Asi
Easy-wear arachnid
with LED matrix eye
to scare neighbors.
Inspired by African
spider god Anansi, the
trickster/storyteller.
Odin
Small wearable bird is
a quick build for kids.
Inspired by Alex Glow’s
familiar (“Archimedes:
AI Robot Owl”, Make:
Volume 66).
Sun
Astronaut-themed
wearable bot, inspired
by Sophy Wong’s
amazing spacesuit
(“Cosmic Cosplay,”
Make: Volume 69).
Prometheus
Alien-like design with
analog, animatonic
moving eyeballs
instead of LED matrix
animation.
Widget
Skyrim-inspired
dragon with optional
vape-pen smoke
module. Built with
Adafruit Crickit and
Make: Code.
My Companion
Bot Menagerie
I’m a workaholic. I love building robots. It’s been
a busy year! You can find all my companion bots
at hackster.io/Odd_Jayy.
H
I
Jorvon Moss
83
makeprojects.com
PROJECTS:
Bike Wheel Wind Turbine
Backyard
Wind Power
Written and photographed by Ulrich Schmerold, Translation by Niq Oltman
84 make.co
For low-power applications around your home
and yard, professional wind turbine installations
are just too pricey. If all you need is a bit of
juice for LED illumination or a Raspberry Pi
Zero project, paying thousands for a small wind
energy system seems disproportionate. And
for experiments in school, the cost and time
required should be minimal, too — schools are
often strapped for cash. In this article, we’ll show
you how to build your own small wind-power
installation from old bike parts and stuff from
the hardware store. With just a little more than
a breeze, it can provide about 1 watt of power.
That’s enough to charge a small battery, so you’ll
still have power when it’s calm.
This small wind turbine is more of an
experiment to teach you the basics; it won’t
provide you with 100 percent reliable power.
No miracles here! Also, please beware of
strong winds and storms: this machine is not
designed to handle that kind of weather and
would likely disintegrate. You must protect it
from such potential damage, as flying debris
could cause injury.
In contrast to the typical three-blade
commercial wind turbines, we use a vertical
rotor shaft. This eliminates the need for wind
directional tracking and leaves us with a very
simple design. Essentially, it’s just a vertically
mounted bicycle wheel with a hub dynamo. For
rotor blades, we use eight “half-pipes” cut from
cheap plastic (PVC) drain pipe, vertically
attached to the rim.
Our turbine will start spinning as soon as wind
speeds reach about 2 on the Beaufort scale, or
5mph. With a stiff breeze of 20mph or 5 Beaufort
(see the conversion table on page 88), it provides
around 1W of power output (we measured 147mA
at 6.7V).
Build a simple
generator to power
your small projects
from the breeze.
ULRICH SCHMEROLD lives in
Bavaria in the south of Germany
and builds devices for people
with disabilities. He likes to
create projects that get people
excited about physics.
Ulli also made the Micro
Ultrasonic Levitator in Make: Volume 65,
makezine.com/projects/micro-ultrasonic-
levitator, and the Persistence-of-Vision LED
Globe in Make: Volume 53, makezine.com/
projects/persistence-vision-led-globe.
TIME REQUIRED:
1 Day
DIFFICULTY:
Intermediate
COST:
$80–$150
MATERIALS
» Bicycle front wheel with dynamo hub, 28
I bought one new on eBay for €40 but used
ones are ubiquitous in Europe. In the USA you
can score one on eBay, or buy a cheap Shimano
dynamo hub for $50 and install it in an old wheel.
» PVC drain pipe, 4" or 110mm nominal width, 6'
or 2m lengths (2) I used thin-wall pipe but the
exact type doesn’t matter.
» Machine screws, with nuts and large washers
(16) length and diameter depending on your
wheel rim
» Steel water pipe, zinc galvanized, threaded
both ends, 1½" diameter The length (mast
height) will be matched to your local conditions.
» Steel pipe fittings, 1½": end cap (required)
and tee (optional) for water pipe
» Buck-boost voltage converter, DC–DC such as
Mesa #DSN6009 4A. I recommend 30W output
capacity.
