Help an idiot out!

Cexxy · 07-19-2001, 05:16 PM

Hi there.

Big stupid questions coming up:

Ok. I'm working on my first in-car computer. I'm very new to this. I thought about building a PSU at the beginning, but since i had to ask what a diode was, i figured trying to build a power supply right now is a silly and pointless endeavor. So I'm buying one. Probably from Keypower or Arise. And yes, I'm buying one, so please just accept that and don't tell me how easy it is to build my own.

ok, so how does it hook up to the car? Splice it in after the alternator? Straight to the battery? I know that you can go either way, but what sorts of problems would i be dealing with depending on the road i take? Are there plugs or do i have to actually splice wires? I can't tell from the pictures i've seen.

What the hell is the voltage coming from the car? I thought it was DC12+ but then i heard that the car idles at ~14. And the computer uses how much? 5?

See? This is why I'm buying.

I have other questions, too!

I want to put a slot-loading cdrom in the dash and hook it to the computer as a makeshift cd player. But I don't think I'll have enough cable to reach from the computer to the drive. How long can the ribbon cable be before you start running into signal problems/degredation/crosstalk? I hear it's only about 18 inches. If that's the case, then goodbye trunk installation!

If I have a measly pentium 100 mhz right now (and I do) is it worth getting a display? I mean, what the hell could I run on a display with a p100? Probably nothing. So I don't think it's worth the whatever-hundred dollars for the screen and decoder card. But I still want one.

Control issues?

I was thinking about that lcd 'game controller' device that i saw. That would allow me to toss out my video card. But I'm not sure if the screen works like I'm imagining.

What happens when you set winamp as shell in Win9x? What's it look like/Do? does it just load winamp and give it focus? does nothing else load?

and how should i deal with the shutdown issues? I heard that 'Write behind Caching' is what's responsible for the hard-drive raping that happens when you power off without a shutdown. If i turned this off would that fix anything? would it make things worse?

ok sorry. this post is out of control.

thanks.

jshrieve · 07-19-2001, 05:39 PM

Quote:

ok, so how does it hook up to the car? Splice it in after the alternator? Straight to the battery? I know that you can go either way, but what sorts of problems would i be dealing with depending on the road i take? Are there plugs or do i have to actually splice wires? I can't tell from the pictures i've seen.

Two options. Run a wire directly from the positive terminal of the battery (use a ring terminal to put it on the battery post) to the positive terminal on the PS. Run a wire from the negative terminal of the PS to a bare metal piece of the chassis. It can't be painted over, it has to be bare metal.

Other option is to instead hook up the positive cable to another pre-wired source, like the cigarette lighter or radio circuit. Depending on your car, those may or may not be appropriate for your situation.

Quote:

What the hell is the voltage coming from the car? I thought it was DC12+ but then i heard that the car idles at ~14. And the computer uses how much? 5?

Car batteries are 12V. The alternator produces 14V-15V usually. It needs a greater voltage than the battery in order to charge it. The exact voltage will vary slightly depending on your load and your engine RPM. When cranking the engine, the voltage can dip down low (like 9V).

A computer doesn't "consume" voltage. An Arise or Keypower DC-DC PS will run off something like 10-18V. Any of those voltages are okay. The amount of current the power supply uses is measured in amps. The amount of power is measured in watts. (volts * amps = watts).

BTW, when you wire up the cable for the computer, you need to make sure the wires are thick enough to carry the current. There are wiring guides on the net which will tell you how thick a cable you need for X current over Y distance. If you go too small, you'll get less current and voltage and more resistance. If you go too small, the wire could catch on fire.

Quote:

put a slot-loading cdrom in the dash and hook it to the computer as a makeshift cd player.

Don't waste your time. Not only will you not be able to run the cable that long and maintain signal integrity, but PC CDROM drives are not made to handle the vibrations and shocks of a car. It'll be skip skip skip skip skip skip. Stop using CDs, use mp3s. If someone brings a CD, you can pop it into your computer in the trunk while parked and rip the CD to mp3, then listen to the mp3s.

Quote:

If I have a measly pentium 100 mhz right now (and I do) is it worth getting a display? I mean, what the hell could I run on a display with a p100? Probably nothing. So I don't think it's worth the whatever-hundred dollars for the screen and decoder card. But I still want one.

A P100 will probably just barely play MP3s. I'd probably go with a linux or DOS setup, to cut down on the OS overhead, since you won't be doing anything other than playing MP3s. I wouldn't bother with a display anyway. You could wire up a character LCD to provide info on the mp3s you playing, provide simple menus, etc.

