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Electronics

Arduino
Main Boards
A low cost embedded controller with open hardware licensing. It is supported by a range of 'shields', which are stackable daughter-boards offering a wide range of functions (e.g. LCD, CANbus, WiFi, Ethernet, Sound, SD card, etc..).
Arduino UNO: Base level board. Usually has DIL IC socket meaning chip can be upgraded/replaced. (Typ. £9 UK, £6 China)
Arduino Mega 2560: Bigger brother with more I/O and memory. (Typ. £11 UK, £9 China)
Freeduino: Arduino Diecimilia equivalent.
 
Shields
Here are some shields that I have used;
Wave Shield: [Adafruit v1.1 schematic]. Audio playback of WAV files from an on-board SD card. (Typ. £18 UK)
CAN-BUS Shield: [v12 DEV-10039 sparkfun schematc] CAN interface with uSD card holder for logging. (Typ. £36 UK)
RS232 Shield: [CuteDigi.com / linksprite ... v1 schematic]. Adds a RS232 interface. (Typ. £15 UK)
Screwshield: Twin style breakout terminators [WingShield] or single board [ITead Studio] with small prototyping area. (Typ. £4 UK)
 
Add-ons
GY-521 Module: Small breakout board [schematic] using the MPU-6050 chip [InvenSense], a 3 axes Gyroscope + 3 axes Accelerometer Module. (Typ. £7 UK)


Raspberry Pi
A low cost Single Board Computer running a variant of Linux. Has peripherals for things like USB inputs, HDMI video output, SD card, Ethernet port, etc..
Raspberry Pi 1 Model A: Now defunct.
Raspberry Pi 2 Model B: Second iteration. (Typ. £30 UK)
Raspberry Pi 3 Model B: Third iteration. Adds WiFi and BlueTooth. (Typ. £36 UK)

Connect to NAS drive
Instructions here and here.
Add folders ... /home/pi/DiskStation/openshare
Edit drive mapping file ... sudo nano /etc/fstab
Add the mapping to the end of the file ... 
//192.168.1.99/openshare /home/pi/DiskStation/openshare cifs username=?????,password=????????????,_netdev,x-systemd.automount  0  0
Save (<Ctrl>+X) ... confirm modify (Y) ... confirm filename (<Enter>)
Won't activate until next boot but cn be tested using ... sudo mount -a


DIY PCBs
The following process explains how to make your own PCBs ... and it works surprisingly well;

Step 1: Design PCB
Eagle provides a popular free version.
Consider filling large blank areas with mask regions as this will minimise the amount of copper to remove, lessen the time and improve quality.
Filter the layers to just Bottom Layer, Pads & Vias.
Export to a monocrome image, using a minimum of 600dpi resolution.
Note: Consider using a PCB manufacturer (like Elecrow) for a quality solution.
Step 2: Laser Print Mask
Print the mask layout using a laser printer (deposits 'plastic' ink) on to Photo Glossy Paper (as ink can be removed with heat).
Stack several images on to one sheet to minimise costs, as more than one attempt may be needed to adhere the mask.
Note: Be careful with mask orientation, print a Bottom Layer mask normally, a Top Layer mask would need to be inverted.
Step 3: Adhere Mask to Copper
Clean the copper with Acetone (nail polish remover).
Cut the mask only a little bigger that the board (to allow room for tape).
Lay the copper side of the board down on to the mask image (ink) and align.
Tape the board down on to the photo-paper so that it will not move around.
Step 4: Heat the Board & Mask
A laminator works great! Run the board through about 20 times, flipping it over each time and moving it along the length of the machine.
Take your time, the more heat and pressure the better for adhering the ink to the copper.
Other people use a clothes iron but the laminator is great for applying pressure as it heats ... and its simple to use.
Step 5: Soak the Paper Off
Put the board in to a shallow tray and cover with lukewarm water.
Leave the paper to soak for a good while, it will eventually lift away from the board on its own.
Don't scrub at the paper as you are likely to scrub off the ink too. Be patient, just keep soaking and rinsing.
I find that a bit of the photo-paper 'glue' can remain attached to areas of the ink, just leave them, they won't hurt.
Step 6: Etch the Board
Wear Gloves, and Eye Protection !!!
Dilute 50g of Sodium Persulphate (Maplin kit) to 250ml of warm water (50degC to 60degC).
The solution can be stored in a plastic drinks bottle, so it's good to mix it in this and then pour in to the etching tray.
Drop in the board in to the solution and rock the tray backwards and forwards, constantly washing the solution over the board.
Remove the board when the etching process has removed the desired amount of copper.
The solution with turn blue as copper is dissolved.
Step 7: Clean Up
Run the etched board under water to clean, then use acetone to remove the mask ink.
Do not pour the solution down the drain, it not allowed in the sewage system.
Pour the solution back in to the drinks bottle and leave the lid loosely attached, allowing emitted oxygen to vent off. 
Any spillage should be washed down to dilute it, and waste fluid should be diluting before being disposed of.
Some use neutralising agent that turns the chemicals back to a powder, for disposal.
Step 8: Trim and Drill
Trim the board to the desired size and shape.
Use a 1mm drill for the through holes.
Use a Dremel with a suitably sized collet.

Then  solder and enjoy !!!


 Links
Here are some Electronics links which may be of interest (with a star rating out of 5);
Tools:
***** Arduino Official website, Arduino IDE, Reference guides, tutorials, forums.
 **** Eagle Schematic & PCB design tools. Free version, limited, non-commercial.
Stores:
  *** Proto-PIC UK online store.
  *** Cool Components UK online store.
   ** Elecrow Chinese PCB manufacturer. Low volume (min 5 off) and cheap (10 off 10cm x 10cm .. paid £7.80 in postage).
 
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