibration, moisture, and power requirements. Hey! Is NORDEN still building computers? If their's can't run in an automobile...

    Hope this works out for you. I'm sort hoping that you'll come up with an optional heads-up X display for the passenger side (for safety reasons, you understand) with a glove box mouse.

  • Agreed about the problems with temperature extremes and HDs. It's probably 140F inside your car if it's locked up on a hot, sunny, summer day. And, at least here in MN, it would have suffer through -20F -30F. A normal HD's not going to survive.

    One thing to think about might be a swappable drive bay. Then you could remove your drive just like you remove the faceplate for the CD player ;-)
  • When was the last time any of you were in a police cruiser? Or a utilities vehicle. They have mobile
    computing figured out. You may not like the way they do it however. Most have laptops mounted on a special rig so that it can be accessed from the drivers position. Depending upon the size of your vehicle this could interfere with the passenger. Otherwise its probably the best thing going.
  • Three problems, temperature, vibration, power.

    Temperature: The obvious answer is insulation. So, put an ice cooler box for housing the unit in your trunk surrounded with pink housing insulation. That should keep it from getting too hot or cold.

    Vibration: The only part of a PC really sensitive to vibration is the hard drive. Make a small wooden box, and suspend the hard drive inside using rubber surgical tubing. I use this stuff as a DJ to suspend my CD players. It's strong enough that it won't break, and is nice and stretchy to insulate againsed any shocks. Put the whole deal inside the cooler box.

    Power: You can buy power adapters that should do the 12 to 120 trick at your local electronics store such as Radio Shack. Just note what type of power supply your using. Assuming you don't wont to buy an LCD panel, I would recommend getting a 7" POS terminal screen, it shouldn't suck up that much power. Hell, just find a 286 clunker laptop and rob the screen from that, and hopefully be able to wire it up, or use the whole 286 as a terminal for the real box in the trunk. Cool, wire an ethernet into your car, and have the server in the trunk do DHCP so your friends can come to the car and just plug in their laptops .... mmmm .. quake on the road :-)
    If you have too much trouble with the power, talk to some of the competition level car audio guys, they're really good at those problems. but the solutions arent that cheap.
  • You will want a big Sun case that hold noise in.
    I know someone who got a Sun case that was being
    thrown away. What you are looking for is in the
    style of a little refridgerator. They are cases
    that look like mid-towers but they are fatter and
    they have a door-like thing on the side. For a
    fan you'll want to run a tube offa the car's A/C
    system into a hole on the side of the case. Just
    put a lot of electric and duct tape on there.
    Throw in a tight motherboard, chip, RAM, Hard
    Disk, Vid card and sound card and there u go...
    You might wanna get a PCMCIA connector and stick
    a cellular modem on there too! think about that!
    - me... ;-)
  • I used an LPX case, Cyrix MediaGX 266 CPU/sound/video, 1.6GB HDD scavenged from my broken laptop, and a 10" active matrix screen off an old IBM Thinkpad. The low profile computer case sits under the drivers seat, the screen was built into my dash by a local stereo shop (they also wired the PC audio into my radio speakers), we installed a small APC UPS to filter the power, and the whole thing runs (mostly) off of IBM ViaVoice (yes...this is a Windows95 box). My cell phone hooks up to it for checking email or Slashdot, I run DeLorme mapping software for finding my way around, and I can play Quake in the parking lot while the wife is shopping at the mall.

    I can't give an exact construction price since I already had a few of the parts, but I would estimate it somewhere around $1000 and 10-15 hours of labor. Of course, if you wanted to play MP3's on this thing I'd recommend springing for a better sound card (the GX sound support can be shut off).