Quote:

and how should i deal with the shutdown issues? I heard that 'Write behind Caching' is what's responsible for the hard-drive raping that happens when you power off without a shutdown. If i turned this off would that fix anything? would it make things worse?

If you go with a DOS player you won't have to worry. If you go with linux, use a reiserfs filesystem and then you don't have to worry. If you use Windows, most people just don't worry at all, or they buy/build a shutdown controller to nicely shutdown their system without them. I'm pretty sure most just turn off the system without warning and a scandisk once a blue moon.

I strongly suggest reading back through the achives and doing searches on questions you have and topics you're interested in. Most of this has been answered many times.

[ 07-19-2001: Message edited by: jshrieve ]

darkwingduck · 07-19-2001, 05:50 PM

ah, well the first answer would be search the other posts

but im in a good mood today so here goes

Your car will supply you with power from 10 to 18 volts depending on if its running, being cranked etc. When you crank your engine the voltage will drop. And you may get power spikes up to 18 volts

Your computer runs of 12+, 5+ and 12- and 5-
Please obeserve that - is NOT ground its a power reference thingy (i cant explain it sorry)

As far as i know the arise power supply will provide all the power you need, as for the wiring, someone with an arise powersupply will have to answer, but the general answer will be just like you would to your normal ac-dc power supply, you just feed it the power from your car and not 120/220 volts ac

Buying in this case is considered wise, Cenwesi just rambled one about people knowing their limits, hehe

The cable lenght is a bit more touchy, i belive that the general opinion is somewhere in the 6-9 feet region, anyone ??
Some people has spliced cat 5 cables (network cables) because they are shielded and therefore less sensitive to interference. Extending beyond the 6-9 feet (if that is the max) will create problems with the timing.

As for the minimum requirements the jury is still voting

My personal opinion is that a 100 mhz Pent will do in does and may just be able to handle win95. I'm personally running a 166 nonmmx pent in win95 2'ed, and it does just fine, i would however not rely on a much smaller processor in a windows environtment
It will do films of a decent quality (can just about pull asf movies that are about 200 mgs for a 1.5 hour movie.

I have tried a divx movie, a slideshow would have been embarrased

As for display are you talking tft or characterbased ??

If you spend 200USD+ (tft-lcd) then you might want to spend more on your processor as well

You can get NSTC/PAL displays for about 150USD but you will need a graphics card with a tv-out. They are generally a bit less clear but somewhat cheaper (i use a 5.8" PAL screen and it works like a charm)

I cant remember the price of a decent character based lcd but i belive they run about 50 USD rigged ( cables attached for you, and about 20USD for the character display alone ( typically a 4x20 or 4x40) ie 4 lines of 20 chars.

I do recommend a display of some kind, it eases the use of the system, but there are a few that run their system, purely by input.

The shutdown part is quite funny to, we are some that just powers windows down, me Cenwesi i belive does the same alon with several others. It doesnt hurt your harddrive in any way, just remember to disable scandisk check on startup with a tweak program (cant remember which one i used).

There are some that dislikes the thought of just powering their system down, they usually by a shutdown device that will shutdown windows in the "correct" fashion, searh for shutdown devices ..

Glad to help

darkwingduck · 07-19-2001, 05:51 PM

damn i took to long writing this down jshrieve beat me a the finish line

magnetik · 07-19-2001, 06:28 PM

As far as a W98 shutdown goes.... just run the "msconfig" utility that comes with Windows 98 to disable scandisk on startup. I also have my virtual memory disabled, so no swap file is used at all avoiding further writebacks to the harddisc too - you need a fair amount of memory for this to work well though (> 32MB). Once this is done, just shutdown anytime by dropping the power to the PC.... hasn't failed yet and the hard drive is still bad cluster/sector free!

Like darkwingduck said there are other utilities for turning off scandisk which you will need if you run a W95 OS (the msconfig util didnt make it into 95). Also consider running 98lite for a more stable OS.

RaZor · 07-19-2001, 07:29 PM

you can do some tweaking by visiting regedit.com they show how to disable certain things for all OSes and they tell you what it will do for your system.

Cexxy · 07-20-2001, 10:11 AM

Thanks for the help guys. I really appreciate it.

I guess you're right that it would make more sense to just rip the songs from the cdrom instead of play-skip-ing them-skip-str-skip-aight from it-skip-. But still, it would be nice to have a cdrom available up front where, at the very least, the passenger can get to it. It's not very convenient on long car trips to pull over to rip cd's from the trunk.

