Perfect prop for a spooky Halloween party or just to scare your mates. We've put together the Raspberry Pi powered moving eye picture which can be controlled independently or using the Raspberry Pi camera. You will need
- A painting or print of someone. The spookier the better. We chose John Quincy Adams, 6th President of the United States of America.
- A box picture frame to fit your chosen print. We chose the 40cm by 50cm Ribba frame from Ikea as it has a thick frame and room behind for wiring and parts.
- A Raspberry Pi.
- A PicoBorg Reverse motor controller.
- A pair of magnets, we used 4mm by 12.5mm cylindrical shaped neodymium magnets from first4magnets.
- Thin wire, the higher current rating the better. We used Kynar wrapping wire because we had some lying around.
- Some hookup wire for connecting the coils and battery to the PicoBorg Reverse.
- Two tubes to wrap the thin wire around. This could be pens, or similar plastic cylinders. We used two small pipettes again because we had them spare.
- Sticky tape. Lots of sticky tape.
- Two resistors. We used 2.4 Ohm resistors, but this depends on your choice of wire. Try and use resistors that have a higher wattage rating eg. 1/2 watt.
- A small amount of thick wire, we used a piece of aluminium wire approximately 3mm in diameter.
- A couple of small squares of card. We used business cards.
- Something flat and low friction for the card to slide along. We used empty integrated circuit tube packaging.
- Paint to match the eye colour, so white or magnolia or something. We're not artists ;)
- Sharp knife
- Soldering iron
- Wire cutters
- PVA glue.
- A Raspberry Pi camera.
- 10 AA batteries.
A BattBorg power regulator
Step 1: Cut Out the Eyes of Your Print
Carefully cut the eyes out of your chosen print. This can be quite fiddly so take your time, making sure to cut them as neatly as possible. Don't throw them away as we will need them later! Put safely to one side.
Step 2: Colour Around the Eyes
Using a black Sharpie colour in around where you have just cut out the eyes. Although it changes the look of the portrait, it does give a nice evil look.
Step 3: Stick the Eyes Onto Your Card
The eyes you saved from the first step need to be stuck onto your card. We used a business card as they are quite thick and sturdy.
Use the eyeholes from the picture to line up where your eyes should be stuck on the card. They need to be central, and approximately the right distance apart. If they're not, your spooky picture could end up being a herp-a-derp picture.
Step 4: Paint Around the Eyes
Using some paint, colour in around the eyes on the card so it colour matches the whites of the eyes from the portrait. I'm no artist and all we seemed to have laying around was magnolia wall paint and we added a red biro just to up the evil rating.
Step 5: Put the Picture in the Frame
Put the picture in the frame. Ikea have a range of frames which are cheap and have enough room behind the picture to place your wiring and Raspberry Pi.
Step 6: Place the Guide Rails
Line up the guide rails on the back of the portrait. This is an important step to ensure your eyes move accurately left and right inline with the eye cutouts.
Place the business card with the eyes onto the portrait and look at the front. Move them gently left and right to work out the furthest the card should be able to move. Think of the black rails as a fence to stop the eyes from going too far. Once you're happy with the position of the card and the rails, stick the rails down onto the back of the portrait with tape. Do not stick the card down as it needs to slide freely.
Step 7: Wrap the Wire Around the Tubes
Wrap the wire tightly around the tubes to form a coil. We used two small pipettes as we had a couple spare.
The coil was wrapped tightly from one end to the other then back again over the first layer. We ended up with approximately 4 layers of wire. Use a small amount of tape to keep the coil nice and tight.
Leave a small amount of wire dangling at the ends of the coil. This is to attach the resistors and wires to the PicoBorg Reverse later.
Step 8: Solder the Resistors and Wires
Solder a resistor onto one side of each coil. This limits how much current will flow through the coil, so you don't burn it out. One coil should be connected to M1+ and M1- on the PicoBorg Reverse, the other coil should be connected to M2+ and M2-. Don't worry which way around you get these, as we can change direction in the software later.
The resistor should be low resistance but high wattage. We used 2.4 Ohm 1 Watt resistors.
Step 9: Position the Magnets and Coils
This part can take a little bit of time to get right as the magnets and coils need to be positioned correctly. The magnet needs to be in the centre of the coil, but not touching the tube.
To make the eyes move from left to right the magnet needs to be attached to the card via the short piece of thick aluminium wire. The coils need to be attached to the picture. It's important that the coil and magnet don't touch.
When the card is all the way to the left as you look at it, the right hand magnet should be roughly 1mm into the right hand coil. And visa versa for when the card is all the way to the right.
Be sure the card with the eyes moves freely. When attaching the aluminium wire and the magnets to the card, try to use as little aluminium and tape as possible to keep the weight down.
When you are happy with the position of the magnets, attach them to the eye card.
Step 10: Stick the Coils Onto the Picture
With some sticky tape, stick down the coils and the resistor to the picture. Lift the resistors off the picture so that if it gets hot they don't burn the picture. (It will get hot if the coils are activated for too long).
Step 11: Secure the Eyes in Position
Secure the business card with the eyes, by sticking another business card over the top and attaching this to the guide rails. Be sure the eyes can freely move left and right, and that it doesn't get caught on anything.
Step 12: Wire Up the PicoBorg Reverse
Attach the power to the PicoBorg Reverse and the communications cables which come with the PicoBorg Reverse to the Raspberry Pi. Also if you are using it, attach the Raspberry Pi camera to the Raspberry Pi.
Step 13: Boot the Raspberry Pi and Run the Software
At this point, all the mechanical steps of the moving eye picture are complete. We have not yet finished writing the instructions for using the PicoBorg Reverse software for this project. We're hoping to complete this in the next few days and add the steps on here.
If you would like extra help, please message us on here in the comments, or head over to our forum which can be found at: http://www.piborg.org/forum