2019-06-01_New_Scientist

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

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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]