    Oh, and don't flame me for running a Windows PC in my car...I'll switch it over when I see a good voice recognition prog for Linux. I've already found or written Linux replacements for all of my other SW, but the voice rec is the key to the entire operation and I can't do without it.
  • chech out http://www.jarcom.com/inmotion/ for a build it yourself DC-DC converter.
  • While I would agree that the DOS/NEWDEAL OFFICE combination is an excellent low-power solution for running a "modern" OS on old hardware, this solution just doesn't quite give you the MP3 playback capability that we're looking for here. I ran Caldera DR-DOS [caldera.com] and NewDeal [newdealinc.com] on my P100 laptop for quite a while and it worked like magic (until I finally installed linux). If you haven't, you should really check out www.newdealinc.com for information on a really awesome alternative desktop operating environment for 8088-80386 PCs (and for people not wanting to run Linux.)
  • I've used car-mounted Linux boxes before... laptop hard drives (and even some conventional 3.5" drives) can be used, but you have to make sure that you properly mount the drives.

    A better suggestion, however, is to just use CD-ROM/CD-R for everything. My vehicle-mounted MP3 box uses a conventional ATAPI CD-ROM drive with a small amount of FLASH disk to boot from, no problems. The "display" uses a BASIC Stamp II Microcontroller, a rotary switch, a couple of buttons, and a two-line LCD I picked up at one of the ham radio swaps in Southern California, and connects to the serial port.

    Most importantly, since there are no writable file systems (except for the small RAMDISK I create on bootup), I don't have to worry about power problems resetting the machine. A decent quality voltage regulator supplies 120V AC (although a friend tells me that there is such a thing as a 12V DC computer power supply out there).

    I'm working on a webpage for my project, but it's not quite ready yet. Go to my webpage and fill out the guestbook entry there, and I'll get back to you when the page is finished.

    Now, to just finish my wearable...

  • First off, I live in an area where the temperature rarely gets below 50 degrees (Bakersfield, CA.. although it snowed here last week). Also, I drive a pick-up truck. The MP3 box is mounted in a small enclosure behind the seat, and could conceivably be mounted under the seat of a luxury car or even in two standard DIN-style mounts in the dashboard of most cars.

    If you really have to have it mounted in your trunk, I would just simply build a small, insulated enclosure with a small blower in it. After a minute of operation, just about any Pentium-class machine I know of would produce enough heat to get the internal temperature of such a chassis to well above 80F. To my knowledge, there is no danger of allowing CD-Rs to freeze, other than concerns about dew freezing on the disk itself.

    Lastly, many consumer electronics manufacturers (Kenwood, Sony, et. al.) produce trunk-mounted multi-CD changers. If the environment is good enough for that, I personally don't see any problem with putting a MP3 player in the trunk.

    As usual, however, your milage may vary. It works for me.

  • I'm making an embedded system for my car. It'll have a HUD using bright LEDs. It will perform data aquisition on the car using analog to digital converters, counters, and other gizmos. There will be a microcontroller that runs autonomously, communicates with many ICs over a serial bus, sends data to a PC (when installed) over a serial link, and stores its code in ROM. Most of the components will have an industrial temperature range (from -40C to 125C, or -20C to 70C depending on the part). For power, a 7805 voltage regulator and some capacitors will do.

    I'll have this thing attached to my car, on top of my dash. When the car is running, the system will be running (no boot period). And when the PC finally come up (a circut will prevent it when the temp is to cold or hot, then it has to boot) it can get the car's data in real time, and process it for whatever purpose.

    I've started working on it. Its quite feasable. I hope to have a test system that will tell me about the pulses going to my spedometer and tachometer (there is no tachometer in my car, but the pulses do make it to the dash).

    To make this project possible, I had to get documentation on my car. I connacted Helm [helminc.com] to get the service and electrical manuals for my 1989 Honda Civic. I got nice new books that tell me everything I could ever ask about my car -- every electrical circut is fully documented, along with info on how to replace axles and engines (everything is there).

    I've already wired up my dash (nothing connected to yet), and made a few test circuts. I'm having way too much fun with this!! So much, that I haven't documented any of it on my web site -- no time!

