How to build a plug n play 12 volt mini computer

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					How to build a plug 'n play 12 volt mini computer for less than $400 even if you’re not a computer guru. What’s the best computer to have on board? Laptop? Desktop? Custom build? The answers to that are as varied as the boats we sail. They all have pros and cons ranging from price to portability to performance. The type of software you intend to use aboard is also tailored to each person’s needs and desires, which in turn puts specific demands on the computer system. In many cases a laptop is the simplest solution. While a laptop will serve us as a backup and for portability, we also wanted a dedicated ship’s computer. For that purpose I had considered just taking our desktop but the power draw was unacceptable and would be worse when powering it from the inverter. So I looked into the alternatives and found a few specialty suppliers that offer 12 volt mini-computers. Prices start at $900 and go rapidly up, especially for the options I wanted, and so were out of my desired range. Further research showed that putting a small-case computer together was probably not too difficult and was very cost-effective. I also discovered that a computer runs on 12 volts and 5.5 volts, so the power supply in a computer is converting 110ac to 12v dc and 5.5v dc. If you run a desktop or a laptop on an inverter you’re converting the power supply twice, once in the inverter and again in the computer power supply. Of course this introduces way too much inefficiency. The secret ingredient is the power supply. All you need is a power supply that will stabilize and split 12 volts into both a 12 volt power source and a 5.5 volt power source, and then get the power to where it needs to be. Searching the internet turned up several electronic supply companies that in the past had built 12 volt power supplies. When I called I learned they no longer produced them due to lack of demand. I didn’t give up there, though. Further research led me to the discovery that there is a growing market for automotive computers for high-end audio and videophiles. At least one company supplies 12 volt power supplies for that market. The power supplies are designed to plug directly into a motherboard and offer stabilized voltage, on/off shutdown options and a working range of input voltages from 6 to 30 volts. What worked in the automotive market was perfect for my purposes. With that discovery I was on my way. Next I had to decide what to build; a micro-box unit simply for navigation, a full-featured unit capable doing anything a desktop could perform, or something in between. While outfitting our Island Packet 38 we desired several things in a computer. Our “want” list was this:     An external wi-fi antenna for maximum range, which required a full-size PCI card slot. A digital TV card so we could use rabbit ears for local TV reception when in port, which also required a full-size PCI card. A big hard drive for my music collection. The ability to run navigation software using NMEA input from a GPS.

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Enough horsepower (memory and speed) to run video editing software and even more storage for videos. A cd/dvd burner.

In other words, a desktop computer much like you might have at home, except we also wanted:    A small case so it would sit on a shelf out of the way. This would eliminate the need to setup and take down a laptop when we needed the nav table for other things. Direct 12 volt power thus eliminating the need for an inverter with its associated losses. Low power draw.

This project also had to be pretty basic as I am not a computer expert. I needed a parts list of components that I could order, plug together, and run. That was the complicated and time-consuming part. After much research I had my list. I got online and started ordering with great anticipation. As the boxes started showing up I read all the directions for each component and tried to understand how they worked together. It really wasn’t too bad, not unlike figuring out that new digital camera for the first time. I came up with a wish list that fit our specific requirements: These are suggested parts from current sales - but availability and prices change daily so you may have to find comparable items. Here are the best deals from tigerdirect as of this writing: Motherboard- 256 mb video built in, usb, lan, sound, etc: Two gig memory:


Microprocessor chip, dual core for faster video editing: Case. Smaller ones are available; I used this one because I wanted at least two full size PCI slots for a TV card and a wi-fi card that I already owned. This one fits on the shelf next to the electronics panel: Serial ata laptop drive, 250 gig. A laptop drive is recommended for a boat as a desktop drive won't take the G-forces for long and a laptop drive uses much less power: Dvd burner, with LightScribe, which might be handy on a boat - etch the label on the disk itself vs using a marker. Cost was comparable to a standard burner: And the secret ingredient, the 12 volt power supply. I ordered two, just for experimentations sake. This first one is less expensive and still has a full 200 watts output. You'll also need the 24-20 pin cable adapter and the P4-ATX cable listed at the bottom of the link: The second one is a 250 watt supply, which is overkill, but it has a wide input voltage range (6-30v) which might be useful to dampen out the normal voltage fluctuations on a boat: Except for mounting the power supply this was a plug and play build. I used a homemade mount, locating the power supply directly in front of the rear case fan. The power supply needs to be securely mounted and ventilated. In my case I simply used metal screws into the case framework with an insulating barrier underneath the power supply. After reading the directions several times and double-checking all the cable connections I fired it up. It came to life with a blink of LEDS and the whir of fans, indicating I’d hooked everything up correctly. Loading and updating Windows was straightforward and then it was a matter of loading all the software I wanted to run. After a few days of tinkering with it I disconnected the power supply and plugged in the 12 volt unit. Hooking the wires to my wife’s minivan battery gave me a 12 volt power source and with some trepidation I again pushed the button. With the same glow of lights and whir of fans it booted up just fine. Success! The power consumption was a big concern as that was the main point of this project. After completing the new computer I tested all of the computers we own for comparison. All readings were taken while burning a dvd and playing music. 110v was measured with a Kill A Watt P4400 meter and 12v with a digital voltmeter set to amps. Note: These are before any inverter losses are added. Using amps = watts/voltage here’s what I discovered:   Desktop: 160 watts (13 amps @ 12v), 40 watts (3.3 amps @ 12v) of which are used by the old fashioned CRT screen. Laptop: 80 watts (6.7 amps @ 12v)


12 volt computer: 4.2 amps @ 12v burning dvd and playing music, 3.6 amps @ 12v just running software. This does not include monitor.

This was a significant decrease in amp draw, making the project a success in my book. Total cost using the 200 watt power supply was $373.89, or $438.94 using the 250 watt unit. In retrospect an even smaller power supply would have been fine, and less expensive. This price could be trimmed even more if you didn’t need all the bells and whistles. Less memory, a smaller hard drive and a standard microprocessor chip would still make a nice computer and would cut the basic cost even further. This gets you the computer, then you need the peripherals; software, monitor, keyboard and mouse. I didn’t include these items because they vary greatly in type and price. For instance, you can get a wireless keyboard and mouse at newegg for $17.99: A monitor will run anywhere from $100 to over $300. I am still searching for a reasonably priced 12v monitor. They are available at a premium, but I already own a nice 19 inch flatscreen and can’t justify a 12 volt one at around $300 quite yet. Running the monitor through the inverter does introduce some loss. The monitor pulls 2.9 amps including inverter so there is room for improvement. To complete the system you'll need to buy a copy of Windows: 1&pf_rd_s=center41&pf_rd_t=201&pf_rd_i=B00022PTRU&pf_rd_m=ATVPDKIKX0DER&pf_rd_r=1A GJWX8E225416KS1Q6Q I bought XP Home, others might prefer Vista or XP Professional. Using this “System Builders” version you then have to get online and spend some time updating, but this is the cheapest way I could find to go when using Windows. Then you'll need to install whatever software you desire, navigation, word processing, video editing, etc. Our computer now sits out of the way on a shelf and the keyboard is in a drawer until needed. The monitor is mounted up and out of the way so that we can watch DVDs in the evenings from anywhere in the salon and doesn’t need to be stowed when underway. All the electronic charts fit on a fraction of the hard drive, my wife can edit videos to her heart’s content and our entire music collection is a mouse click away.

Happy building!

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