How to Build a Clock That Projects Time on the Wall

This Instructable shows you how to build a projector clock. This device allows you to project time on the wall. Based on a small LCD alarm clock (not too small, instead, you won't be able to project it and to work on it), this is a good way to display current time.

Step 1: Gather the Parts and Plan

For this Intructable, the main parts you will need:
An LCD clock with a wide screen (mine also display date and temperature)
A magnifying lens (the one used to magnify pictures for example)
A halogen light bulb
A power electric source to feed your light. I used a 12V 60W light bulb, but the power source only provide 6V, dividing by 2 the provided power. A too powerful source would feeding the light would generate too much heat and burn your LCD display.
A fan to evacuate heat generated by the light in the box
A box that you can easily work out (maybe avoid wood since heat could cause it to burn
Other: electric wires, screws, duck tape, glue and welding iron
Your first and most delicate work is to modify the LCD

Step 2: Modify the Display

Usually, LCD displays used in small clock are setup to be shown from the front. Our device needs to have the light source from behind, in transparence. So we need to modify the screen to let the light go through the display. However, the same could be used in reflection but in this case, the luminosity would be lower:
A typical LCD display is composed as seen on the picture.
The glass screen is placed between 2 polarized filters that orientates the light and allows for the time to be display in black on white.

To let the light go through the display, you will first need to remove the reflecting bottom of the screen. To get an inverted display (white on black), you will then need to remove the second polarized filtered and turn it by 90° clockwork or counter-clockwork, no mater. These two steps are quite difficult since the filter and reflecting surface are strongly stick together and very thin. When removing the filter from the screen, be careful not to damage them.

Step 3: Modify the Clock

In order to change the time from outside the final box, you will need to modify the clock so that controls are accessible. Wire some cables to replace the existing button on the circuit board. Weld the button respecting the existing layout

Step 4: Setting the Optic

The principle is to experiment the setting of your optic depending on the magnifying lens you have found. Take your light source and fix it firmly. Install a transparent object and try to project it at the distance you think your clock will be installed. You will find the distance you need from the screen to the lens in the final setup.
Be careful, your image will be inverted, so you will also need to reverse the LCD screen bottom-up and left to right.
Chose a light bulb that will cover the full width of the screen at the chosen distance. This could be a problem with some much focused light.

After finding the right distance, install the LCD screen and lens on supports to maintain them. I built an adjustable rail to be able to modify the focus depending on the distance to the wall to have a clear image. Of course you can build a more advance version of the optic, with a zoom but I am not an expert.

Step 5: Installing the Devices in the Box

Once your rail and optic are ready, install them into the box. Drill a hole to let the light out of the box. Drill two other holes for the fresh air to come in and the hot one to go out. Try as much as possible to have a clear flow of air in the box by forcing the air to flow on the LCD and then on the light bulb. Always let the flow go from lower to higher temperature so that hot air from the bulb in our case does not heat the LCD.

Step 6: Testing

Your device should be complete now and your can test is. Be careful with the light bulb and your power source. Try and project your clock on walls. Be sure to stay parallel to it if you want your image to have the right shape. Depending on the power of the source, you could be able to project time in different ambient light conditions.