Make: Volume 52

5. ASSEMBLY

Before you assemble the Monster-B-Gone

in the project box, I highly recommend

wiring everything up outside the box and

testing first. Pay careful attention to the

wiring; one misplaced wire could result

in a damaged Trinket or NeoPixel LED, so

double-check all your connections against

the wiring diagram (Figure

J

).

Once everything is wired up, flip the

battery box switch to the On position (after

inserting the batteries, of course) and

press and hold the pushbutton (it takes a

few seconds for the Trinket to boot up). You

should see a short animation of spinning

blue lights, followed by the all-green “coast

is clear” lights.

If you’re not seeing any animation, you’ll

want to check all your wiring again. If the

Trinket is powering up (a solid green-yellow

LED stays lit when it’s powered) but the

NeoPixel animation isn’t playing, you’ve

likely got a wire connected to the Trinket

incorrectly. Verify the Data Input header

on the NeoPixel Ring is connected to pin

0 on the Trinket. If you’re still not seeing

any animation, verify you’ve uploaded the

MonsterBGone sketch to the Trinket.

Once you’ve got the animation playing

on the NeoPixel Ring, it’s time to pull

everything apart and reassemble inside the

project box (Figure

K

). Wire everything up

as before and use velcro or double-sided

tape to secure the battery box inside the

project box. You might also want to use a

dab of hot glue (in place of tape) to secure

the Trinket to one of the inner walls as well.

Use the project box’s screws to secure the

lid in place.

headers) on the project box lid and make 3

small marks where the headers touch the

lid. Drill a ¼" hole at each mark, then test-

fit the NeoPixel Ring (and shell, if you’re

using it) and ensure the headers fit into the

drilled holes (Figures

G

and

H

).

If the headers can be reached from

beneath the lid, glue the shell to the project

box lid and set the NeoPixel Ring aside

until final assembly. (If the headers can’t be

reached, you may need to drill the holes a

little larger.)

Next, decide where to place your

pushbutton. I drilled a ½" hole in the left

side of the project box (Figure

I

), but it

could easily be mounted on the box lid

beneath the location of the NeoPixel Ring.

4. PROGRAM THE TRINKET

To program your Trinket, first you must

install the latest Arduino development

environment (IDE), version 1.6.9 at the time

of this writing, and update it to recognize the

Trinket. Adafruit has detailed instructions

for this task at learn.adafruit.com/

introducing-trinket/introduction. Be sure to

follow those steps related to your specific

operating system (Mac or Windows);

Windows users will also need to download

special Trinket drivers.

Once you’ve got your Trinket blinking

using the Flash test program, you’re in good

shape. All you need to do now is replace the

Flash sketch (program) with the modified

Monster-B-Gone sketch. Download the file

MonsterBGone.ino from the project page at

makezine.com/go/monster-detector, open

it in the Arduino IDE, then hit the Upload

button to load it onto the Trinket.

6. FINISHING TOUCHES

I created my own graphics for the top and

sides and had a local print shop print them

for me on a vinyl sticker sheet. Then Make:

illustrator Brandon Steen came up with

the awesome purple monster design you

see here. You can download the monster

graphic from the project page at makezine.

com/go/monster-detector.

UPGRADES

Where to go from here? An obvious choice

would be to add a sound effect. One easy

way would be to use an inexpensive sound

recording module (such as RadioShack

#2761323). Drill some tiny holes in the

project box, hot-glue the speaker in place,

and wire the module’s Play button directly

to the Monster-B-Gone pushbutton so it

triggers your sound effect.

And I’ve always liked the moving arms on

the “P.K.E. Meter” in the movie Ghostbusters

— a couple small servos could be easily

added, one per side, with holes drilled into

the project box for the shafts. Create an

eye-catching “antenna” for each motor and

you’ve got sound, lights, and motion.

I hope you like the Monster-B-Gone.

Even better, I hope some children will find

peace at night when their parents introduce

them to this useful device. Imagination is

a powerful thing, and giving a child a tool

(and letting them help you make it!) to help

combat an imaginary monster can turn a

parent into an instant hero. Have fun!

Brandon Steen

makershed.com64

PROJECTS

Download the project code, optional 3D file,

and graphics, and share your build at

makezine.com/go/monster-detector.

Monster Detector

G H I

M52_062-5_Monster_F1.indd 64 6/14/16 12:31 PM