Tablet & TV Soundbar Vehicle Retrofit: No Vehicle Rewiring Required.

Welcome reader to another of my 'Build in a Day' Instructables, although technically there is not much building or making here, it's more about assembly although there is a little making involved.

The Project:

So what is this project... it's fitting a standard Android tablet into a car along with a TV soundbar and making a convenient and safe to use touchscreen interface. This is for older vehicles that do not have built-in screens, Bluetooth or AUX/USB inputs. Fitting a tablet into a vehicle is not a new thing and has been done before, but they usually require removing parts of the dashboard, adding additional equipment like amps or splitters, breaking into the vehicles existing wiring, and sometimes making some kind of holder to fit to the dash. This technique leaves the vehicles original equipment and wiring in tack and functional while having the addition of a pretty decent, easy to use setup that sounds good.

The Inspiration:

I recently picked up a used Toyota Yaris which is a few years old, and have added equipment such as cameras, power inputs and more. The factory radio/CD stereo system works perfectly well but no Bluetooth or AUX/USB inputs. I wanted to add the ability to play my own audio library which would sound good, easy to navigate to, and to not loose any of the cars information readouts that are viewed through the stereos LCD display. I also did not want to mess with the cars original equipment as having the original radio is great for short trips, and keeping the original equipment is also a plus for resale. There are other options I could have used, but this works for me, simple, cost effective, works really well and sounds really good. See Step 1: Design for more details.

Why I Like This Setup:

"A TV soundbar in a car?" Yep, and it actually sound really good, better than I expected in fact. The custom UI on the tablet I designed to be easy to see and use while on the road, and have a layout that works for me. I still retain all of the function of the cars original equipment and access to the data readouts like MPG, fuel range etc. and for security, the tablet is easily removed and the soundbar is hidden. And using the tablet is a much more comfortable and safer experience than using the smaller screen on a phone. More details on this can be found in Step 1: Design.

1. An Android tablet (choose screen size that works well for you and your car)
2. 12 volt to 240 volt (or 110 volt if in the US) inverter
3. A good quality soundbar
4. Tablet holder (the one I use works well in my car, but check for a holder that will work well for you)
5. Zipties
6. Some 3M double sided VHB (Very High Bond) foam tape
7. Total Launcher app for the user interface
8. OPTIONAL: The Android app Tasker if you want on-screen volume control
9. OPTIONAL: Memory card to store your audio content on if you tablet uses storage cards
10. OPTIONAL: Your phone to use as a Wi-Fi hotspot, mobile hotspot dongle or use a cellular enabled tablet.

Additional:

1. Just in case the inverter cable is not long enough, you may also need a pair of wire cutters/strippers, some 12v wire and some wire joiners just in case you need to extend the 12v cable from the inverter to the inverter 12v plug (a car cigarette lighter extension cable is also an option).

List Of The Following Steps:

1. Step 1: Design
2. Step 2: Set Up the User Interface
3. Step 3: Fitting the Tablet
4. Step 4: Fitting the Soundbar and Inverter
5. Step 5: Setup and Use

So Why This Technique?

1. The principle of this is nothing new to be sure, but the way I have done it doesn't require tearing apart half of the dashboard, no messing with the original vehicle equipment or wiring, having a convenient and save way to operate it, quick, it's relatively simple and cost effective to do, and ending up with a pretty decent sounding sound system.
2. Putting a tablet into a car has been done before and for the most part these involve some sort of modification to the vehicle, but bear with me as this is a much simpler way of improving the vehicles sound system while leaving the vehicle in its original condition. Sure, there are Android units available, but this means removing some of the dashboard, removing the original entertainment/infotainment system, installing a new wiring harness adapter (sometimes requiring modification) and purchasing a new dashboard faceplate. Then there is the issue of the new Android head unit, budget ones tent to crash or become sluggish to use, while better performing ones are expensive.

Why I use it:

1. Another issue is that some Android head units require removing heater controls etc. and then these controls are then all then done by the head unit touchscreen. But if the unit was to slow down, freeze or crash, then you loose that vehicle equipment control... not a situation you want to be in while you're driving. Then there is another issue which is one of the main reasons I did this install the way I did... on a factory fitted system you may have access to information such as fuel range, full consumption, and other important and useful data, but installing a new Android unit or any other stereo system sometimes means loosing access to that data.
2. As an example, apart from the fuel gauge, I like to use the fuel range data that tells me roughly how many miles of fuel I have left and the MPG data to check my fuel usage. Installing a new after-market unit would mean loosing this data. There are also options of installing a Bluetooth adapter, but again requires some kind of wiring modification and equipment removal to fit it if the vehicle doesn't have USB or AUX inputs, and these don't always work in some makes and models of vehicle. I have tried FM transmitters as well, but I simply don't like them as they are unreliable and found that the sound quality is poor.

