Introduction: PCB Snowflake Ornament

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This project was an entry in #NextPCBchristmasCompetition held on Instagram in December 2020 and won the Third prize.

The theme was to design a PCB based around Christmas so what suits better than snow? This PCB utilizes 12 LEDs driven in pairs by a simple transistor - R-C pair flasher (astable Multivibrator), placed in a symmetric snowflake surrounded by shiny stars!

Supplies

Components required :

  1. SMD NPN transistors (BC817 in my case) - 12
  2. 100KOhm 0603 resistors - 24
  3. 330Ohm 0603 resistors - 12
  4. 10uF 1206 Caps - 24
  5. CR2032 battery holder -1
  6. Snowflake Ornament PCB

Step 1: Designing the PCB in Altium Designer

I design all my PCBs using Altium Designer.

The idea was to design a small PCB which can be powered with cheap low capacity CR2303 batteries and hence usage of transistors and passives like RC eliminated the need of a microcontroller.

The values of R and C determine the frequency of flashing operation given by the simple formula below:

f = 1/(0.68*2*R*C)

In my case, R = 100K and C = 10uF , hence f = 0.73Hz and Delay comes out to be 1.37s

More detailed info on the circuit theory can be found on this link:

https://www.petervis.com/GCSE_Design_and_Technolog...

Design schematic and PCB snapshots can be seen here.

Specs:

  • Round PCB
  • 45 mm Dia
  • 2 layer 1.6 mm
  • Matte Black soldermask
  • FR4 , HaSL

Step 2: Ordering PCBs From NextPCB

These PCBs were ordered from NextPCB from the prize money deposited in my account.

Steps to order:

  1. Click on PCB instant Quote
  2. Upload your Gerber file (zipped file)
  3. Set the parameters (Number of PCBs, Color, etc.)
  4. Select shipping method and add to cart

Once the Gerber files are verified by NextPCB, you can proceed with payment and finish the ordering process.

These PCBs were manufactured and delivered to me in 7-8 days!

Step 3: Soldering the Components and Testing the PCBs

As the resistors used are 0603 package, manual soldering took about an hour to be finished completely.

Battery socket was soldered in the end and the PCBs were tested.

Gerber files will be made available if requested.