I wanted something other than AM, FM and CD in the old Ford.   So I purchased a cheap Chinese 7″ Android tablet and a small two channel 20w amp on eBay.  I also purchased a wiring harness to match the truck, so I can undo this mess in a hurry; if I have too.  I could not find a cheap 4 channel, so front and back speakers are tied together.  Yes, I checked the ohms to make sure that would not kill the amp.  I removed the original radio, plugged in the wiring harness and began to solder.  The amp is connected via the harness to the speakers, the amp is connected to the tablet via the “headphone” jack.  The tablet is mounted with some homemade brackets and yes a little Gorilla duct tape.  I had to mount the tablet outside the dash because of the location of the ‘on’ and ‘volume’ buttons.  The amp is powered via the power that powered the old radio, the tablet is powered from an USB cord that hangs out of the dash and can be plugged into an adapter for charging.  Yes, that makes no sense, why not just wire the tablet to the ignition, like the amp.  Some reason I am getting a crazy amount of AC hum from the alternator, I mean a LOT; very LOUD.  I have tried the circuit pictured, I created two DC noise filters, the one on the amp worked great and filtered 99% of the noise.  But, the one on the USB charging cable does very little.  If the engine is running and the tablet is plugged in, you have about 30 seconds before going absolutely mad from the noise.  I may try a different circuit in the future, but for now I just charge the tablet and run off the battery, it works.  It’s a little redneck, but I like it. I can tether wirelessly to my phone and listen to Pandora on the road, or use Google Maps for navigation.  If I could change anything I would have purchased a better tablet, this one was $60, and you can really see the lack of quality.  What really blew my mind is the screen is plastic, yes plastic.   I thought it would be cheap glass, but plastic, really??  I think I spent a total of $100, fun little project.

Products used:

• 7″ Super-Cheap Tablet
• 20W Amp
• Ford Wiring harness
• Miscellaneous electronic parts for the DC noise filters