I'm SERIOUSLY considering getting a better proc/mobo. Anyone know of a decently cheap one with GOOD integrated sound? I was thinking about waiting for the nForce to come out, but that won't be for at least another month, and they're probably going to be too expensive to justify sticking it in my car. I was thinking a celeron-based system, probably.

I don't like the character-based displays very much. If I have a computer in my car there's no way i can limit what it can do by not giving it a real display. Hell, if i have a celeron in there, games ARE going on it. Even if i never get to play them. You can't ignore your roots.

I saw something besides a TFT. Started with an s maybe? Andyone know? What's the difference? Are they just talking about laptop-like lcd's versus character based displays?

If you have any other advice, lay it on me.

Cexxy · 07-20-2001, 12:23 PM

ARRGH!

STUPID NETWORK!!

Ok..I'll write this all AGAIN!

GRR.

ok...I think i'm going to update my system to an Athlon/Duron based system. I found a motherboard that has integrated everything ( the MS-6738 ). And it's also a MictoATX form factor, which means I could stick it under my car seat. And there's no PCI cards to deal with, either, because it's integrated everything (video, sound, LAN). Now, i know that integrated stuff is typically not as good as add in cards, but all i really need this thing to do is play mp3's. I'll worry about 3D performance later, i guess.

I'm really most focusing on the integrated lan and sound. The video is a nice extra, even if it is crappy.

Does anyone have anything to say about this motherboard or other motherboards by MSI? How good is the integrated sound? How many channels/voices can it support? I don't care about 3D sound or anything like that, I just want it to play music and wav files and things without sounding like a bunch of caca.

Know of any other MicroATX mobos that aren't pieces of garbage?

magnetik · 07-20-2001, 07:29 PM

Quote:

Originally posted by Cexxy:
<STRONG>Know of any other MicroATX mobos that aren't pieces of garbage?</STRONG>

its really a case of trial and error..... but in my experences sadly the good-old plugin sound cards (creative labs) a usually of a better standard. I do know that a few mobo makers used a Vibra 128 chipset on-board, maybe looking for one of those would be a good bet.....

the athalon/duron is a good choice too.... great bang for buck at the moment....

jshrieve · 07-21-2001, 08:01 PM

I suggest getting an MSI-6215 computer. It has tv-out which you can use to drive a display, and it has two PCI slots. You may not use those PCI slots now, but if your tv-out or sound-out should ever go bad (tv-out going away has happened to a number of people on different brand tv-outs), then you can get a pci card tv-out to replace it, instead of buying a whole nother machine.

As for keep pulling over by the side of the road on a long road trip to rip MP3s, why would you need to? Rip all your CDs to mp3s *before* the trip. Then you won't need your silly CDs during the trip. Get your friends to temporarily give you the CDs they'll want to listen to in advance. Or rip them while you stop once for a snack break, then pack those CDs away. =P

There's no reason you should need to "keep pulling over".

PaulzY · 07-22-2001, 12:35 AM

athalons and durons are power hungry its ok i suppose but if you forget to turn it off i will run down battery quicker not best suited for car. id say stick with celeron and get a decoder card with tv out for tft if you going down that way, but i think you undrsitmateb how nice a character display looks for playing mp3's

Cexxy · 07-22-2001, 03:45 AM

It's not that i'm underestimating character displays, it's just that I want to be able to use the computer for other things besides mp3's.

And i already ordered an athlon-based mobo. Although i might return it for that MSI computer. That thing looks pretty sweet.

magnetik · 07-22-2001, 04:02 AM

Quote:

Originally posted by PaulzY:
<STRONG>athalons and durons are power hungry its ok i suppose but if you forget to turn it off i will run down battery quicker not best suited for car. id say stick with celeron and get a decoder card with tv out for tft if you going down that way, but i think you undrsitmateb how nice a character display looks for playing mp3's</STRONG>

Athalons and durons power hungry? so are Celerons.... I spose all CPU's work hard and generate a nice amount of heat. But going for a celeron over a duron I don't think there is a reason for either way, apart from the difference in costing...

I do agree with your character LCD statement tho! Unless of course you want DivX/DVD/etc I think its overkill for just mp3's....

Cexxy · 07-22-2001, 04:07 AM

well, i wasn't planning on hooking it straight to my battery, just because i'm dumb and would probbaly leave it running and leave myself stranded someplace.

I know me.

wizardPC · 07-22-2001, 09:47 AM

I've always heard that celerons are low-power, low-heat (thats why my old celeron is still working after 18mos with no heatsink) and all AMD chips create excessive heat due to their high power comsumption. Isn't it recommended that an AMD system (athlon or duron) use an approved 300 watt supply? I only had a 160watt on my celeron