Dual Screen Media Player for Cars & Kids With Old/reused Kit

There is an specific product and service for anything we can think of, but so many times we end up paying twice (or more) for the same things: screen-stuff, data plans, etc.

I have two kids now (2 and 4 years old) and a 5 hour journey from where we live to where I grew up, and the kids spend part of the journey watching cartoons.

This project is my solution to have dual screens, optional internet access, minimum cost and reusing stuff, all with a pretty neat setup.

So here is my really simple, really cheap project.

• "Master" tablet, anyone really, Lenovo M10 FHD in my case, the app used in this project is only available for Android but similar apps may be available for iOS
• "Slave" tablet, anyone with a browser and WiFi will fit, regardless how old it is, I am using a 32bit obsolete iPad mini
• "hotspot wifi" dongle. In my case I have used an old WiFi Extender with some modifications.
• DC-DC converter (due to the modification above)
• Screen Stream over HTTP (play store)
• Your smartphone - optional - to provide internet access to the hotspot.

I strip off an old WiFi range extender and I split it in two parts. The power source and the actual wifi extender. I couldn't find the output voltage of the power source so I had to measure it with the multimeter, so I need 3.3V

To feed it from my car I used a USB socket in my arm rest but had to add a DC voltage regulator to lower the output to the 3.3V required.

I soldered the V+ and Gnd to the USB cable and fitted directly into the WiFi Extender module.

This step can be really simplified getting a USB WiFi Extender dongle.

Install Screen Stream over HTTP either on your Android or iOS device:

https://play.google.com/store/apps/details?id=info.dvkr.screenstream&hl=en&gl=US

Connect the tablet to the WiFi Hotspot

Open the app, start casting and note the url

Connect the second tablet to the WiFi Hotspot.

Go to any browser (I am using Chrome) and enter the address obtained in the previous step, you may want to add it to the bookmarks for quicker access, and you will start receiving a mirror view of the master table in the browser.

Make sure you set up the device correctly so the screen doesn't turn off automatically after certain period of inactivity.

And we're done!

You can adjust the quality of the stream to minimize the delay between the two tablets, the quality will obviously be significantly lower.

Since I don't always have previously downloaded the content my kids want to watch, I added my smartphone to the setup so if I simply turn on my smartphone's hotspot, the whole network will gain access to the internet using my unlimited data plan.

I personally decided to pair the Bluetooth of the Master device to my car so I can take control of the volume. It is obviously better quality than the tablet speakers, and more importantly I can adjust the output to the rear seats only :-)

This setup is neat but tablets may run out of battery at some point obviously. I will be charging the tablets in advance but obviously adding a charging port is straight forward, but I wanted to add this somewhere so anyone implementing something similar don't think I completely missed this point.