HOT Raspberry Pi DIY Mini Desktop PC Build

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Constructing The HOT Raspberry Pi

Next, we wired in our main power switch for the Raspberry Pi itself using a rocker on/off switch. We cut a hole in the opposite side of our case and inserted the switch. It is glued down from the inside for a neat and sturdy fit. The cable used is a micro-USB cable that runs to our 5 volt battery that is placed inside of the enclosure. The wire was spliced half way down the cord and connected to a single-pole, single-throw switch. After solder was applied to each lead, hot glue is used as an sealant to make the bond more durable. The battery pack is located on the opposite side and opposite corner of the Raspberry Pi, on the top of the enclosure.


The Micro-USB runs through the switch and directly to the board which is mounted with standoffs.

Next, to mount the board itself down we used stand-offs that fit in the pre-drilled holes in the PCB. Hot glue again was used for a strong adhesion with the standoffs to the base of the enclosure, but the screws that mount into the standoffs still gave us access to remove the board when we please.


Shown is the finished power supply with the bare mono-jack

Now that we had the computer in place, we started to focus more on the display aspect of the project. We ended up deciding on a 7-inch LCD display that is often sold as a reverse backup camera display for vehicles.  It's a full color display with 480x234 resolution - one word, "inexpensive." We then had to decide on which AC adapter was best suited for our display.  From there, we stripped the end connector off (our display didn't come with a power supply), and then took a 3.5mm mono-jack and mono-port and soldered the jack to the stripped end of the power supply. We then drilled a hole in the back of our enclosure that was the diameter of the port and mounted that down. After that, we soldered our cathode and anode off of the port and did the same with the power supply.





The next step was to connect our display by splitting the power cables and rewiring the male RCA cable. A female composite video connection was soldered directly off of the PCB to conserve room to help make running the display's input RCA connector easier to connect.



Once we were done testing, we drilled a hole in the top of the case so that the power cord could run to the mono-jack that we previously installed and so that our RCA cables could pass through to the board. We trimmed down the cable, getting rid of at least 3 feet. This cable was too long because the wire itself was made to run through a car to reach a car battery as a power source. A piece of perforated circuit board holds all 16 of the small individual wires that were inside of the main cable we cut down. The board is shown wrapped in electrical tape here.  It wasn't a simple splice, so we had to improvise a bit.

The last steps included cleaning up all of the loose cables with zip ties and Velcro, trying to make everything fit. We pushed the cable for the display through the hole into the top and mounted the display down with the provided adhesive pads. Then, we screwed everything together, and our project was complete.



Challenges:

Over the course of the project there were many issues we ran into. The major problem was setting up the internal power supply. Every time the supply needed to turn on, it required a button to be pushed. This meant we had to open the computer every time we wanted to use it. To solve this issue we rewired and jumped a small push button to the back of the case.


Also, we ran into the issue of running out of storage capacity while compiling software and games onto the SD card, ruining our first OS and rendering a 4GB SD card useless. We solved this by upgrading to a 16GB SD card and re-installing the Linux image to it. Lastly, as noted, the absurdly long cord of the display, which took up too much room to contain in our small chassis, was solved by manufacturing a perforated board connector on each end.  All told, these were relatively minor hiccups in the grand scheme of things.

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