An Almost Holographic Word Clock

I am a fan of the "Pepper's Ghost". The reflection is probably the easiest way to create a holographic effect. I had the idea to build a clock based on this principle for a long time. I think the clock has become something special, although the projection of the time is based on a technique from around 1860.

I see the whole thing as a proof of concept. The basic idea I had here is clear, so that this clock can also be implemented differently and with other materials. 

It is quite difficult to film the effect because the 3D information is lost.

As you can see, it works even on daylight.

Like all my projects, I start by creating my idea in my computer to check its feasibility.

At the same time, it's easier to experiment with the design and I immediately see how much compromise I have to make with myself between my vision and the implementation.

I use the old version of Google Sketchup8, which is free, to create and visualise. This software is sufficient for my projects

Based on the C.A.D. file, I then create a 2d drawing in Qcad. To make the whole thing understandable to my laser cutter, I import all the parts into Inkscape and add things like the fonts. As with the creation of my 3d drawing, I also use freeware here. 

If you print out the plans and stick them on the plywood, you can certainly saw out the parts with a fret saw.

You can download the cad files here or on my Github

• 4mm plywood
• 3mm black tinted plexiglas
• 1mm transparent plexiglas (for picture frames)
• 16 x M3 12mm Screws
• 4 x M3 40mm Screws
• 8x M3 8mm woodscrews
• black spray paint
• wood paint
• glue and tools

First of all, the lasered parts.

Starting with the side parts. The middle part is glued to the large outer part. After the glue is dry, the interruptions are cut out. The middle part is then used as a cable feed-through. When everything is glued the wires are pulled through

Then the part with an interruption is glued on. After that, this interruption is also cut out.

For the 2 parts with the large opening, glue on the small squares as shown in the photo. These are used to screw the lids onto the openings.

The bottom and top parts are then glued together to form boxes. As you can see in the picture, one part is covered with masking paper. This was used to engrave the texts. Black acrylic paint was then applied to colour the engraving. Then the backing paper is removed.

The part where the clock display comes in later will be painted black.

Then all parts can be screwed together with M3 x 12mm screws and nuts.

I have used a black tinted plexiglass screen as a reflection screen. This works better than a transparent one. Simply insert the screen into the guide provided and you're done. It is best to do this before tightening the side screws completely..

The 1mm plexiglass pane was sprayed with black paint on one side. With the help of a laser cutter, the texts were engraved and the pane cut to size.

The six middle parts were then glued together. I stuck some self-adhesive aluminium tape in the notches to distribute the light better. I also glued the same aluminium tape to the back of the part where the LEDs will be later.

The text Plexiglas plate is first inserted into the upper part of the clock so that the writing can be read correctly from above. Then the block with the holes is placed on top and the 40mm M3 screws are inserted.

• 1 Arduino Nano or equivalent
• 1 RTC-Modul mit DS3231 
• 2 TP223 Touch Sensor Buttons
• 4 74HC595
• 4 ULN2003
• 4 16 Pin Ic Sockets
• 15 240 Ohm Resistors
• 12 470 Ohm Resistors
• 30 White Led´s
• 1 DC Socket
• 1 12V Power Supply min 1A

Don't forget, it's only a prototype :)

I soldered the 4 shift register and the 4 led drivers on a perfboard. For the ULN2003 I used sockets, because I was quite sure that one or the other of these chips would not survive. Spoiler, it did.

I then put the LEDs into the holes and soldered them according to the diagram. Of course, I also used the corresponding resistors. The parts were then attached to the wooden board with hot glue and at the same time everything was insulated as well as possible. 

To set the clock, I decided to use 2 buttons, capacitive buttons. The advantage is that I can install them inside and only the text is on the outside. So I fixed the two TP223 inside with super glue and it works.

The Arduino Nano, the RTC and the shift registers were then glued to a piece of wood with the help of hot glue and everything was wired together. Remember ... Prototype :)

The software is version 1.0. It works without problems, but still needs some cleaning up. I always use different tabs in the Arduino IDE so that my code remains clear.

Just download the code from Github, install it and you're done. No external libraries are used, so everything is easy.

to always have the latest software, it is best to always look at Github https://github.com/awall9999/HoloClock

How to set the clock:

Press the Set button on the left side for 3 seconds. Then the upper part of the display starts to blink. 

With the right Select button, you can now set the minutes.

By pressing the Set button again for 3 seconds, the lower part of the display starts flashing. Now the hours can be set with the help of the Select button.

If the Set button is now pressed for another 3 seconds, the settings are saved and the current time is displayed.

If you do not press any button for 30 seconds while you are in the settings, the system switches back to the current time without saving the settings. 

After the whole wooden construction has been painted with wood paint, only the top and bottom covers need to be fixed with wood screws, then glue on four felt feet and the clock is ready. I hope you like it