This is a simple project to teach soldering and electronics to kids (10+ years) and beginners. I first thought of a simple two transistor LED flasher, but then decided to make it interactive by adding a touch sensitive element to it. The idea is that once made, this PCB can be worn as a badge.
Step 1: Schematic
The touch plate consists of a few closely spaced copper tracks, and when you put a finger across a track, it acts as a resistor, sending a small current into the darlington pair Q1 + Q2, which amplifies the current and switches on the bistable multivibrator circuit formed by Q3 + Q4. The circuit is powered by a CR2032 coin cell.
Step 2: PCB
I’ve uploaded my gerbers to OSH Park. You can order PCBs from them using the link below.
Step 3: Components
You can find all design files for this project, including the Bill Of Materials (BOM) and gerbers, at my github link below:
Step 4: Soldering
Soldering blinky badge is easy. Don't be intimidated by the surface mount (SMD) components. Actually once you get the hang of it, soldering these is quicker than through-hole components. Here is a fun cartoon guide to soldering with SMD components:
Step 5: In Action
Here's the badge in action...
Step 6: More Details
You can read more about this project at my website below:
Have fun soldering Blinky Badge!