The Setup:

1. This project uses an inexpensive 8" Android tablet, a TV soundbar with Bluetooth, a 12v to 240v inverter (240v as I live in the U.K), and a custom user interface that is designed to be easy to see, easy to use and be safe while using it. True audiophiles will probably be saying a TV soundbar is not designed to be used in a vehicle, and they would be correct, but the fact is it works, and it works really well. Sure I could use a Bluetooth speaker and have done in the past, and using direct 12v would be more efficient, But the soundbar has more a immersive sound, they generally have a choice of EQ settings, has better quality sound at higher volume, no worries about charging the rechargeable BT speaker battery, or having to reach over to turn the BT speaker power on (if it has no remote control). With the inverter connected to the cars 12v power socket, I turn the key (or push the starter button) and the speaker turns on. And with some soundbars, you also have the option to add an additional subwoofer.
2. The custom UI for the tablet not only means you can have some fun with the design, but it also gives you the option to add what you want to the screen and make the size of the buttons large enough so they are easy and safe to use, much better than trying to tap buttons on a phone screen fixed to a phone holder.
3. You also have the option to add some audio feedback when a button is tapped because of the loss of tactile feedback from a physical switch, and this makes for a good safety feature so you know the button has been tapped while keeping your eyes on the road more. And having a larger screen than say, a phone, also has another safety aspect of being able to have a quick glance of the screen to see any information compared to trying to focus on a smaller phone screen.
4. For connectivity, you can use your phone as a Wi-Fi hotspot and tether the tablet to it for internet access, great for online radio, and maps/navigation.

Additional:

1. There are a lot of budget soundbars that actually sound pretty good, some of which run off Ac to DC 12v adapters/wall warts that can be run off a 12v vehicle battery (mainly made for campervans and motorhomes), but these are a little more expensive. The soundbars come in different sizes and can be mounted on vehicle rear shelves not taking up a lot of space and can also be mounted where they are hidden (depending on the vehicle design).
2. Not an audio thing, but another advantage of the tablet is you can use it to show vehicle diagnostics using a Bluetooth or Wi-Fi OBD2 scanner. Just don't leave the OBD2 dongle permanently plugged into the vehicle as this can damage the vehicles computer modules. I have been working on cars and vans for the best part of 30 years, so trust me, I have seen this happen on peoples vehicles.

Disclamer: The mounting of the tablet is dependent on the design of the vehicle, but there is normally somewhere it can be mounted. For my car, there are three mounting points that holds the tablet well, two where the tablet holder can slide in between the plastic dashboard trim joins, and with the holder I use, it can also slot into the CD slot in the original car stereo. The place where I use mine doesn't cover any of the cars controls, it's easily viewable and easy to to use.

To start off, we will look at how I made the UI for the tablet. I wanted to make a simple design and not clutter up the screen with things I wouldn't use while driving. I used my laptop to draw up a simple design, and used the Android app 'Total Launcher' to make a functional UI. The app is a customisable launcher for phones and tablets, and you can choose to use it as a default launcher, or as a stand-alone app. The following is assuming that you have Total Launcher and a media player app installed and set up.

Drawing the UI:

1. First we need to make the design. Take a screen shot of you tablets screen and send it to your PC. We use this to make the UI the correct size for the tablet.
2. Open up a draw/paint program and open/insert the screen shot. Use the 'Crop' tool if needed so all that is on the drawing area is the screen shot.
3. Fill the screen shot with a solid colour (I used black), then draw your design. I started with the outlines then added buttons, leaving space to add the media controller and any other widgets I wanted.
4. When you're finished, save it and send it to the tablet.

Setting Up The UI:

1. Open Total Launcher then press and hold on an empty space until the page shrinks down. Click on 'Edit Off' to toggle it On. Press and hold on all of the default elements on the screen and tap the delete bin icon to start with a blank canvas. Swipe across the screen to the other pages and do the same.
2. Press and hold on an empty space until the page shrinks down and while at this stage click on the middle square icon (looks like a little mountain) and click on the landscape image. Click on 'Colour' and then choose black with the transparency slider on the bottom of the slider bar.
3. Click on the blank picture then select 'Stretch to fit screen' then name it "Home" or whatever you want. To add a second page to add more apps etc., swipe across the screen, make a new page, name it 'Page 2' and again set the landscape background to the colour black. Then click on it to bring the screen forward.
4. Click on the top right Plus icon, select 'Graphic' > 'Text' > 'Default' then drag it over to one of your background buttons you made. Resize it to fit over your button the click the cog icon at the top of the screen. Here you can name it to the app of your choice, change typeface, text colour and size, and more, then finish off by saving your changes.
5. Now click on the Play icon. Here you click on 'Action' and then 'Application' and choose the app you want the button to open such as maps etc. This is also where you can add audio feedback so when you tap a button a sound of your choice will be heard. download of file transfer some sound effects to the tablet, then tap on 'Sound' then the plus icon. Choose the sound effect saved on your tablet, then find and tap on it again, then het the back button a couple of times to exit the editor. Now when you press that button you will hear the sound.
6. Now again tap the Plus icon (+) > 'Widget' > and here you can choose the default Total Launcher audio widget, or if your preferred audio player app has its own widgets, tap 'Application Widget' then tap on the widget you want. If you use the default media controls widget, tap on the '?' icon to select the media app you want to control.
7. Follow the above stages (4,5, and 6) to add all of your buttons and widgets. And we are pretty much done with the dashboard.

