hey guys,
i know that you will probably say wrong area, but there are some guys here that i never seen in the audio + electronics forum.

now heres the deal, im just waiting on a lcd (trying to mod a 10.4" laptop LCD) and im going to put a computer in my car for the usual, now the thing is, everyone always goes car 12v -> DC/AC converter -> computer powersupply -> mobo and drives.

now ive been thinking, why use the converter? ive got that we used for a TV on trips to whistler but i just dont think its that great to do all that converting. so heres my idea, what if i just took my cars power and used it for the computer? i know that it varies around 12v so it should work, but the computer doesnt have a high tolerance for fluxuations so im wondering if you guys with electrical engineering degrees and stuff can help me on this one.
what kind of filters or something would i need inorder to get alittle cleaner power to the parts? also where would i get them? and is there anything else I may need.

it could just hook right up as it is, but i dont feel confortable feeding a powerline that fluxuates so much to the parts.
thanks guys
MrGone

 

i don't have my EE degree...yet, but i don't think you wanna do that. it looks like you said you have the inverter already, so i think you wanna use that. also, where are you gonna put the 10.4? is it gonna be flush. cause i plan to do the same thing soon, and i haven't measured yet, but i wanna use something around 10.4 or probably a little smaller to get it into the dash flushly. anyway, good luck with your project. let us know how it turns out, and i hope someone else can clear up the inverter thing better.

 

hmm
i was planning on somehow having the screen slide out down or something like that. its alittle to big to be built in and have a deck and temp controls etc.
I think i need a controller for the lcd, but im wondering if there is a way to take a piece off the laptops board or something, i dont want to spend 150 on a controller.

also i noticed you said you dont have your E.E. degree YET, so do you have any ideas or suggestions? btw, what all does a E.E. degree cover? sounds interesting.
ill keep you posted but this project isnt so high up on the priority list mainly because of that LCD.
later
MrGone

 

Devices that are designed to operate on AC have transformers in them. Without a short lesson in how motors work, an AC (alternating current) signal oscillates between negative and positive; the transition from -ve to +ve causes a motor to move. The motion of the motor is what produces a constant signal fixed at some level determined by the coil ratio of the transformer (motor-->conductive metal with wire wound around it).

You cannot take a DC signal and feed it into the AC power input. While you may not damage anything, you won't be able to turn anything on. However, if you can take a DC signal equivalent to what comes out of the transformer, you CAN connect it to the point in the power supply circuitry that accepts the transformed signal. In short, use your unconverted DC signal but do not feed into the AC power input.

Then you have to make sure you have enough wattage (enough current vs voltage).

Do you have something against converters? Why risk damaging the circuit board on the monitor just in the name of saving a few dollars? I say get the converter.

 

i'm sorry, by YET, i meant that i just graduated high school a month ago, and as of now, EE is my major. I'm taking a class come august which is basically an intro for all engineering to see if that's what i want. and basically what frankbattle said, you can't use the battery directly to the computer power supply.
do you actually have the screen yet? cause i'm looking at flat-panel.com right now. they seem to have a good selection at decent prices and it says you can customize your screen, so when i find the perfect size, i could have them make me that size possibly. i'm thinking of getting touch screen also to solve the mouse problem i was trying to figure out. right now, the multimedia system i'm planning is high on my list, but no budget well i hope things come along with your project (and mine) and i hope the link might help. good luck.

 

Frank Battle -thank you for that idea of connecting a 12v line to the power supply, that would probably keep the power more consistant right?

however im sorry i confused you guys, incase you didnt know, computer componets run at 12v, so i was just thinking about leaving out the power supply and just hooking them directly, but i just wanted to know if there is something i can do that would balance out the current to 12volts or atleast make it not fluxuate as much.
does that make sense?
thanks
MrGone

(i just got an idea, again, no knowledge but hey... is there a way to use capacitors to help balance out the load? i know that there are a few in the power supply itself and all over the mobo. hmmm

 

It's okay to run directly off the cars 12V power supply. Even though it will run at 14.4V not 12V, this is a tolerable amount that the computer's power supply can handle. If you want to filter out noise you can use a choke (an inductor) in series with the +12V line (or even both). Another thing to prevent voltage spikes would be to use a 16V Power Diode, this would connect across the pos and neg cable (in parallel), the spike would then act as a shunt and shoot any spikes to ground. It is important to connect the Diode in the proper direction.

