BLINKY BOARD
555 TIMER AND SMD COMPONENTS
Project Overview
When I am in my office, my son likes to hang out with me and watch me work on projects. He comes to me one day and asked me to make him blinking lights toy. So I used a mini Breadboard to make him a prototype using some passive components and 555 timers on which he helped me. He loved it but the problem was a huge 9V battery and hanging wires so I designed him 2X1 2 layer PCB on EAGLE with SMD components and a 3V nickel battery that is not only small but looks cool and has his name on it. I used SEEED Fusion PCB fab services for PCB fabrication and mounted the 0805 components myself at home and cooked it in T-962 Reflow Oven.
EAGLE Schematic
I used EAGLE to design the circuit and board layout using the available diagrams and footprints. Most of the components had both the footprint and the diagram such as capacitors, resistors, and LEDs in EAGLE as I had previously downloaded the Adafruit Library for components. Some components were not available in the EAGLE library but they were readily available on Snap EDA. Unfortunately, one specific component was not available anywhere. The EVQ-PNF05M is the SMD switch that I used so that the circuit I designed does not stay active forever and can be controlled VIA the switch. I could not find it so I had to design its diagram and footprint in EAGLE.
FOOTPRINT AND DIAGRAM
I really like using EAGLE for a number of reasons but the main one is the simplicity of having the part diagram and its footprint organized and stored in libraries. This provides an easy way to keep parts organized based on their category. Some parts may not be available and can be found on Snap EDA or Digi Key and some parts like the EVQ SMD switch may not be available at all and you and that was the case for this project. I had to design the package library for the switch and it was fairly easy to do. EAGLE is very user-friendly and this part library was my first ever. I did not realize the size of the diagram when I was designing it on EAGLE but it turned out to be huge.
BOARD LAYOUT
The toughest job for any PCB project is the layout. EAGLE comes with an autoroute feature that makes things a bit easier but you may not be satisfied with how it looks and maybe in some cases, you might have some overlapping of wires and that you can't do so you may have to route some wires yourself. In my case, I used the auto-routing feature but I did not like how it did the routing. I looked a bit messy and unprofessional so I routed the entire board manually. One problem I faced was an Iceland created near the 555 Timer. The blue wire on the board in the picture was overlapping other wires. To solve this problem, I added an extra layer to connect this wire from the bottom layer.
Board Layout
PCB FABRICATION
I wanted this PCB board to be more of a gadget keychain than a boring rectangle. EAGLE originally lets you work in a small rectangular window for layout and it can be customized to your desire which is another thing I truly love about EAGLE. So, instead of having a 2 X 1 rectangular PCB board, I used the miter tool to redesign the PCB to look more modern and cool. I added a hole in the bottom left corner of the PCB so that I can tie wrist lanyard strings so the kids can have it tied on to their wrists while they play and learn.
REFLOW OVEN
REFLOW OVEN
There are many options when it comes to SMD soldering. I have personally used this specific reflow oven in one of my previous projects and to be honest with you, I loved it. There are a lot of complaints regarding the issues that this thing is packed with as far as the temperature is off by 90 degrees, selection bottons get stuck once in a while and finnlay, the smell of the masking tape that they have used to keep the insulation inplace is unbareable. When I used it for the RF-EH project, I did have to cook the board twice and the smell was present. The only modification I did was replacing the masking tape with Kapton tape as it does a much better job in high temperatures.
REFLOW OVEN MODIFICATION
SHORT VIDEO ON MOD
a SHORT vIDEO ON hOW i REPLACED THE MASKING TAPE.