Darkbeam: The Smart Nighttime Projector (v3.1)

What is Darkbeam?

Darkbeam is a little projector box with WiFi. Put it next to your bed to project the date and time to your ceiling or wall at night. You can also project any other content you like, since it uses a 128x64 graphics display.

Note: It's not good for day-time projection. The OLED is simply not bright enough for that.

IMPORTANT: Read printing instruction before printing.

Non-printable Parts Required

• A lightweight Canon EF mount or FD mount 50mm lens
  • I have tested both
    • Canon EF 50 mm/1.8 II
    • Travenar 50mm f/1.7 (Canon FD mount)
  • You should be able to get a used FD lens from eBay below 40 Euros
  • Make sure to have a wide aperture (f < 2.0) to get a bright enough projection
• M5Stack ATOM Lite 
  • An affordable microcontroller with WiFi
  • ~7 Euros
• SSD1306 OLED Display (128x64 pixels, 0.96 inches)
  • ~8 Euros
• Four wires
• Angled 2.54mm pin headers
• Heat shrink

Tools Required

• Soldering iron + solder
• Super glue (cyanoacrylate)
• Hot glue gun

Printing Instructions

General instructions

• Almost all parts can be printed at standard layer height of 0.2mm or 0.16mm and standard settings
• I recommend to use “ironing” on all top surfaces to get a smooth finish
• Don't use supports
• Use fine layer height (0.1mm) for the bayonet when using the EF mount

Steps

• For EF mount:
  • First print the bayonet at high layer resolution (lens-mount-bayonet.stl)
    • This part will be inserted into the lens mount mid-print!
  • Then print the lens-mount-lensside-Canon-EF.stl half-way. This video explains how you can add a pause to your print and how to insert the bayonet.
    • Let me know if this is not working for you. I can provide an alternative model where you glue the bayonet instead of fusing it
• For FD mount:
  • No special procedure, just print the lens-mount-lensside-Canon-FD.stl with standard settings
• Then print all the other parts with standard settings in arbitrary order

Assembly Instructions

NOTE: The video features only Canon EF mount lenses, but now you can also use FD mount lenses which are cheaper and come with an easier-to-print mount.

Software

There are two different ways to use Darkbeam:

1. With ESPHome (for standalone use or integrated with Home Assistant)
2. With micropython (for streaming arbitrary image/video content from a server)

For the example firmware files and more details check out https://github.com/philipp-fischer/darkbeam

Usage

Once Darkbeam is assembled and the firmware is installed, you'll want to set it up.

• Pick a location to place Darkbeam (e.g. nightstand)
• Pick a location to project to (wall or ceiling)
• Initial focusing
  • Adjust lens mount on the large thread until you have the focus about right.
• Adjust the lens-shift and rotation to match the desired orientation
  • Sliding the knob on the back of the display box left and right can compensate for some amount of perspective distortions. To move the projection to the left, move the knob to the right
  • Turn the knob to orient the displayed text upright
• Final focusing
  • Now use the manual focus of the camera lens itself to finetune the focus until you can see the individual pixels

Attribution

Thanks to @Loudifier_25336 for designing an EF lens mount. The lens mount for Darkbeam is based on their creation here:

https://www.printables.com/model/5210-efef-s-to-ef-m-macro-adapter