Instructables
An android tablet ia a logical choice for a car PC. The device offers additional features beyond regular car stereos. While many car stereos have GPS, the android device offers a more intelligent GPS. It has all of your google contacts addresses already in the GPS, it has your calendar with events and their locations, Chrome to phone can automatically send directions from your computer to your car. The device can store music, use internet radio, or play music using a cloud player such as Amazon cloud. These are features not available on even the most high end luxury cars.

I recommend choosing a tablet that already has a car dock. This dock can be easily modified to be permanently installed where a double din CD player would normally go. Also, with a car dock, the device will be easily removable so you can prevent theft and use the tablet elsewhere.

Tools:
Wire Strippers/Crimpers
Soldering Iron (Recommended)
Screw Drivers
Drill
Dremel with Cutting Blades

Equipment:
Tablet with Car Dock ( I chose Samsung Galaxy Tab 7+)
1/4" Sheet Lexan (Approx 10"x6")
Paint
1-1/4" Hole Saw
3/8" Drill Bit
Amplifier
Car Audio Adapter
Spade Plugs
Wire - Heavy Gauge to Power Amp
Wire - Medium Gauge for Speaker Signals
Grommets
Electrical Tape
Scotch Tape
 
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Step 1: The Audio

Picture of The Audio
Replacing the stock stereo unit with a android tablet requires an external amplifier for the sound to play through the speakers. I choose a 4 channel amplifier. Four channel because my car has four speakers. I have the amplifier mounted under my passengers side seat, but the amp could be mounted just about anywhere.  I chose just about the cheapest amp I could find.  I don't listen to much music, mostly audio books and podcasts, so I was not too concerned with sound quality.  I do listen to music using this amp and it sounds good enough for my ears.
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ShaQ1nJ5 days ago
Very informative article!! You answered so many random questions I've had over the years, like why does charging cause static to appear in the audio? Or how can I stop charging a device once the car is off? Thank you so much for writing such an excellent guide.
BigMaxee2 years ago
Hi Guys, I am very new to this forum and find all this discussion very interesting. I have a 7" Android device which has outlived its usefullness to my children apparently and so I thought it might be fun to rig it up in the car for playing tunes and using as a gps and reversing camera. I noticed that JFarmer had quoted some regulations including the following "(2)In this regulation “television receiving apparatus” means any cathode ray tube carried on a vehicle and on which there can be displayed an image derived from a television broadcast, a recording or a camera or computer." Now correct me if I'm wrong but I am pretty certain none of the devices any of us have or are talking about has a "cathode ray tube". Does this mean that the laws quoted by Mr JFarmer are nul and void perhaps?
Just a thought... many have gotten by on a technicality before. :)

That is basically null and void.

What most laws state these days is that video entertainment cannot be in the view of the driver while the car is running.

Video for rear view and backing up is ok though.

NaptownWicked7 months ago
Where did you find the bracket for the tablet?
hightekhick7 months ago
I started mine with a Samsung Galaxy tab 3 7". I'm doing a removable mount. And since everyone is having an issue with the whining noise, I found that using the Bluetooth function for the stereo, it doesn't create the noise. And I'll be using the ELM OBDII bluetooth adapter so I can monitor my vehicle using a split-screen app.
jbianchi38 months ago
Could you use a otg plug and dac instead of the 3.5mm and power cable?
koney10 months ago

How do you solve automatic powering ON/Off with ignition?

1st thing is setting the "Stay awake while power is connected" setting under developer options, and setting the screen timeout to a short value under display settings; if you connect the charging cable to a power source that goes on and off with the ignition, but what If the standby time of your tablet is not enough to handle your typical time with the ignition off? You may use an app like Tasker to set additional rules, like turning Wifi or cell connection off when the car's power is off. But how to solve complete On/Off ?- Something like hibernation like in Windows would be really cool - could be quite fast (tablet has a small ram) .

pm116 koney8 months ago

Hi there, i recently found a free app that as soon as you unplug the charger it automatically pause all media and navigation apps that drain the battery pf my android tablet. Its called AutoSleeper and this is the URL for Google Play.

https://play.google.com/store/apps/details?id=com....

Check out its features:

It is the best solution i've found.

  • Your Tablet goes automatically to Stand By mode when you turn off the car engine- The Song you were listening to Pauses - When you turn on the engine the Tablet goes On again without pressing the Power Button:- Your GPS is on again- Your music continues exactly where you had left it- You decide if you want your Tablet to go to Stand By mode or to Off mode - You decide within how many seconds after you turn off your engine you want your Tablet to deactivate.- Autosleeper is designed for Tablets and Smartphones

If you have any other suggestion let me know.