    Anyone else intrested in this microcontroller approach?
  • DigiKey [digikey.com] has some devices called DC to DC converters/power supplies. Something like that. The 25W one (most powerful one they have) outputs 5 and 12 volts. I'm not sure if 25W will be enough, but its more than IC's tipically can handle, and you could use more than one unit.

    Or, you could try voltage regulators and capacitors connected to computer style power connectors.
  • I have the problem on the other end...
    My trunk gets cold and the CD-ROM refuses
    to spin up, or when it does, the read is
    slow and error-filled. I guess it would be
    a good idea to have it copy the files to the HD
    then play 'em.
  • I bet people would buy prefab DC PC power supplies
    for projects like this. You should sell 'em if you get it working right.
  • An ideal system for this kind of thing would probably be a notebook computer w/ a damaged screen which could be bought for less $$.
  • I've been thinking about doing something like this for a while now. As far as I can tell, the largest problem is the PSU. I could make one myself, but, alas, I'm lazy.... And pretty incompetent when it comes to electronics. Anybody seen a schematic for a 12V PSU? Or, even better, knows of a place where I can buy one...?

    I've been looking at an industrial pc-on-a-card from Inside Technology with built-in LCD driver, optional Flash-disk, VGA, serial, Adaptec SCSI, dual ethernet-controller, USB and a 233MMX CPU. Price: about $1000. Is this expensive....?

    I've also got a 6.2" TFT LCD-display.... Hmm... If i rip out the ashtray, maybe it'll fit...?:)

    This could be the ultimate geek-mobile....:)
  • I've been thinking of using a DC-DC converter myself, but I'm a bit nervous as to what will happen when I turn the ignition on... The voltage drops dramatically, and you might get some serious trouble keeping the motherboard alive. Could try some large capacitors or sumpthin'.

    I've found a compact keyboard just small enough to mount on the glove-compartment lid. Full 102-key thing...:)

    I've been thinking of putting the kernel (and some basic utilities) in flash-memory, and using a cd-rom drive to store the MP3's on. To minimize the risk of drive-damage, you could copy the songs to a ramdisk before playing them.

    Would've been nice with an IrDA link to connect to my in-house LAN...:)

    As to the graphics; I thought it could be nice to be able to use the computer to do more than just play MP3's. I've been thinking of hooking up my GSM phone to it via the serial port (Nokia CDS). I even believe there is a linux-driver for it...!:) Could read my email in the car...:)

    Just gotta fix some minor financial problems first....:)
  • I been thinking about the same thing, though I didn't think about alot of the things mentioned above. I have a pickup so I thought I would rig something up under the seat which contained the board, HD, etc. but I would want to set up a small monitor of sorts into the dash. Where would I get a small enough monitor (5" to 7"). Also, what about input devices, I really don't want to have a full size key board floating around in my truck...I don't have much room to begin with.
  • PC/104 is a perfect solution. You can find Pentium boards with SCSI, IDE, 100BaseT, and flat panel drivers that run on 5V. Just regulate the 5V from the 12 to get rid of the noise. Then you can throw in a solid state drive and away you go.

    We have a linux box in this configuration running a gun sight off of a FLIR. Works like a champ. I'd like to see a car that can generate as much abuse :-).
  • There is a huge market of industrial PCs out there. They have all the rugged options that you are looking for.

    Flash or solid state disk is the best but expensive. Laptop hard drives on vibration mounts are the next best thing. You can get multiple gigabytes, it's low power (5V only), and it's shock tolerant.

    Watch out for high voltage (50V) spikes and noise on auto power.

    Check out www.cyberresearch.com and get a catalog (it's better than their online stuff).
  • The original post said 100C, not 100F. There is a very big difference! The inside does get quite a bit hotter than the outside, but if it ever got to 100C you'd have other things to worry about than the PC in the trunk!
  • Basically all you need is caps to stabilize the +14.4V alternator output. Then run that thru a 7805 and 7812 (+5V and +12V) and a DC-DC IC convertor to provide the -5/-12V power. The largest problem is the +5V current. I've made some measurements and it seems to be somewhere in the 3+ Amp range. This can be accomplished by ganging a few 7805 regulators in TO-3 cases which can handle 3A each, when properly heatsinked.