» Electrolytic capacitors, 2200µF (2) 12V
minimum
» Full-bridge rectifier 500mA minimum
» Diode, 1N4007
» Heat-shrink tubing or electrical tape
» Wire cables and screw eyes (optional) to guy
out a tall mast
» Concrete, 60lb bag (optional) to set the mast
TOOLS
» Handsaw or jigsaw for cutting thin PVC pipe
» Drill with bits for drilling plastic and metal
» Screwdriver and/or wrench or socket set to fit
your screws/nuts/bolts
» Soldering iron and solder
85
makeprojects.com
PROJECTS: Bike Wheel Wind Turbine
A
BUILD YOUR BIKE WHEEL
WIND TURBINE
Let’s start by building the rotor-and-generator
unit. You’ll be using a mast made from a steel
water pipe, probably secured in the ground using
poured concrete. Check your local requirements
for the foundation and the mast height, and
adjust accordingly. Depending on local conditions,
you may also need to anchor your mast using
wire cables.
1. CUT THE TURBINE BLADES
We used thin-wall PVC drain pipe to make our
turbine blades (Figure
A
). In Germany, where
we live, this stuff is orange; in North America it’s
usually white.
Using a jigsaw, you can cut 4 blades from a
6' or 2m length of pipe (Figure
B
). We need 8
blades in total. Take care to cut the pipe exactly in
the center — ideally, the blades should all be the
same weight.
2. ATTACH BLADES TO GENERATOR
For the generator, we use a bicycle wheel (rim)
fitted with a hub dynamo (Figure
C
). Rims made
from aluminum work best, as they can be drilled
easily. If you’re taking parts from a used bike,
make sure to remove the tire and inner tube, and
any brake discs.
Attach the 8 turbine blades as shown, using
2 screws, nuts, and large washers each, spaced
evenly (try counting the spokes), and centered on
the rim (Figure
D
).
3. MAKE THE MAST
Make the mast from zinc-plated steel water pipe
threaded at both ends (Figure
E
). Drill a 9mm
hole into the end cap and tighten your hub nut
onto the bike wheel’s axle to attach the wheel
to the cap (Figure
F
). Once the mast has been
mounted securely in the ground (!), you can screw
the cap onto the mast.
For erecting the mast, the thread at the
B
86 make.co
Hub dynamo
1
1
IN –
–
2
3
4
2200µF
1N4007
2200µF
2
IN +
+
3
OUT –
4
DC-DC
buck boost
OUT +
other end may come in handy. You can thread a
matching tee piece onto it, and encase the tee in
the concrete block that you’ll pour in the ground.
The concrete should be sufficiently heavy to
both support and anchor the turbine, and must
be fixed firmly in the ground. Then, whenever
a storm comes up, you can simply unscrew
the mast from the concrete block and take the
turbine somewhere safe.
Don’t make the mistake of underestimating the
forces created by winds. They grow proportionally
to the cube (third power) of the wind speed! If
necessary, guy out the mast with wire cables.
4. ASSEMBLE THE ELECTRONICS
Our device is set up for charging a lead-acid
battery using the current generated by the
dynamo (Figure
G
). The hub dynamo produces
alternating current, which we’ll convert to
pulsating direct current using a full-bridge
rectifier. To smooth it out, the pulsating DC is
fed into the two 2200µF (microfarad) electrolytic
capacitors.
The smoothed DC is then passed to a buck-
boost converter (about $10 on eBay) which we’ll
use as a charging regulator. This will convert any
input voltage from 1.25V to 30V into an adjustable,
constant output voltage. We’ll set the converter’s
output to be 0.7 volts above the end charging
voltage of our battery (compensating for the
diode’s forward voltage). The 1N4007 diode is
required to prevent current flowing back from the
battery to the converter.
For example, a 6-volt lead-acid battery has a
charging voltage of 7.2 volts. Adding the diode’s
forward voltage of 0.7V, the converter should be
set to an output voltage of 7.9V.
Your electrical load (whatever’s going to
consume the power, an LED lamp, for instance)
will be connected to the battery’s output. Be
aware that the load must be able to handle the
output voltage set for the converter. While the
generator itself may only be able to provide
a small amount of current, the battery may
output several amps. In case of a short circuit,
the consequences may be dire (fire hazard).
To prevent accidents, you’ll need to safeguard
accordingly whatever circuit you’re connecting to
the battery.
C
F
G
D
E
87
makeprojects.com
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