MINI DESKTOP COMPUTER
RASPBERRY PI
Project Overview
I needed a portable display for my Pi and Amazon had really great options but the ones I really liked were a bit too pricy. I came across a $72.79 7 inch Touch screen monitor that was equipped with PIS display with a resolution of 1020X600 and with dual speakers. it was also giving a bunch of ports for connectivity. It was just a bit too pricy and I have kids to feed so I thought of making one myself with what I already had around the house. To learn more about how I built this screen, keep on reading.
DISPLAY
I scavenged this display from a broken laptop one of my friends gave me. The laptop was good externally but had coffee stains all over the motherboard. I cleaned it with toothbrush and sanitizer to see if there was a way it would start to work again. Unfortunately, it refused due to some components being shorted and burnt. So, I decided to disassemble working parts such as this screen.
DISPLAY DRIVER BOARD
Now to make it useable, I needed a driver board for the display. Using some product information that was provided in the back of the display, I found a cheap driver board that was for a bigger laptop with 15.6" a 40Pin LCD Panel. It was way too outdated but I needed all the ports that it came with so that this monitor would be equipped with all kinds of ports and can be like a desktop computer. It supported my display and so I went with it. This driver board is equipped IR interface, KeyBoard, 30P LVDS Interface, Inverter, Speaker, Power Supply, HDMI, DVI, VGA, Audio and, Earphone Out. Again way too old if we compare this driver board with the modern laptops and I really don't need most of the ports either but for the price, I had to get.
Pi
The main player of this project is Raspberry Pi 3 b+. There isn't much to say about this guy but I had few laying around the house from previous school projects ended up using one for this project. The problem is that both the Pi and the driver board need a power input of their own so there would be two wires that would need to be plugged in for the computer to work. Pi needs a 5V-2.5A input and driver board needs 12V-750mA to operate. In order to make use of only one power supply, I did a bit of calculation using the voltage divider formula. I chose my primary input to be the 12V supply and from there I can choose R1 and R2 so that my output voltage or voltage across R2 = 5V. Unfortunately, Pi has an internal resistance that is in parallel with R2 and this created a big problem. I can no longer use the voltage divider unless I choose my R2 to be the resistance of Pi and choose R1 accordingly. Doing this resulted in a very low current which was below the required minimum of 2.5A.
SOLUTION
The solution was Pololu 5V, 2.5A Step-Down Voltage Regulator. This little guy is DC-to-DC converter that takes a range of input voltage from 4.5V up to 38V and efficiently reduces it to 5V and allows a typical continuous output current of up to 2.5A with measured efficiencies of 85% to 95%.
