7

FORGE

I

t’s no secret that at HackSpace, we are

hooked on the Circuit Playground Express.

With so many on-board sensors and lights,

we keep thinking of new ways to use it!

This project is inspired by Angela Sheehan’s

fairy wings project – she uses a colour sensor

in a magic wand to ‘collect’ colour from an object, while

the lights in her wings change to match that colour

• brilliant! In our build, we’ll mimic this by using the
  built-in light sensor on the Circuit Playground Express,
  and a strip of NeoPixels inside a clear handbag. Change
  the colour of the lights in your bag to match your outfit,
  or a found object while you’re out and about!
  The circuit for this project is simple, and can be
  used in any project where you want to connect an
  external strip of NeoPixels to your Circuit Playground
  Express. Instead of sewing the circuit, we’ll do some
  light soldering to connect everything together. Coding
  is easy with MakeCode, and once your project is
  complete, you can quickly modify and develop your
  code further, as the CPX remains easy to access on
  the front of your bag. The NeoPixel strip will be on the
  inside of your bag, so we’ll need to pass wires through
  holes punched into the front. Choose a bag that you
  are willing to dedicate to this project for good. (Your
  author purchased the bag shown for about £25.)
  The transparent ‘holographic’ coating on this bag
  makes a great surface for reflecting the NeoPixel

Left

Gradual, even

pressure is the key to

making clean holes

in plastic

LEDs, and it really shines in low-light conditions.

Adafruit’s NeoPixel strips are available in several

different options, with varying densities of LEDs along

the strip. The 60 LED per metre option (shown) is

easy to work with, with bigger pads and easy-to-read

markings. Advanced makers can intensify this project

by sizing up to 144 LEDs per metre! NeoPixel strips

are sold by the metre, but for most handbags you’ll

only use about 25 cm. Let’s get started!

LET’S MAKE SOME HOLES

First, we’ll mark the placement of the holes we

need to make to pass wires through the front of

the bag. Place the Circuit Playground Express on

the front of your bag, with the USB port at the top

and the JST port at the bottom. Use a Sharpie to

mark holes that the wires will go through: GND

and VOUT on either side of the JST port, and A1.

We’ll also need some holes for mounting the CPX,

so mark these four holes we won’t be using in our

circuit: GND and 3.3 V at the top, and A0 and TX/A7

at the bottom.

Set the Circuit Playground Express aside, and use

an awl to make the holes you’ve marked. Align the

awl precisely: there’s no going back once you’ve

made a hole in plastic. Twist the awl and slowly

press to make holes about 1 mm in diameter. Take

your time so as not to crack the plastic.

YOU’LL NEED

Materials

Clear handbag

with a flat bottom

Circuit

Playground

Express

NeoPixel strip

Silicone-coated

stranded wire

30 AWG

3 × AAA battery

pack with on/

off switch and

JST connector

Clear packing

tape or Gorilla tape

Small cable ties,

101.6 mm length

Tools

Awl

Craft knife

Basic soldering

supplies

Masking tape or

colourful washi tape

Scissors

Third helping

hand