FranzIonut1 year ago
Some apps for my tablet while I'm using in car and o few other advices related to what i've read :
http://gizpoint.com/how-to-tablet-as-car-pc-using-tablet-for-navigationmusicvideointernet-in-car/
If you don't have a dock,you can go further and make a custom install in your dash.
JozielHi1 year ago
Can you show a link to where you got the Car Dock? I'm only finding them for the Galaxy Tab 2 7.7 (Verizon version). I need it for the regular Galaxy Tab 2 7.0. Great job btw.
Sassah1221 year ago
This is good for people who have a lot of time and money on their hands. I did a very simple thing.
1. Get iPhone of android windscreen mount.

2. Use a standard audio cable to transfer audio signals from phone to car. I used aux port but you could also use a special cassette tape that provides a 3.5 mm jack.

3. Connect the phone's usb car charger to my 12 volt output.

4. Download apps and enjoy!
primo71 year ago
Great idea but has one flaw. There is no android software. In my car I have carpc with software Centrafuse. Centrafuse have handsfree phone option when I make the call or recive the call the music mute
and when I use integrate navigation (Garmin) that when spoken instructions the music mute. It would be great if it would be possible in Android phones and tablets.
assman661 year ago
Nice write up. Working on my own because i came across this one. One question, how are you using the 4 channels out if the amp has 4 channel inputs? from the looks of it you have 2 channels going in(the 2 rca) to 4 channels out(4 speakers). I have installed amps before but am i missing something here, don't you need 4 channels in to get the 4 channels out?

thanks in advance
hamsammy2 years ago
Great write up! I'm running into the same issue with a build of mine for an ipod cable which goes from dock 30 pin to USB for charging and 1/8" for audio. The audio sounds great until I plug the power portion in and then, NOISE! I haven't been able to figure it out but suspect it's just poor quality shielding within the cable since it's getting clean power from a computer PSU. Did you ever figure yours out?
willyam111 (author)  hamsammy2 years ago
I would try adding a ground loop isolator into the circuit.
lkatrencik2 years ago
if you don't have enought room for dock connector you can make your own http://forum.xda-developers.com/showpost.php?p=20710266&postcount=14

(samsung)
amarshall92 years ago
I never thought about using a tablet for a radio. I rather listen to my android tablet then listen to the radio because the radio plays garbage repeatably.   Does it work wireless like some obd II systems.
Now if only there where an app that let you use an Android tablet as a speaker phone unit for a Bluetooth enabled cell phone.
orbit12122 years ago
Hey you should definitely make a series of videos on this this is amazing and i will be doing it in my car.../// i want to also integrate some engine stuff such as speed, rpms, if the tablet can read it i want to see if it can google maps integration as well just some ideas
willyam111 (author)  orbit12122 years ago
The Tekzilla recently did a show segment on a cheap bluetooth obdii reader that can transmit to a tablet running Torque to give you those engine parameters. Here is the bluetooth module. I personally have never used it so I can't speak to how well it works but they seemed to like it.

http://www.amazon.com/Soliport-Bluetooth-OBDII-Diagnostic-Scanner/dp/B004KL0I9I/ref=pd_sxp_grid_pt_0_0
lordvellos2 years ago
Just out of curiosity, but since android is an "open" platform, are there in the market apps or hack that it could trully be converted to the central of the car, attaching it to different sensors to get temperatures, rpm and all other kind of stuff?
Yes you can, and it is a shame that the author did not delve into a vehicle data interface (OBD II). The android market has a host of apps that read in important vehicle data from an OBD-II interface.

You see, all cars from 1996 and later have a standard port underneath the driver's dash that allows for auto shops to run diagnostics on cars and to even set some variables. One of these variables is the state of the "engine light", which is how shops tun it off when their work is complete. Other information available ranges from fuel consumption to o2 sensor readings, practically all of the data that the car's computer has on hand, including those that you mentioned. Sadly, one of thee ones commonly missing is oil pressure.

Anyways, this port can be connected to by an aftermarket reader that uses a decoding chip (one of the most popular is called "ELM 327"). This reader may be connected to your android, ios, or other device, granted that it has the software to read the incoming data. There are many bits of software out there for reading OBD data, my favorite is "Torque" on the android market.

As for connectivity, you could use tethered or wireless. Wireless would be in the form of a wifi hotspot connection or a bluetooth connection. I curently use a wifi OBD-II adapter in my own car with the Torque application. This adapter only cost $25 on Amazon and seems to work perfectly for me (though there seem to be many cheap brand versions that do not work well). I believe that Android supports all communication formats, while iOS devices do not support the data transfer channels in a bluetooth connection.

There's a lot of info that I have not put in here, but I hope this answers your questions. On a side note, my car did not come with an mpg calculator, but Torque works wonderfully at calculating instantaneous, average, and trip mpg.
Fichtenelch2 years ago
And don't forget to install a fuse within the first 30cm of wire from the battery! This is very important to protect the wire and the car.
bdore2 years ago
You could add the 12v power socket with an inline fuse to the remote (power antenna) wire from the wiring harness you bought. That would make things simpler and would not require cutting any stock wires.
johnvillar2 years ago
Didn't know about this ground loop isolator... now i know why i get a lot of static on my rig. Thanks pal.
Static or alternator whine? Usually in cars it's a whine that changes pitch with the speed of the engine.
Definitively whine (mistook the sound for plain static)... its pitch gets louder as i accelerate, so i guess it's because of the alternator spinning more rapidly...
Check your grounds, and check for a fried channel on your amp, happened to my first amp thanks to me dropping it to like 1ohm before I even knew what ohms were, lol.
WolfTohsaka2 years ago
Great instructable !

