In this Instructable we are going to create a lightbox. This allows you to make dynamic signs or can be used to sketch overlays, great if you are an artist, illustrator or designer!
Step 1: Box Construction
The box is made of a cost-effective and durable pine wood. It is best to simply saw the panels to size and connect them with small nails into the end grain of the adjacent panel. For cutting out the screen panel hole, use a keyhole saw. You will also need to create a small flange for the screen panel to rest on. On the bottom we 3D printed some small hemispheres to act as feet.
The screen panel itself is a custom laser cut translucent acrylic which you can order at a nearest Fablab if you can export a vector drawing.
Step 2: LED Enclosure
We will 3D print an enclosure for the Arduino Pro Mini first, you can download the files from Thingiverse: https://www.thingiverse.com/thing:24611
For powering the Arduino we will use the Lilypad Power Supply for AAA battery, which have great capacity (up to 1000 mAh) and come in rechargeable versions as well. These will last you up to 5 hours at full lighting strength.
You can buy the power supply here:
We created a custom holder for the power supply so you can mount it underneath the Arduino holder, with the power button accessible from the side.
Then on top we designed a custom dome piece to integrate the LEDs in a way so that each one will light a different portion of the screen, and you can individually control the amount of light in every portion of the lightbox.
Download the LED dome here:
Don't assemble the pieces until you have connected all the electronics components.
Step 3: Push Button Interface
Using six push buttons, we can individually control the lighting levels of the LEDs.
You can download our custom designed push button controller casing here: https://www.thingiverse.com/thing:2756857
The Arduino cannot handle high voltages on the input pins so do not forget to connect a 10kOhm pulldown resistor to Ground between the switch and the input pin.
Step 4: Wiring
The Arduino has six pins for (pseudo) analog output using Pulse Width Modulations, pins 3, 5, 6, 9, 10 and 11. Connect these to the LEDs together with a 680 Ohm pullup resistor to limit current flow since the Arduino can handle only up to 40mA per pinout. Use the other pins as digital input pins for the push buttons.
We are using high brightness Power LEDs such as available here: https://www.sparkfun.com/products/11679
You will also need a FTDI breakout board or Arduino Mini USB to upload the software onto the board: https://www.sparkfun.com/products/9873
The six FTDI Basic output pins on the shortest side map directly to the six Arduino bootloading pins on the short side. Most important is to make sure Rx on the FTDI is connected to Tx on the Arduino and vice versa.
Step 5: Software
To write software to control the lighting, you will need to install the Arduino IDE programming environment: https://www.arduino.cc/en/Main/Software
I have written an example program that first runs a test loop through all the LEDs, after which each button will increase the lighting level of its corresponding LED and dims it down after reaching its maximum. See the attached file.
Once all the wiring is completed and the software works to your liking, you can finally assemble the casing using three M3 x 35mm screws.
Close the wooden box, mount the push button controller on the side with double-sided tape and the LED module on the bottom on the inside. Now your lightbox is complete!