The first time I saw a projection clock (a friend had shown me his projection clock,
which he used to project the time on his bedroom ceiling), I knew I could easily build
my own by converting a watch with an LCD display.
I bought a very very ugly watch in a dollar store. So ugly that it really is unwatch
At least it's easy to disassemble...
Disassembling the watch
White on black LCD
The LCD is not usable as-is. To be usable, (1)
light has to be able to
pass through it and (2)
the display has to be black on white (transparent on opaque).
Remove the reflecting background sticker to let the light pass through the LCD:
To get a transparent-on-opaque display, reverse the polarizing filter located on the LCD front side:
See the difference? Left picture: before, Right picure: after.
For more information on LCD technology, read the
Wikipedia LCD page
Reinstalling the LCD
In order to be able to set the time easily, I installed two buttons on a small PCB. Next, I
connected the wires on the watch PCB where the original buttons used to be:
Light and lens
My clock is not very nice to look at, but at least is works. It is build
from various pieces of hardware glued together with hot glue.
The clock in action, projecting the time on my lab wall:
The clock in darkness: