DIY

Homemade Wind Station

article image
PHOTO: T.J. BYERS
When all is assembled, your wind instruments will look like this.

Selecting the right spot for a windplant–or even just
choosing a suitably sized generator –can be
nearly impossible unless you know how much wind to expect
and from what direction it’s likely to come. After all, the
amount of wattage that such a powerplant will produce is
actually related to the square of the wind
velocity and thus a small difference in speed can make
a big change in the amount of electricity generated. (For
example, a 15-MPH breeze will actually yield about
twice the energy that a 10-MPH puff does.)

Of course, there are a number of commercial
wind-monitoring systems available. Many of them
are excellent products, but they tend to be quite
expensive. In fact, I was pretty reluctant to spend the
$100 or more (in some cases much more) necessary to buy a
quality cup anemometer, so I decided to build a homemade wind station myself–both the anemometer and wind vane.

The two parts of the system have many similarities in their
construction, and can both be mounted on the same PVC pipe
stand. The anemometer,
however, is just a bit more complicated than the
wind vane, so let’s start with it.

The Motor/Generator

The heart of my homemade anemometer is a small electric
motor–with permanent magnets and windings–that
can also operate as a generator. It’s often possible to
remove excellent examples of anemometer-sized motor/
generators a from children’s toys–after getting the
permission of the youngster in question, of
course–but the Radio Shack unit I’ve specified
happens to fit perfectly the PVC pipe parts we’ll be using.

To turn the little motor into a generator that’ll give a
readout proportional to wind speed, all you need to do is
give the powerplant “wings” to catch the breeze. A DC
ammeter will then measure the motor’s output, and you can
calibrate the gauge to read in MPH.

The Housing

The powerplant specified in the materials list will fit
snugly within a 3/4″ to 1/2″ Schedule 40 PVC cup reducer…
but you’ll have to cut notches in the fitting’s seat to
accommodate the wire tabs which emerge from the
motor/generator’s bottom. A 3/4″ Schedule 40 PVC coupling
can then be slipped over the motor and cup
reducer, enclosing the rest of the generator. Now grind the
tips of the eight-sided plastic fitting down until they’re
flush with the 3/4″ coupler, cement the unit into the PVC
housing with all-purpose glue, and seal the assembly with
silicone adhesive. Becareful that you don’t get any
of the caulking on the axle.

To keep water from leaking in around the motor/generator’s
shaft, cut a 1/4″-diameter washer from a piece of felt, and
poke a hole in the center of the material with a needle.
Slip the washer over the generator’s shaft, and
then oil it with sewing machine lubricant. (Be
sure you don’t get any oil on the shaft tip! )

The Spinner Assembly

Two bisected ping-pong balls serve as the “sails” that spin
the homemade wind gauge. After much experimentation, I’ve
found that the spheres are most easily divided by cutting
around the seam with a razor knife. Don’t puncture the
surface, just make a progressively deeper cut until you can
split the ball by squeezing it gently.

The hemispherical sails are connected to the central
spinner by 3 1/2″-long sections of coat hanger. To mount
the rod into each cup, snip two notches in the lip of the
plastic–directly opposite each other–and glue
the coat hanger in place using general-purpose cement.

While the adhesive is setting, locate a 1 1/2″-diameter,
2 1/2″-long prescription bottle, and drill four 7/64″
holes–spaced at 90° intervals–into the
sides of the vial, at points just above the bottom. Then
bore a 5/64″ hole exactly in the center of the bottle’s
base, using the bottom’s casting “tit” as a guide for
positioning the drill bit.

Next, turn the vial upright and insert a “sail
arm” into each of the 7/64″ holes. Position the ping-pong
ball halves so that they’ll catch the wind (either
clockwise or counterclockwise motion will do), and set them
so that each one is an equal distance from the bottle but
doesn’t obstruct the central 5/64″ hole.

Epoxy will hold the coat hangers in place within the
container but, before you pour the adhesive into the vial,
you should place your 5/64″ drill bit (coated lightly with
oil so the epoxy won’t stick to it ) into the
5/64″ hole to keep a central opening for the
motor/generator’s shaft. I just drilled a corresponding
hole in the bottle’s top–to keep the bit lined
up–mixed up a small amount of fast-setting epoxy,
poured it in 1/4″ deep, and then slipped the lid into
position to support the “far end” of the drill. After five
minutes of setting time, I was able to gently remove the
drill and put the assembly aside to finish drying
completely. On the morning after pouring the epoxy, you can
attach the spinner to the motor. Just slip the prescription
bottle unit over the generator’s shaft–the fit should
be snug–and test the device for balance and
squareness by spinning it. Slide it all the way down on the
motor’s shaft, apply a drop of cyanoacrylate glue (Crazy
Glue, Permabond, or Eastman 910, for example) to the
tip of the shaft, and then slip the vial back out
until it’s flush with the end of the shaft.

Wire It Up

Solder a 1,000 (1K) ohm calibration potentiometer across
the 0-1 milliampere meter’s terminals using only the
central wiper terminal (the lone one, opposite the other
two) and either of the remaining connectors. Now wrap each
wire from the “sender” around a terminal on the meter
(don’t solder yet!). When that’s done, turn the
potentiometer, using a small screwdriver, all the way in
one direction and give the sender a spin. If the needle
fails to move, turn the control all the way in the
other direction and repeat the test. (If the meter
goes in the wrong direction, switch the wires on the meter
terminals.) A healthy spin should now produce about a
half-scale reading. If it does so, you can complete the
construction by soldering the wires to the terminals on the
meter.

Anemometer Calibration

A well-made commercial anemometer will provide you with an
extremely accurate basis for calibrating your
device, but you can get pretty close using your car’s
speedometer. Temporarily mount the sender atop a five-foot
piece of plastic pipe–no glue is necessary at this
point–and have a friend pilot the family carriage
while you hold the spinner up in the wind. Have your driver
proceed down a level (and deserted) section of rode at 25
MPH so that you can adjust the control to produce a meter
reading of “1.” Make a couple of passes back and forth to
compensate for the wind direction, as well as your car’s
streamlining and speed inaccuracy. Then have your assistant
drive the car at 20, 15, 10, and 5 MPH so you can note
those readings. (If you prefer, you can later make
a new faceplate for the meter which reads in the correct
MPH.) And, once you’ve mounted the meter in the center of a
suitable board, your anemometer will be complete.

Wind Vane Construction

The weather vane portion of my home-made wind-monitoring
center consists of a “sail” which is connected to a rotary
switch that, in turn, is wired to a series of lamps
arranged in a circle. As the wind direction changes, the
shaft will rotate and touch different contacts, thereby
lighting corresponding lamps until it settles on the
new wind direction.

The mechanical components of the instrument are quite
similar to those used in the building of the anemometer: a
coat hanger, a plastic vial, and PVC pipe parts. The
wind-catching portions of the instrument, however, are
formed from steel rather than ping-pong balls. The best
free source of suitable metal is a discarded
steel beverage can. (Most drink cans are now made
of aluminum and won’t work. However, all canned teas come
in steel containers as do some colas.)

Using an opener, remove the top and bottom of the can and
then cut along its seam with a pair of tinsnips. Before you
attempt to flatten the metal, snip away the “lips” where
the lids were joined to the can’s body. The operation may
involve removing as much as half an inch from each end of
the container, because of the tapers rolled into the can’s
sides.

At this point you’ll notice that the steel still
doesn’t want to stay flat. Don’t despair, the problem
will be remedied in short order. First, use the tinsnips to
cut the metal into the shape of an arrow tail. Then,
in order to strengthen the flimsy sheet, form three
lengthwise ridges in the piece by laying the vane on a
length of coat hanger and sliding a short section of 2 X 2
along the metal directly above the wire. The pressure will
create grooves in the tailpiece.

Now cut a straight section of coat hanger 12 inches in
length, and remove its paint with sandpaper. Once that’s
done, fasten the support rod into the center groove in the
vane, using acid core solder and a torch. (Never
solder in an area with inadequate ventilation, and
always avoid breathing the fumes formed while
heating the metal, solder, and flux!)

In order to avoid having the tail’s weight put lateral
pressure on the bearing, you’ll need to build a
counterbalance. I made one by filling the decorative
endpiece of a curtain rod with solder and plunging a short
piece of coat hanger into the still-molten lead. (The wire
must, of course, be sanded and timed if it’s to bond to the
lead correctly.) A number of other approaches could also be
used to provide the needed counterweighting, including
welding nuts or washers to the coat hanger section.

Whatever approach you use, the tail and counterweight will
have to be mounted into the housing–which is formed
from another 1 1/2′ X 2 1/2″ prescription vial–to
establish perfect balance. Drill two 7/64″ holes (one on
each aide of the bottle) to accept the “free” ends of the
coat hanger pieces, and balance the rods in the openings,
adjusting the length of the counterweight “stem” to level
the assembly.

The switch shaft will be set into the pill bottle in much
the same fashion that the motor shaft was mounted for the
anemometer. Drill a 15/64″ hole in the casting tit on the
bottle’s bottom, place the oil-coated drill bit into
position, and pour the epoxy in around it to a depth
sufficient to secure the tail and counter-weight rods.

Mounting the Switch

I’ve found 14- or 16-wire telephone cable to be the easiest
material to use for wiring the rotary switch. Solder one
wire to each of the 13 terminals on the bottom of the
switch, but be sure to jot down the colors, and
their respective terminal numbers, as you go.

