3/4” wide slot in the
center — left to right —
all the way through the
cardboard, leaving only
a 1/4” of cardboard on
the left and right sides.
This is where the book
gets its locomotion.
Drill the eye socket
with a 13/16” drill bit. I
used a Forstner bit.
The placement of this
hole is critical so that
the eye mechanism
doesn’t rub on the 600
RPM motor mount.
After a lot of trial and
error, I determined the
best placement is in
the upper left corner of
the cover, 1-1/4” from
the top, and 1” from the spine (where it bends). Refer to
Figure 3.
Drill the plastic eye with a 1/16” drill bit close to the
mold mark all the way through to the other side. I drill
each hole separately (since the eye is hollow) to make
sure they are perfectly aligned. Turn it 90 degrees and drill
close to the end of the ‘stem’ as shown in Figure 4. Place
the two inch piano wire through the first holes creating a
hinge point. Place the eye in the hole and tape the wires
on both sides with filament tape so the eye can look left
to right. Take the FF-030 motor and carefully (gel) super
glue it adjacent to the eye so that it does not interfere
with the 600 RPM motor. Be careful that the super glue
doesn’t enter the motor, or you will have a paperweight
and need to buy a new one. Tie a surgeon’s knot with
the thread (I used Fireline — strong stuff!) onto the end
of the motor shaft and put a tiny spot of gel type super
glue to keep it from slipping. Tie the other end of the
thread to the end of the eye stem. Attach a weak spring
as shown to pull the eye back after the motor has de-energized. This is a lot of commotion to get the eye to
move — but it’s worth it. Color the eye if you want and
hook the motor up for a test. Fiddle with it, restring,
fiddle — done (Figure 5).
Drill the center of the aluminum bar all the way
through with a 3 mm drill bit. Then, turn it 90 degrees
and drill a setscrew hole (#43 drill bit) for the 4-40
setscrew. Tap the setscrew hole and mount the bar on
the 600 RPM motor. You now have a “propeller.”
On each end of the propeller, put some Sugru or
Oogoo for traction. Once dry, mount the motor so that
the propeller is central in the slot. I used a 3D printer to
make the plastic motor mount (the file is at the article
link), but wood or cardboard will also work. Just make
sure it is secure and doesn’t interfere with the eye.
After populating the PCB and attaching all the
external parts (Figure 6), place the PCB inside the box to
the lower left as far as possible. Use foam tape to hold it
in the box. The LM317 regulator is to output the voltage
your sound module needs. Only two resistors are required
to get the proper voltage. The schematic is set up for 2. 9
volts. See the LM317 datasheet for the proper resistors if
September 2015 25
■ FIGURE 6. Populated and wired PCB.
Qty Description
1 L293D dual H-bridge motor driver; Adafruit #807
1 FF-030 motor; All Electronics CAT#DCM-433
1 600 RPM 12V gear motor; Deal Extreme #323578
1 7805 T220 5V regulator; Mouser 595-UA7805CKCT
1 LM317 T220 regulator; Mouser 511-LM317T
2 470 μF 16V electrolytic capacitor
8 1N4148 diode or similar; Mouser 583-1N4148-T
1 100 ohm 1/4W resistor
1 1K 1/4W resistor
1 1.2K 1/4W resistor
1 9V battery clip
1 Small SPST slide switch
1 Sound module (see text)
2" 1/16" piano wire
Fiberglass tape 1/2"
6" Strong thread
1 Weak spring
1 Aluminum bar 1/4" square, 2-1/4" long
1 Small book box, made by Punch Studio #10808,
4-1/2" x 6-1/2" x 1-1/2"; or try Michaels,
Joanne Fabrics, or book stores
(could not find these online!)
1 Double-sided printed circuit board
(see text for file location)
1 20 mm plastic eye
1 Four-way transmitter and receiver; Dx.com #148825
or Amazon 12 VDC 4 CH
Rolling door remote control switch module
controller set
PARTS LIST
• Brown craft paper
• Velcro™
• Foam tape
• Mod Podge or white glue
• Acrylic paint