Thread: G4 Powerbook in VW Rabbit

power: you will need a 12v regulator-- cars voltages vary from 5-18 volts at times-- electronics don't like that much fluctuation.

i also prefer to run a new power line from the battery instead of tying into factory wire for any of my add-ons.

this has some advantages over the factory wiring-- you know exactly what is getting power from that line(in my car, some fuses are for more then they are labeled for, so the fuse rating is less then expected when i try to replace 1 factory device..) and if you do blow a fuse, you will be able to trouble shoot a little faster because you know where the wire goes, and what it powers.. and because it was added on, it should not ever affect any of the OE vehicle stuff, so you don't have to worry about messing up your car as much. you can also hide the wire pretty good, and run it anywhere you need it in the car!

for the location, i doubt that under the dash will have enough room, but if it does, it will be a very tight fit, and you will need to consider ventilation.

under the seat is a good spot, assuming that it will fit (trouble points can be the seat rails, and seat-bottom-to-floor clearance) the biggest problem here is that you need to remove the seat for servicing, and that there is a possibility that stuff might get spilled on it..

depending on the car, there are sometimes large areas behind factory panels in the trunk that can work well, or sometimes, you can mount it below the rear parcel shelf with a small amount of difficulty..

you should definitely be able to find a spot in the car that the laptop fits, and hides good in.

oh, and for wiring, check under your door sill plates-- those plastic covers at the bottom of your doors, next to the seats-- every family car i have worked on has more then enough room in there for almost any wire you need to run--and be completely hidden

for the overall setup, i am not sure how easy to use that android app is(can you operate it at 70mph with minimal distraction? not all apps take this into consideration), and for me, overall phone connectivity is sketchy, so i wouldn't want to rely on my phone connecing to my carpc.. another thing you might want to consider would be a display like this to see what is playing:
http://www.matrixorbital.com/GX-Seri..._17/index.html

the typhoon series is at your budget limit(i don't play the penny-less game ), but last i looked at these, they are supposed to have the easiest software to work with.. but there are cheaper options that can do the same thing..(just look around their site)

and if you decided to scrap the phone-control thing all together, you could use something like the griffin powermate to control the songs..

Thanks for the quick response Soundman.

If the car output fluctuates that much I'll definitely put in a voltage regulator, and under the seat looks, on first inspection, pretty good.

When you say you prefer to put in a new line to the battery, this line can still include the ignition switch? (Please excuse my ignorance. I don't know anything about how car electrical systems are organized.) For a set up with a desktop you'd need power from the battery even when the car was parked just to keep it in sleep, but I want my laptop completely separated from the car battery once I take the key out of the ignition.

The android app is connects directly with iTunes and acts basically like the media player interface you would expect on an iPod touch or any digital music player. I'm not too concerned since most of my driving is stop and go, and I usually just set my music when I pull out of my driveway or at red lights. I am figuring on the most expensive part of this project being the UI device, so I thought it was clever to spend it on something I might use outside the car too... heh. I think I'll probably spend a little more time considering UI options though.

After browsing a little more, I see a lot of people are using P1900s (or similar) as power supplies for their whole set up. If I'm powering just the laptop, the Carnetix stuff seems a little unnecessary to me. Are there people out there just building a simple regulator circuit using an inexpensive 12V regulator IC? The laptop takes up to 45W, so I think it shouldn't draw more than ~4 amps. I'm looking at some LT108* 12V regulators, max current 3 A/5 A/7.5 A options, and input range up to 25 V. Maybe this is what Soundman was talking about above...



I'm thinking it might be about time I dive into my car and actually try to understand how the current electronics are powered to shed some light on this.

EDIT: Nevermind. I just rediscovered the FAQ emporium.

Don't use linear regulators. Get the P1900 and be done with it. Spend $95 bucks to save yourself the cost of a laptop. Alternatively, you can use a cigarette lighter power adaptor.

Unless you know PRECISELY what you are doing, rolling your own power solution is more trouble than it is worth.

Never skimp on RAM, HDD space, or power supply technology. At least that's my big 3 rules.

Talked to a cousin of mine today, who's an EE, and he agrees with you Bugbyte. He said he was sure it would work if set up properly but it was a good way to make my laptop explode. As exciting as that sounds, I think I'll follow your advice.

So I guess I'm looking at the P1900 or the DC adaptor. I'll take a second look in the laptop power subforum on these options... P1900 seems to have a cleaner voltage regulation albeit at a higher premium. I don't need anything to turn the powerbook on and off since I've set it up already to wake up upon receiving power and go to sleep immediately when power is switched off, so I'm not sure it's worth it. Time for a little more reading.

Also, was toying around with a friends Android phone as a controller and I discovered Android doesn't support ad hoc computer networks out of box. This means either modifying the software on the phone (has been done and documented on the web), or using a different device as a controller e.g. iPod touch as a remote in a similar fashion as I proposed with an Android phone or some other usb peripheral in some other fashion. Still trying to keep this a budget build so I'd like to use things I already have or I'm getting anyway.

the new line i recommended to run from the battery would be a constant-on line-- there would always be voltage on the line, unless the fuse was blown/removed(the one you should place near the battery )..

the carnetix, and other power supplies use a switched line from the ignition switch--this line only supplies 12v when the ignition is at the 'acc', or 'on' position(it is dead at the 'off' and 'start' postions).

all power supplies that are offered for carpc's operate the same as car audio amps-- ie: they have a large power wire that always has 12v, a ground, and a small 12 switched line(from the acc circuit) the amps/pc power supplies will not turn on unless there is 12v on the small wire(sometimes referred to as a trigger)-- to keep the device from draining your battery when the system is off.


the amount of time that went into designing the carnetix will make it more reliable then a home-brew solution: not that i am against different ideas, i just think that the carnetix solution will have better design characteristics then a home built version(the carnetix can turn the pc on/off, regulate the voltage, or up convert it to a laptop-usable 18-20v and can survive crank--i doubt most can match that for $100)

The cigarette lighter adaptor will work just fine if you want to power only the Macbook.

The Carnetix is useful if you will need to supply other devices as well. There's plenty of extra capacity on the P1900 to provide clean 12v power to, say, a monitor or hub or whatever may need 12v power. The 1900 will take care of the issues of fluctuating voltage in that case.

In summary, if you have everything covered and simply need to power the Macbook, you can likely find a cigarette lighter adaptor that will work for less than a 1900. If you need to power anything else, the 1900 is a good choice for both the laptop and the extra devices and will provide clean, regulated power to them.

Okay. Ideally, I'll have no USB peripherals and I can't imagine using more than one, which could easily be powered through the powerbook. It sounds like the DC adaptor is more suited to what I'm looking for at the moment. If I decide to expand the project later I'll pick up a P1900 then.

Will update with whatever I end up putting in.

I appreciate the advice guys!