    Don't bother with 120VAC invertors, they're bulky and overkill. I also like the idea of using Peltier devices for the heating/cooling needs of the components. Don't forget humidity!

    Why don't I just come up with a schematic and post it? Anyone interested??? I'm going to build one for myself anyway.

    Greg
  • I agree with what you are saying about the 7805s in parallel, but the only real cause of failure is overheating. In any event, there are 5A ones available which would be enough current for me.

    I was just checking pricing on switching power supplies and while easy, you're right, they're not cheap. I'm looking for cheap and nasty.

    I've been working on my schematic based on a previous design I did for a different application, and I'll hopefully have it posted tonight.

    Even with the PC104, you'll still have to contend with +5V.

    I'm interested in your EFI project. I have a good idea how OEM systems work, and have thought of a few ideas to add to them.

    Greg
  • A number of you have pointed out that the 7805 is incapable of handling the current, and even if it could, it would need a lot of heatsinking. My apologies... I probably should have explicitly said "I know the 7805 can't do the job, but there are 7805 "like" devices that can handle 5A, when properly heat sunk." Everyone seems so concerned about efficiency, but we're talking 100W maybe. Does your car have power windows? Well, they'll draw more juice than this thing ever will. IMHO, I'll take the compactness and low cost of my solution over the efficiency of the inverter-standard PS. Besides, I NEED the heat, since I live in Ontario, Canada, and want to use the final product in the winter.

    I've thought about doing a design for a switched mode PS, but here's my problem... The transformer. I'd like to come up with something that we could all easily repeat, and a hand-wound transformer is not that. Anybody got any thoughts???

    Greg
  • I've got an Intel Pentium 90 machine running in the back of my vehicle serving as a mp3 player. The only modification I made to it was to pack the hard drive into a bunch of hard foam within the area for 5 1/4" devices. I stole some foam from hard-drive shipping boxes at work. Before I packed the drive in foam I had to format the drive a few times dew to vibration screw-ups.

    For power you should keep the motherboard and such a few steps away from your alternator. This can be done through a number of different methods, I use a 300watt inverter (way bigger than you should need) with a small ups plugged in between the pc and the inverter. Before I put in the ups I had to add another car battery and a battery isolator to fix a problem with the machine rebooting sometimes while starting my engine.
  • For this project and generally, what are the good parts houses out there? I already know Jameco, but that's it.
  • For example, the Swiss company Digital-Logic manufacturs various fan-less PC/104 or single-chip modules in the range from 386 to Pentium which can be equipped with 2 to 144 MB FlashROM disk-on-a-chip modules, or even 1" harddrives.
  • The first thing to pop out of its sockets are always the SIMM or DIMMs, since those kind of sockets are not very resistant to shock or vibrations.

    If you put a anyting on a SIMM or a DIMM into a car, it will have popped out by the time you shift into the first gear. :-(

  • I would like to know how you where able to adapt the laptop screen to a svga card? I'm looking to install some sorta of flat panel screen for my car computer, and it would be very easy for me to obtain a laptop screen... any info on how you hooked it up would be most helpful!

    Thanks,
    -Mav
  • First of all, as someone else already suggested, DON'T use a harddisk, use flash. It's expensive, but not more expensive than it will be if you go with a harddisk and have to exchange it regularly because of malfunction.

    Using flash also goes a long way in solving other problems: a flashdisk draw a lot less power than a regular harddisk, and thus also generate less heat.

    Take a look at Jumptec's pages [jumptec.de], too. They're the ones that produce the DIMM PC that was features on Slashdot some days ago (world smallest web server). They produce a whole range of PC's intended for industrial use.

  • Hey,

    I have been looking all over for around a 6" LCD
    display that takes a standard VGA plug? Where did
    you get yours from?

    adam@kpower.com
  • Why not use a ThinkPad 500 series (or equivalent)?

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