This is an academic write-up of my Lithophane Lamp. Adjustments have also been made to ensure it fits within a MakerBot build volume.
This is a hidden picture lamp, utilizing lithophanes. Note: this does not use an actual hidden picture! It is a piece of plastic where the thicker spots absorb more light (black) and the thinner spots absorb less light (white) giving a photo effect.
The support structure
The support structure was designed in FreeCAD. It's a relatively simple support structure. If you decide to not follow the process exactly as I defined (perhaps you want thinner/thicker lithophanes) then you may want to redesign the support structure. An alternative to redesigning the support structure would be to adjust the scale of the support I designed in your slicer tool.
The overall objective is to design and print a lithophane lamp and control the illumination with a WiFi connected device.
Sub-objectives are to: (1) understand the basics of how the image is produced, (2) understand the basics of constructing a simple structure, (3) get exposure to utilizing a transistor, (4) get exposure to the basics of a circuit, (5) get exposure the basics of programming and setting up a website.
This project is best suited for high school aged students. While the steps could be accomplished by adolescent students, older students will better absorb the concepts and have a higher likelihood of successful deviation.
None of these things are required, however, having taken some or all of these courses would allow for successful deviation from the listed steps:
(1) Basic Circuits
(2) Computer Science
(3) Technical Drawing (CAD)
Steps (Lithophane Lamp)
(1) Use this website to make the lithophanes: (Note: You may have to use Chrome, IE sometimes fails.) Here is the exact process I used:
- Picture Shape: Square
- Picture Orientation: Horizontal
- Pane Size: Large
- Invert Colors: Checked
- Include Hole: No
- Hole Diameter: [Doesn't apply]
- Layer Height: 0.2
- Number of Layers: 20
- Height from 4.4mm to 3.2mm
(2) Print your lithophanes and scale to 76 x 76 x 3.2 mm. (Change the print height in your slicer and the x, y dimensions should be correct.) Printing anywhere 0.1mm - 0.2mm is great with 100% infill.
(3) I used ABS; the LEDs get the structure up to 50-60C. PLA will work by limiting the LED brightness if it gets much hotter.
(4) If you normally use "ABS juice", use a glue stick this time. Cleaning the residual slurry off the flat side will be unsightly (as it is the outside part of the lithophane.)
(5) Print the lithophane support structure at your standard settings with no support required. 100% infill is not required for these.
(6) The LED tower is glued to the base with something strong such as J-B Weld.
(7) The shown LED strip is here.
Here is a how-to video if you need.
Two versions can be constructed. A single level, or two levels. Just print the appropriate light holder STL.
Steps (WiFi LED Driver - Not Required)
Materials (for exact copy; substitutes would surely work):
(1) LED Strip + it's power supply (link above)
(2) Particle Photon
(3) D24V10F5 Voltage Regulator
(4) 3 ZTX689B NPN BJTs
I highly recommend these transistors over TIP31s that people typically buy. These have a very low saturation current, and they support this power application sufficiently.
(5) 3 resistors ~330 ohms (driving this with 3.3V PWMs signals from the Photon)
(6) (Optional - Highly Recommended) Heatsinks for the BJTs
Power transistors get hot, and should be used with heatsinks (even TIP31s). With the heatsinks, the transistors measure at ~45C passing 0.4A each.
(7) (Optional) Breadboard, Heat-shrink Tubing, Solder
(8) (Optional) Web server for Photon to talk to (I'm using a BeagleBone Black.)
(9) WiFi Device (Cell Phone, Computer, iPad, etc)
This will enable you to control the LED strip with your WiFi connected devices, such as your cell phone. Here is a demonstration. If you skipped these steps, you can control the LEDs with the included remote control.
The final result should be a WiFi driven Lithophane Lamp which your friends will demand you reproduce for them!