Moving Eyeball Picture

When you walk into a room, the moving eyeballs follow you.

When your friends watch the eyeballs move, they'll think it's creepy. When you show them the wires and springs on the back side, they'll think you're a genius. Have you ever untangled a garden hose or a balled-up string of holiday lights? The methodical work in untangling — patiently taking one small step at a time — is the approach needed to build this.

How does this work? We make two spring-loaded eyeballs. When resting, the eyeballs look straight ahead. An electric motor attached to each eyeball can turn the eye left or right. A motion sensor on the right causes the motor to turn to the right. A sensor on the left causes them to turn left. Stand in the middle of the picture (no active sensor) and the eyes go to the center.

Parts List

8½" x 11" thin plywood

(2) 3/4" x 1½" wood, 8½" long

(2) 3/4" x 1½" wood, 9½" long

(2) 1" x 1" x 3/4" wooden block

(2) PIR sensor modules, www.parallax.com, #555-28027

(2) Stainless steel extension springs, 0.25 O.D., 2.5" free length, www.smallparts.com, #ESX-0015-02

(2) Relay, 5 VDC DPDT, www.jameco.com, #139977

(1) Slide switch, DPDT, Radio Shack, #275-403A

(2) NPN switching transistors, Radio Shack, #276-1617

(3) Silicon diodes, 200V 1 amp, Radio Shack, #276-1102

(2) 1K-ohm resistors,¼ watt, Radio Shack, #271-1321

(1) 12" red hookup wire, stranded, 22 gauge, Radio Shack, #278-1218

(1) 12" black hookup wire, stranded, 22 gauge, Radio Shack, #278-1218

(4) Screw eyes, size 216½" (small), hardware store

Cedar balls, hardware store

3/8" wiggle eyes, craft store

Perfboard, 2" x 4", Radio Shack, #276-1395

(2) One-cell AA battery holders, Radio Shack, #270-401

(1) Two-cell AA battery holder, Radio Shack, #270-408

(2) 1.5 to 3V DC metal gearmotors, Radio Shack, #273-258

(4) AA batteries

Solder

Glue

Wood screws

Pushpins

Electrical tape

Braided picture hanging wire

Superglue

Double-sided tape

Tools List

Wood saw

Wire wrap tool (see chapter 5 for tips on wire wrapping)

Soldering iron

Drill

1/8", 3/16", 1", and 7/8" drill bits

Screwdriver

Pencil

To get started, you'll need to find or print an 8½ × 11 inch photo or drawing whose eyeballs are at least 2 inches apart, measuring from the center of the left eyeball to the center of the right eyeball. You need at least that much room for the motors and springs.

Next, using the templates on page 39, cut and assemble the five wooden pieces as shown below. Drill the 1-inch holes in the side pieces before attaching them to the plywood. Fasten the pieces together using wood screws. This creates the picture frame.

Place the photo on top of the frame, and poke a pushpin through the center of each eye.

Using the pinholes to identify the center points of the eyeholes, drill two 7/8-inch-diameter holes.

Now, lay the picture facedown and place the frame on top of the picture. Be sure that the bottom of the picture is properly lined up with the bottom of the frame. (If you accidentally match the top of the frame with the bottom of the picture, then the eyeholes in the picture will not match the eyeholes in the frame.) Draw an outline of the circles onto the back of the picture using a pencil.

Cut the eyeholes out of the picture, then place the picture on top of the frame to be certain that the eyeholes match. Once everything matches, place the picture aside until you have finished building the mechanics of this device.

Attach hookup wires (22 gauge) to the motors with solder. (If you are unfamiliar with soldering, see chapter 7.) First, solder a 3-inch-long red wire to the right terminal of each motor. Then solder a 3-inch-long black wire to the left side of each motor. The motors don't care about wire color, but the colors will help you keep track of which wire is which.

Use round wood balls for the eyes. Cedar balls, "for use in storage chests, boxes, garment bags, etc." are available in most hardware and home supply stores. Drill a 3/16-inch hole in one end of each ball, then twist a small screw eye into each ball directly opposite the holes you drilled.

Take two wood blocks (1 × 1 × 3/4 inch) and twist a single small screw eye into an end face (a 1 × 3/4 inch face) on each block as shown.

Turn the frame facedown and center a motor beneath one eyehole. Take a pencil and mark the sides of the motor. Repeat with the other eyehole.

Drill a 1/8-inch hole through each of the four pencil marks.

Push one "eyeball" hole onto the gear of a motor. Attach the spring to the "eyeball" eye screw and — at the other end of the spring — screw the wood block into the frame, screwing through the plywood from the front. The spring should be in slight tension, pulled just beyond the "at rest" position.

Twist braided picture-hanging wire around the motor to hold it in place.

Solder the springs to the screw eyes. Repeat the process with the other spring, eyeball, wood block, and motor.

Turn the picture faceup and glue wiggle eyes to the front of the eyeballs. The wiggle eyes are necessary since they serve as a "stop" to keep the eye from turning too far or spinning around. Make sure that when the wiggle eyes turn left or right they will make contact with the edge of the holes in the plywood.

Next, glue — superglue works well — three AA battery holders (one two-cell and two one-cells) to the inside wall of the frame. Place the two one-cells side by side.

Take a piece of Perfboard and glue the two relays, three diodes, two resistors, and two transistors legs up to the board, as shown. It is not a normal practice to glue all the components with their legs sticking up (like dead bugs). I am doing this so that you can see where the wires are attached. The normal practice (placing the component legs through the Perfboard), creates a more secure attachment with no glue, but it complicates the matter of figuring out which component leg is which. Be sure that the band on the diodes faces the top of the board. The flat part of the transistor should face the bottom of the board. The coil of the relays (two legs that are separated from the other six legs) faces the bottom of the board.

Glue the board to the frame just below the motors.

Now it's time to connect the components. This is not difficult, but it is best to take your time. If any connection goes to the wrong place, or is not well made, the project will fail.

Refer to the schematic diagram on the following page to understand where the connections are made. I have identified each connection with a number. In the photographs, the end of the...