Power requirements for pc..

[Bradley]

I too have a lot of interest in a mini-itx system for my boat. I am getting all different kinds of advice as to the appropriate motherboard.

Does anyone have any suggestions?

[sandy daugherty]

Thanks, MidlandOne, you made a lot of sense to me.

re: mini-itx: I'm installing my second ITX-based boat PC. The first is still running, but on Windows 98. The new one has enough memory and power to run Vista, but is currently loaded with XP sp2. I don't use them for navigation.

[majdrew]

then..

So I can power my laptop/notebook off the 12v dc batteries, but I may need a step up dc dc converter.

Does the dc supply have to EXACTLY match the power requirement of the device? I mean, if the appliance is rated for 5v say, do I have to have a step down converter to get this, or if I have one rated at say, 20v, I have to have a step up converter to get this?
What if I plug the 5v rated one into the 12v battery? Would it matter?

Thanks for all the info, I'm learning a lot. Excuse the complete ignorance on the subject.

Mark

[witzgall]

This varies based on the equipement, but generaly no, you cannot do this, unless you wish to fry the device. If it can handle a wide range of voltage, then it will say this on the device or in the manual. Going down usually won't be an issue, but up is.

Don't ask me how I know....

Chris

Originally Posted by majdrew

then..

So I can power my laptop/notebook off the 12v dc batteries, but I may need a step up dc dc converter.

Does the dc supply have to EXACTLY match the power requirement of the device? I mean, if the appliance is rated for 5v say, do I have to have a step down converter to get this, or if I have one rated at say, 20v, I have to have a step up converter to get this?
What if I plug the 5v rated one into the 12v battery? Would it matter?

Thanks for all the info, I'm learning a lot. Excuse the complete ignorance on the subject.

Mark

[Delezynski]

Originally Posted by majdrew

then..

So I can power my laptop/notebook off the 12v dc batteries, but I may need a step up dc dc converter.

Does the dc supply have to EXACTLY match the power requirement of the device? I mean, if the appliance is rated for 5v say, do I have to have a step down converter to get this, or if I have one rated at say, 20v, I have to have a step up converter to get this?
What if I plug the 5v rated one into the 12v battery? Would it matter?
Mark

Take a look at the laptop power supply! It will have a label of some type that gives power in and power out.

If the power out, (the power going to the laptop) is equal to or less than 12 volts. Stop by a Radio Shack type store and get a 5 dollar converter. Make sure the polarity on the computer side has the proper setup and you are good to go!

If the laptop needs 19.5 (or some other voltage), get a small inverter to power it with 110 V. And once more you are good to go.

That same label on the power supply "brick" will tell you the Watts used, make sure the inverter is rated about 1.5 times the required amount. I would "Guess" a 200 Watt unit would do. And, you can use the small inverter for other things also.

Greg

[slomotion]

Originally Posted by cooper

You can replace the existing power supply with a 12 volt in unit.

Are you saying that there are 12 volt power supplies that can replace a standard ATX desktop power supply - with 12v, 5v, 3.3v output all wired to the multiple connectors, etc.? I've never seen nor heard of these ( no offense - there are lots of things I've never seen or heard of, but I try to keep up). Obviously, you could build one, but can you provide sources for off-the-shelf products?

[Ex-Calif]

This really isn't rocket science but a picture may be worth 1,000 words.

Laptop In-Car Power Supply (CVA099)

Not endorsing the product, just a sample of the 380,000 hits or so for "Laptop Car Adapter"

[slomotion]

Yeah, OK - know about those. I thought he was talking about a 12v input box that served as a swap out replacement for a 120/240v ATX power supply for a DESKTOP comptuter.

[scotte]

And remember it's not just the volts that matter - if you do get a DC-DC converter for your laptop, make sure it can handle the amount of current needed by the laptop. Many of the step-down ones that you'll find are designed for electronics with much lower power requirements - 500-750mA. Take a look at the output section of your laptop power supply, it's likely to be somewhere around 3-4A (i.e. 3000-4000mA), and match it (it's perfectly OK if the converter is rated for a higher amperage than the load).

[sandy daugherty]

Slomotion: You asked
"Are you saying that there are 12 volt power supplies that can replace a standard ATX desktop power supply - with 12v, 5v, 3.3v output all wired to the multiple connectors, etc.?"
Yes. There are at least a half dozen. This is (I think) the smallest:
picoPSU-120 12V DC-DC ATX power supply
I'm currently using this one:Logic Supply - Leaders in Mini-ITX & Small Form Factor Solutions
I don't think you want to try to use any old ATX desktop on a boat. If you do, consider this:
Logic Supply - Leaders in Mini-ITX & Small Form Factor Solutions for 250 Watts, 300W peak.

These are designed for automotive and embedded systems, but work fine on a boat because that can accept a range of input voltages.

My boat computer theory is to buy small and cheap, with off the shelf replacements instead of exotic marinizing.

[slomotion]

Thank you, Sandy! Those are really cool and not expensive. OTOH - now I gotta go build something.

[sandy daugherty]

Bradley: I just went through the mini-itx selection process, and made these decisions:
There's no reason to build a vista machine because there isn't any software I want to use that requires it. XP is stable. One gig of ram is more than enough, even for multitasking.

I still need one Db9 serial port, for an ssb modem or a gps. For everything else I need USB 2.0. I went with an externally powered USB hub to avoid overloading the PSU.

I want video output to watch DVDs, port images from Charplotters and forward looking sonar to various monitors, display lowlight camera, and more. This does not require a gamer's video card; even the earliest itx boards had this onboard. This allows me to display other charts on my chartplotters!

Heat is an issue because things that run hot have to be air cooled, which increases the flow of salt air through the system. Reduce the heat, reduce the corrosion. Use not the most powerful chipsets. Mount the unit in an enclosed location with a supply of dessicant stuff. Ventilate through the dessicant, with a flap at the top to ensure that air is pulled up through it.

Conformal coatings for circuit boards are ineffective until you get into the megabuck options. Do without, have cheap spares in vacuum bags, back up often, have selfloading core software on memory cards or thumb drives.

Have a laptop to take ashore for internet cafe's. Do route planning on the PC, load the route on a chip for the chartplotters.

[Whimsical]

I am currently using a VIA C7 mini itx with a car power supply for my home machine. It is a Via EN 1200 which is fanless. It seemed good for most applications untill I tried some video editing, good enough for the boat if you dont want Vista, as it wont load it even though Via says it will. It has 2 serial ports and dual headed video, but not for two VGAs. From memory it uses less than 20w with the DVD working, monitor additional of course.
I think if it is housed in a good sized sealed compartment it wont need any extra cooling so corrosion won't be a problem.
Good source of feedback for VIA products Welcome To VIA Arena ...
Pretty happy.

Mike

[cooper]

Yep, slomo

Those are really cool and not expensive.

thats the ones. I also used a laptop hard drive and CD drive. I am running windows 98 because it is nice and stable and works very well with the full Cmap. Cost wise was about $135 for the whole setup. I am going to keep it as a dedicated "boat box". Other stuff will be done on a lap top (like internet). This is the only way I know of to be 100 percent sure of keeping it virus free. Till some smart teenager designs one that can get out of one machine and go for a walk to the next....

ps I sprayed the Mother board and (everything else !) with the spray can, circuit board waterproofing varnish.


...ELECTUS DISTRIBUTION

[Bradley]

Bradley: I just went through the mini-itx selection process, and made these decisions:


Sandy, what motherboard did you choose.