On-screen Volume Controls:

To achieve this you will need the 'Tasker' app installed and set up with all of the system permissions accepted.

1. Open up Tasker, press the plus icon, then 'Create', now name the task 'Volume up' and tap the tick button.
2. Tap the plus icon, then in the filter section, type 'Media' and tap 'Media volume'. In level, write '%VOLM+2', press the back button, tap the 9 square dots icon at the bottom of the screen, select an appropriate icon, then press the back button again. The number '2' is the increments the volume will go up, and can be changed. I found 1 to be a little slow requiring more button presses, but 2 suited me.
3. Follow the same processes for volume down, but using '%VOLM-2'.
4. keep pressing the back button to exit tasker.
5. Follow the Total Launcher process to add a 'Text' element, now click on the Play icon. Here you click on 'Action' and then scroll down to 'Task Shortcut' and choose the the volume up task, then repeat the process for the volume down button.

And that's the basics for the UI. Now to fit the equipment.

1. Apply double sided tape to the front of the tablet holder.
2. Remove the backing tape and attach the tablet to the holder, making sure you don't block off any ports.
3. This is where things will differ on different vehicles, but hopefully the way I did mine will give you ideas to fit yours. On my car, there is a small cubby hole just below the heater controls. This is a removable part separate from the dashboard so there is a join gap that I use (two in fact, top and bottom of the cubby hole). I simply managed to work the folding foot of the tablet stand into the gap and push the tablet in. A screwdriver of trim removal tool may help with this. Once the tablet has been removed a few times, the plastic trim will form a memory of the position making it easier to insert and remove the tablet stand.

Look for places were you can insert the end of a tablet stand into in your vehicle. Ideally not obstructing any vehicle controls, an area where it is easy to access, and hopefully somewhere where it looks good and looks like part of the car. In my car, with the tablet flush against the dash, it does cover the factory fitted stereo buttons a bit, but if it is pulled out slightly, I can tilt the tablet back a little thanks to the adjustable stand and use the buttons if I need to (which I actually hardly ever do).

Other mounting options are making your own holder using some plastic sheet, using a tablet case with an appropriate built-in stand, or even mount the tablet over your rear view mirror. With the screen off, the reflectiveness of the screen should be good enough to use as a mirror (similar to rear view touchscreen dash cam mirrors) or even add a camera to the back of the vehicle and view the images on the tablet.

My car is a hatchback so it has a removable parcel shelf. But a soundbar can also be fitted to a fixed shelf. This is how I did mine...

1. I removed the parcel shelf from the car, placed it on a work table and placed the soundbar on top.
2. I made four holes, two each end, front and back of the soundbar.
3. Then I fed through two large heavy duty zipties through the holes from the under side of the shelf, wrapped them around the soundbar, into the other hole and zipped up the tie from underneath the shelf making sure they were tight and that the soundbar was completely secure. NOTE: I actually fitted the soundbar to the underneath the parcel shelf so it is out of sight, and it still sounds great.

To fit the inverter, I needed to extend the cable that comes from the inverter to the 12c plug.

1. First I cut the cable, stripped the ends, and did the same on an extra length of spare cable. I tinned the wire ends, slid over some heat shrink tubing, soldered the wires together and covered the joins with the heat shrink tubing using a lighter.
2. I placed the inverter in the back of the car, then traced the cable from the back to the front hiding the cable under the plastic door trims running along the cars floor. The last end of the cable I traced under the dashboard, ziptieing it so it was safely out of the way, and plugged the 12v plug into the cars 12v cigarette lighter socket.
3. Then it was a simple case of plugging in the soundbar to the inverter and powering it on.

One thing to note, most vehicles that have a 12v cigarette socket power up when you turn the key or press the start button, but there are some vehicle where this socket is wired up so it's permanently live. If your vehicle is wired this way, then you will either have to remember to unplug the inverter or put in a power switch.

1. Finish off by fitting the parcel shelf (if it's removable), plug the power cord into the soundbar and the inverter, and plug the inverter into the cars 12v power socket if you haven't done so already.
2. Power on the soundbar and set the mode to Bluetooth, then turn on the tablet, go to 'Settings' > 'Connected Devices' > 'Pair New Device' look for the soundbar and hit 'Connect'.
3. As a final job, open 'Settings' on your phone, 'Network & Internet' > 'Hotspot & Tethering' > toggle 'Wi-Fi Hotspot' to 'On'. Then open 'Settings' on the tablet, then 'Internet', tap on 'Wi-Fi Preferences', then tap on your phones name to connect.

All that is left to do is to crank some tunes, and enjoy. Have a play about with any EQ settings you tablet and soundbar may have to get the best out of you audio library whether it's music or audiobooks. This setup is working well for me although now I have tried the proof of concept, I may invest in a better soundbar with a subwoofer.

I hope you enjoyed this little Instructable, and if you give it a go, I'd love to hear about it.

Thanks for reading, and happy making.