2019-06-01_New_Scientist

(singke) #1
1 June 2019 | New Scientist | 51

New stuff you need
DC motor
Plastic bottle
Straws
Wooden skewers
More cardboard


For next week
3V battery
BBC micro:bit starter kit


Next in
the series
1 Introduction
2 Electric candle
3 Toast notifier
4 Desktop traffic light
5 Propeller car
6 Magic eight ball
Basic coding gives
your device a brain
7 Theremin
8 Sound-sensitive
disco ball
9 Rubbish sweeper
10 Biscuit bot


AT THE halfway point of your
maker journey, it’s time to really
get moving. The simplest way
is with a motor, which converts
electric power into spinning
motion. That’s got some obvious
appeal for applications such as
wheels or fan blades, but motors
pop up everywhere, from vacuum
cleaners to computer hard drives.
Look for a motor with a voltage
range that encompasses the
voltage of your battery. Mine
says 3V to 12V, for example. If your
battery supplies higher voltage
than the maximum, you risk
damaging the motor. If it delivers
less than the minimum, it may
run poorly or not at all.
Motors work because electricity
and magnetism are two sides of
the same coin: where you have
one, you usually get the other.
When an electric current passes
through a coil of wire in the centre
of the motor it produces a
magnetic field. This creates an
attractive force between the coil
and permanent magnets in the
motor’s casing, causing motion.
See for yourself. Connect the
motor’s two wires to the battery
terminals, and the rod protruding
from its middle will spin. Recall
how LEDs only work when wired
one way round? Motors aren’t so
fussy. Reverse the wiring and the
rod will spin the opposite way. You
can control the speed by altering
the power – add some resistors to
your circuit to see this effect.
For a more satisfying demo,
slice the top off a plastic bottle and
make a small hole in the centre
of its cap. Then, cut some petal

shapes from the rest of the bottle
and glue them so they extend
from the curved part of the cut-off
bit. What you have made should
look like a propeller. Slip the cap
onto the motor rod (while it’s not
spinning, of course) and glue it in
place. Now you have a mini fan.
Or make a propeller-powered
buggy. Glue two drinking straws –
not plastic, now! – along opposite
edges of a rectangle of card. Slip a
wooden barbecue skewer through
each, leaving a bit sticking out
of the ends. Cut four circles from
some more card, then poke the
skewers through their centres and
glue them together. Attach your
battery and propeller to the

card platform and watch it go.
And there’s so much more you
can make. How about a motorised
duster? Just glue some cloth to the
propeller blades. Or add legs rather
than wheels to make an automatic
pot stirrer. You could use it to
amuse your pets by attaching
string to the motor and have it
wind in when you press a button.
Finally, what about a bath foamer:
position the motor so that long
spokes off its shaft disturb the
flow from a tap and create more
bubbles (beware: electricity and
water don't mix!). ❚

Thanks to Imperial College Advanced
Hackspace for use of their facilities

How to be a maker Week 5


Time to get moving


Adding a motor makes things much more interesting, as
Hannah Joshua demonstrates with a propeller-powered car

Puzzles
Quick crossword,
a disappearing sock
mystery and quiz p52

Feedback
Zombie climate
change apocalypse:
the week in weird p53

Almost the last word
Burning rubber
and heating toast:
readers respond p54

Me and my telescope
Tana Joseph on
binary stars and her
cartoon motto p56

What does...
Liana Finck?
A cartoonist’s take
on the world p53

The back pages


DA

VID

ST

OC

K^ F

OR

NE

W^
SC

IEN

TIS

T

Hannah Joshua is a science
writer and maker based in
London. You can follow her
on Twitter @ hannahmakes


Make online
Projects so far and a full list of required kit are at
newscientist.com/maker Email: [email protected]
Free download pdf