If you were to reconsider the power invertor, I would reccomend useing one that produces a true sine wave. Most invertors sold are a modified sine wave, that resembles more of a square wave. This is not reccomended for sensitive components like computers. A true sine wave convertor will of course be more expensive.

 

ok,
so far i can hook up a ground and 12v to each of the pieces and install that stuff, but also how do i get a 5v supply? cause harddrives power molex connectors go {[+12v][-12v][-5v][+5v]}
where the 12v is yellow and the 5v is red with the two middle grounds are black.

also the mobo has power inputs for 3.3v, 5v, 7v, and 12v.

because your all asking about it, i have a converter, we use it with a tv and/or my dads laptop in the car but we havent used it for a while. i just would rather not have to have all the extra crap to worry about (as in the extra space needed.)

thanks guys
MrGone

 

I have been working on putting a computer in my car for the last few weeks and it isn't easy. I probably have almost 50 hours of work and I'm only about 80 percent of where I want to be. Anyway I used a 7 inch LCD that has input for RCA video. Not the best but it will work for now until I have cash to get a real computer LCD. I took out both the cup holder tray and my stero and the LCD fit almost perfectly flush with the trim. From doing my own work I'm not sure if you are going to be able to fit a 10.4 but more power to you if you can figure it out.

As for power resources the easiest is to go with a power invertor. Of course the problem with that is it isn't easy to use Suspend To Ram (STR) which will provide the fastest boot time. (Assuming your using an ATX computer and not AT) Each time you turn off the car you have to either turn off the computer or hibrenate it. Also by using the power invertor method (which it sounds like you probably won't) there is also something called "power good". This is a signal that ATX (maybe AT to.) power supplies send to the motherboard to signal that the power supply is feeding clean power. If the signal isn't sent then the motherboard will not post but your harddrive's and fans will power on. If you come up with this problem and the computer won't boot then resetting the computer should allow it to boot. There is a way to fix this by tricking the motherboard by supplying the signal it is looking for but I don't know those details as I am currently looking into it.

There is also the option of going the DC-DC route which is really expensive but really the best. There are places to buy DC-DC power supplies or even plans to make your own. To buy I was quoted close to 200 bucks for the power supply. To build your own it probably comes out to less then 30 bucks but requires enough knowledge to solder and build circuits. Using a DC-DC power supply allows you to use STR which basicly puts the computer in a low power sleep mode but can be started in a couple of seconds. I think the power draw is low enough that you don't have to worry about it draining your battery to fast.

Another route which is where I am going, is to buy a VIA Eden board that comes with a case that already has DC-DC power supply. The Eden board is basicly a really tiny intergrated computer and includes a VIA C3 800MHZ CPU. You can buy the case and computer for less then 200 bucks at http://www.caseoutlet.com/NWPc/2677/itx2677.html#MB keep in mind though that even though the input is 12 volts it uses a wall power invertor to change 120v AC to 12 volts DC. You should be able to hook it up to the car battery by losing the wall invertor but you would want to make sure you clean up the 12v from the car before hooking the computer to it.

Have fun figuring out where to hide everything. I eventually ended up mounting the whole computer system ontop of a subwoofer box that was meant for two 8"'s. It will eat a lot of trunk space really quickly so keep that in mind. Lastly the best place to get all of this info is from http://www.mp3car.com many of you probably already know about this site.

One last thing now that I'm thinking about it. Be careful of blowing your speakers when you hook everything up to your sound card. I did this by not realizing that my amp was cranked up along with my sound settings in windows being set high. When the computer booted and the windows sound played it pretty much blew out my fronts.

Hope this helps out your quest and look forward to hearing the results.

 

Does anyone have any useful diagrams or pictures?