This is an older project, but the electromechanical solution used to create this giant, staring eyeball is worth a peek. [Richard] and [Anton] needed a big, unblinking eyeball that could look in any direction and their solution even provides an adjustable pupil and iris size. Making the pupil dilate or contract on demand is a really nice feature, as well.
The huge fabric sphere is lit from the inside with a light bulb at the center, and the iris and pupil mechanism orbit the bulb like parts of an orrery. By keeping the bulb in the center and orbiting the blue gel (for the iris) and the opaque disk (for the pupil) around the bulb, the eye can appear to gaze in different directions. By adjusting the distance of the disks from the bulb, the size of the iris and pupil can be changed.
A camera system picks out objects (like people) and directs the eye to gaze at them. The system is clever, but the implementation is not perfect. As you can see in the short video embedded below, detection of a person walking by lags badly. Also, there are oscillations present in the motion of the iris and pupil. Still, as a mechanism it’s a beauty.
Inspired by some impressive work on textile flip-bit displays, and with creative steampunk outfits to create for Christmas, [Richard Sewell] had the idea for a flippable magnetic eye in the manner of a flip-dot display. These devices are bistable mechanical displays in which a magnet is suspended above a coil of wire, and “flipped” in orientation under the influence of a magnetic field from the coil.
In [Richard]’s case the eyeball was provided by a magnetic bead with a suitable paint job, and the coil was a hand-wound affair with some extremely neat lacing to keep it all in place. The coil requires about 200 mA to ensure the eye flips, and the job of driving it is performed by a Digispark ATTiny85 board with an LM293 dual H-bridge driver upon which the two bridges are wired in parallel. The whole is mounted in the centre of a charity shop brooch that has been heat-treated to give a suitable aesthetic.
Even when you bear a passing resemblance to the paranoid Auror of the Harry Potter universe, you still really need that wonky and wandering prosthetic eye to really sell that Mad-Eye Moody cosplay, and this one is pretty impressive.
Of course, there’s more to the [daronjay]’s prosthetic peeper than an eBay doll’s eye. There’s the micro-servo that swivels the orb, as well as a Trinket to send the PWM signal and a pocket full of batteries. The fit and finish really tie it together, though, especially considering that it’s made from, well, garbage — a metal food jar lid, a yogurt cup, and the tube of a roll-on antiperspirant. Some brass screws and a leather strap evoke the necessary Potter-verse look, and coupled with what we assume are prosthetic scars, [daronjay] really brings the character to life. We think it would be cool to have the servo eye somehow slaved to the movements of the real eye, with a little randomness thrown in to make it look good.
If you’re wanting to spice up a Jack-o-lantern, why not give it some spooky eyes that will look around? [todbot] shows us how to set this up using an Arduino and 3 servos. His rig uses a hobby servo to control the entire head’s orientation and a smaller servo for each eye’s movement. Their motion is random, but quite convincing. He has them all stuck together with popsicle sticks, but you would probably move the location of the large servo to rotate the entire pumpkin, or whatever other prop you put it all in. You can download the Arduino sketch and give it a try your self. We might suggest building a simple rack and pinion rig to rotate both eyeballs with a single servo.