This project is how to build a haunted dolls house bed.
It works on the same principal as Pepper's ghost (https://en.wikipedia.org/wiki/Pepper%27s_ghost) but instead of using a bright light to illuminate a physical object, it uses a TFT screen to create a ghost that can move around and change.
The effect can be been in a lit room but looks excellent in an unlit room of a doll house.
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The most obscure parts for this build are a car reversing monitor and a four poster bed for a doll house.
I got a 4.3" monitor for £8 (approx $12) off eBay, the bed came as part of a 2nd hand dolls house.
In all you will also need:
- Arduino Pro Mini 5v
- 1kΩ resistor
- 470Ω resistor
- Female pin headers
- Cheap picture frame (i.e. from a Dollarstore or Poundland)
- Thin wire
- Car reversing monitor
- Four poster dolls house bed
And these are the tools you'll need:
- Soldering iron
- 5v FTDI cable
- Glass cutter
Remove the stand from the back of the frame, it should just pop out.
Remove the back of the screen, be very careful you don't damage any ribbon cables.
Cut the video connectors off the screen.
We're going to be using the Arduino TV Out library to control the screen which means we need to build the very simply circuit shown on this page:
The important thing to notice is that the 1kΩ resistor goes to pin 9 on the Arduino and the 470Ω to pin 7.
Connect the cables from the screen to our circuit:
- The ground wire (black) should go to one of the ground pins on the Arduino.
- The power wire (red) should go to the Vin pin on the Arduino.
- The signal wire (yellow or white) should go to the resistors on the circuit board.
Run two more wires to power the screen and Arduino:
- One wire should go to Vin on the Arduino.
- One should go to one of the ground pins on the Arduino.
The completed project will take 12v.
At this point you will be able to test that your circuit is working correctly.
Upload the ghost.ino sketch to your Arduino. You'll need to have install the TV Out library for it to compile.
Unplug your Arduino from your computer and power the screen with 12v.
If everything is working you should see a ghost bouncing around the screen.
If you want to change your ghostly image you can use the covert.py Python program that I've supplied to convert most image formats into the correct format for the TV Out library.
Assuming you already have Python installed just type:
python convert.py image_filename
into your terminal.
Find the largest free space inside the screen and cut a the cardboard so that it fits in the available space. This cardboard is used to prevent the Arduino circuit from shorting out against the screen.
Using the Dremel cut two slots in the back of the screen. These should be spaced so that the pin headers on our circuit board will fit through and should be positioned over the top of the cardboard we just cut.
Carefully drill four pairs of holes into the side of the screen and feed some wire through.
Reassemble the screen with the Arduino circuit in place
Flip the bed upside down and use the wire to attach the screen to the underside of the top of the bed.
Dismantle your cheap picture frame as all you want is the glass.
Use the glass cutter to trim the glass so that it will fit between the posts of the bed.
If you don't have a glass cutter, or don't feel happy working with glass then you can use a sheet of plastic instead but try to find the clearest piece of plastic you can.
Place the glass in between the pillars of the bad and angle it at as close to a 45* angle as you can.
With the bed still upside down and using plenty of glue, stick the glass screen in place. I used hot glue but any strong glue should work.
Once the glue has set flip the bed up the right way.
Using as little glue as possible, stick the glass to the sides of the bed.
Plug your screen in, if everything is working you should now see a ghostly figure floating over the bed.