Just one thingie... when replacing the car stereo, you use a harness to connect to the speakers... why not use a harness to get the (fused) stereo's 12v to power the amp and tablet ?

Kevin
willyam111 (author)  WolfTohsaka2 years ago
jdonor got it right. The amp draws a lot of current and you need very thick gauge wire to power it. Connecting to the battery is the best way to do this. Don't forget the inline fuse holder when powering the amp. And be sure to read the instruction manual that came with you amplifier or get it professionally installed if this part scares you.
The harness adapter should power the Tab, and you are right about the amp.
Having done some car audio mods before, I can tell you that's a bad idea. The problem is the available current due to the wire gauge. The wiring in the car is going to be around 22 gauge, whereas an amp needs something around 8 (at least the ones I've seen). As a cautionary tale: I got a cheap kit to wire my first amp that came with 12 gauge wire for the power, and my amp was fried in a day. I mean: toast. Talked to the experts and they said I needed a bigger gauge. Moved to 8 gauge with the replacement amp and I haven't had a problem since. So you'll definitely want to read the manual for your amplifier, find out what gauge wire you need and power it straight from the battery. Hope that clears it up!
If you replace a stock head unit with something like 4x25RMS AB class, you need a 4x25RMS AB class amp to use "dashboard gauge". Anything above stock will require power from battery... granted. BUT, you need a relay using the after-contact from your car stereo if you don't want to let the amp powered when the car has shut down.
baldmosher2 years ago
If by 'noise' you mean electrical interference, have you tried a ferrite loop in the cable to see if that helps? (It might not)
Good idea.
Kiteman2 years ago
This is a cool project, but readers ought to be aware that it is probably illegal in the UK, since it is not a dedicated satnav or music player.

You can get round it by wiring it in so that it cannot function whilst the engine is running.
Figures.
Great project - although there are plenty of bluetooth enabled after market systems available - which could make the audio linking aspect a bit easier.

Saw this regarding legaility in the UK...
http://www.in-carpc.co.uk/legislation.htm
"
Ensuring that the driver is not distracted

Section 109 of the Road Traffic Construction and Use Regulations clearly states what information can legally be displayed on a screen that is within the driver’s field of vision in a moving vehicle. All our fully installed systems apart from the Basic and Lite packages include the Centrafuse software interface, which provides a touchscreen friendly user interface. Centrafuse comprises many modules that perform different functions, examples of which are the navigation module, the hands-free phone module and the DVD player. When the vehicle starts moving, any modules that could cause distracting or illegal information to be displayed on the driver’s screen are automatically disabled. Using the examples above, the DVD module would be disabled but the navigation and hands-free modules would not, as these are both legitimate uses of a driver-visible display.

In addition, Centrafuse is automatically activated whenever the vehicle starts moving, so that it completely blocks the Windows desktop and any other running programs, and can only be minimised again when the vehicle is stationary.

For fully installed systems that do not include Centrafuse we can use other means to ensure that the system remains completely legal.

"

So it looks like centrafuse could be your friend here ... see http://www.centrafuse.com ... and they have a bunch of apps already available to look at car diagnostics etc

This is the law
"
109.—(1) No person shall drive, or cause or permit to be driven, a motor vehicle on a road, if the driver is in such a position as to be able to see, whether directly or by reflection, a television receiving apparatus or other cinematographic apparatus used to display anything other than information—

(a)
about the state of the vehicle or its equipment;

(b)
about the location of the vehicle and the road on which it is located;

(c)
to assist the driver to see the road adjacent to the vehicle; or

(d)
to assist the driver to reach his destination.

(2) In this regulation “television receiving apparatus” means any cathode ray tube carried on a vehicle and on which there can be displayed an image derived from a television broadcast, a recording or a camera or computer.
"

Which means that you could not use it to change your music selection while driving ... but you can use it for a sat nav and to show images from a rear view camera
beehard442 years ago
Have you tried using a capacitor connected parallel to the + and - of the tablet's 5v in? a 1000uF capacitor should do the trick, the value isn't critical
also you could do the same to the amp but use a higher value capacitor, like 5000uF? Again, it's not critical
also, use shielded wire for any audio signals
willyam111 (author)  beehard442 years ago
What are you recommending these capacitors for? To reduce noise? The ground loop isolator works well to reduce any noise problems except when I tried that cable in the last step. However, that cable had the power and audio cables running right next to each other with very thin gauge wire. It was the only cable for my tablet I could find like that and was not made by Samsung. If you are saying that the capacitors will reduce the noise with that cable I could give it a try.
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