Now mount the switch in a 3/4′ Schedule 40 PVC pipe
coupler. Unfortunately, the oval shape of the switchplate
is slightly larger than the coupler’s inside diameter, so
you’ll have to cut (with a hacksaw) a 3/8″-wide, 5/8″-deep
notch on each side of the coupler to provide clearance.
Furthermore, to reduce the friction of rotation, you should
remove the index ball located under the switch’s metal
mounting bracket.

Unit Assembly

Once you’ve finished the wiring and mounting and have
allowed the epoxy to set overnight, you can begin putting
the pieces together by threading the cable into the
coupling and slipping the switch into its grooves. When the
device is seated, check to see that the shaft is aligned
accurately, or wobbling and sticking will result.

To seal the housing, wrap electrical tape around the upper
(cutaway) portion of the coupler, and fill the recesses
with silicone sealant to protect the contacts from
moisture. (Don’t force the adhesive into the
switch holes or you’ll run the risk of hindering the unit’s
operation.) While you have the caulk in hand, seal the
other end of the switch housing, but avoid getting any
material on the shaft or bearing.

Then, to complete the vane assembly, slide the
vial/tail/counterbalance body over the switch shaft and
down until it contacts the parts inside. Then place a drop
of cyanoacrylate glue on the end of the shaft, slip the
vial back out until it’s flush with the shaft end, and
allow the adhesive to dry. 

The Indicator

Twelve lamps are arranged in a circle–like the hours
on a clock–to serve as the wind direction readout.
Although you could use a number of different kinds of
lamps, I’ve specified readily available units that come
with attached leads to facilitate wiring.

Drill a dozen holes (in a circle around the wind velocity
meter) large enough to accommodate the bulbs, slip the
lamps into the openings, and connect one lead from each
bulb to the power source. Then solder the other wire from
each light to one of the switch’s contacts. Refer to the
color code chart (you did make one, didn’t you?), and
connect the lamps, sequentially, to the switch contacts. It
doesn’t matter where you start, but you must
maintain the proper order. Finally, attach the wiper lead
from the switch to one leg of your power supply.

The wind vane can be mounted by teeing a second vertical
piece of pipe from the anemometer mount (as shown in the
photo), but be sure to set it a foot or so above
the anemometer to avoid having one device interfere with
the wind flow to the other.

Before you glue the wind vane atop the 3/4″ PVC
stand, you must orient the assembly. First turn the vane so
it’s pointing due north. Then just have someone check the
display to see which lamp is lit. Simply rotate the switch
housing (without turning the vane itself) until the north
lamp lights up, and then glue the coupler to the pipe in
that position.

Putting the Wind Monitors to Work

Move your wind vane and anemometer to different locations
periodically, and record–on a regular basis–the
readings you get at each site. You should note the speed
and direction of the wind at least twice a day aver a
two-week period.

Start by checking hilltops, and then move on to fields that
are unobstructed by trees, hills, or buildings. (If the
equipment is set farther than 100 feet from the meter and
lamps, use at least 18-gauge wire to prevent line
losses.) In general, a good windplant site will have
breezes of over 10 MPH three times per week or more. But
keep in mind that one 20-MPH blow will produce more power
than three 10-MPH zephyrs (remember the “square law” of
wind power?).

If you keep careful records, your wind-energy-measuring
equipment will help you to make the best possible decisions
about where you should put a windplant and how
large a generator you actually need. Furthermore, I think
you’ll find that the attention the device will cause you to
pay to the weather will help you to make innumerable
other wise choices–concerning such things as
where to put the chicken coop or where to locate trees for
a windbreak–around your home.


List of Materials

ANEMOMETER

(1) motor (Radio Shack No.273-213)
(1) 0-1 milliampere meter (R.S. No. 270-1752)
(1) 1,000 (1 K) ohm control (R.S. No. 271-333)
(1) 3/4″to 1/2″Schedule 40 PVC cup reducer
(1) 3/4″ Schedule 40 PVC coupling
(1) coat hanger
(2) ping-pong (table tennis) balls
(1) 1-1/2″-diameter, 2-1/2″-deep prescription bottle
fastsetting epoxy 3/4″ Schedule 40 PVC or steel pipe hookup
wire silicone seal general-purpose cement felt washer
cyanoacrylate glue

WIND VANE

(12) 6-volt lamps (R.S. No. 272-1144)
(1) 6-volt transformer (A.S. 273-1384)
(1) 12-position rotary switch (R.S. No. 275-1385)
(1) 1-1/2″-diameter, 2-1/2″deep prescription bottle
(1) 3/4″ Schedule 40 PVC coupling
(1) coat hanger
(t) steel beverage can
(t) 3/4″Schedule
40 PVC “T”
14 or 16-strand hookup wire
fast-setting epoxy
50/50 solder
silicone seal
electrical tape
cyanoacrylate glue