Touch Activated Blinky Badge

Introduction: Touch Activated Blinky Badge

About: Open Source Hardware Projects - Microcontrollers, Programming, and new prototyping technologies.

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!

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    Butane Flame
    Butane Flame

    7 years ago

    Thanks for the walk through. I don't intend to use the badge aspect of this tutorial, but I'll tinker around with with interactive aspect of it.


    Reply 7 years ago