DIY Pocket Projector Design

A simple pocket-sized projector utilizing an Arduino

Similar projects worth following
I find the fact that I can hold a magnifying glass at a certain distance from a brightly lit image and a wall and see a focused image to be incredibly cool. I also find Heads Up Displays to be incredibly cool and useful. To have information seemingly projected onto the environment before you allows for one to be focused on the information and the environment simultaneously. But if I wanted to build a HUD, I needed a projector. And I didn’t want to spend the money on a commercial pocket-sized projector.

How HUDs Work

HUDs work by using a projector to project an image onto a calculated, curved glass surface, focusing the image projected onto it at infinity from the perspective of the viewer. This allows, for example, a pilot, to see speed, bank angle, altitude, heading, etc. seemingly projected onto the environment outside of the aircraft. Instead of having to shift his focus from outside the window to either an image projected onto the window or instruments on the dash, the information appears focused at the same distance as the environment, allowing simultaneous focus.

How This Projector Works

There are many different types of projectors, some types working wildly different from others. This one works by using a high-power LED to backlight a small, fair resolution color LCD. The bright image from this LCD is then shone through a convex lens, focusing the image. The trick here is having a high enough resolution LCD and a bright enough LED. As an image is magnified, it gets dimmer due to its photon density decreasing. If you have 100 cows on a one acre plot of land, the cows are tightly packed. One cow per 100th of an acre. Now, if you put those 100 cows on 1,000 acres of land, you have one cow per ten acres. The same applies here for photons. The image is magnified, therefore dimmer. This requires a much brighter image to begin with, to make up for the loss when magnified. To use a HUD in daylight, it must be incredibly bright. If our image is bright to begin with, and then the image is shrunk, it will be even brighter, like starting with the 1,000 acre plot of land with 100 cows. So, super bright image made brighter by shrinking. Long story short, Arduino Nano controls inputs and outputs to the LED and LCD. LED backlights the LCD, the image focusing through a convex lens, projecting onto a small piece of glass in this case, reflecting back into the user’s eye.

Why an LCD?

LCDs (Liquid Crystal Display) work by blocking light at different levels. If a given pixel is black, the LCD will block, to the best of its ability, all light passing through. If a given pixel is white, then it will allow all light to pass through. LCDs are fairly cheap nowadays, at least until one gets into the crazy-high resolution or large display area LCDs.

Zip Archive - 35.27 kB - 09/12/2020 at 18:38


  • 1
    The Electronic Components

    For this project we’re going to need nine different types of components, along with a heat sink of some sort. Three different types of resistors are needed. I went with 1W ratings for each resistor. One 2512 130Ω surface mount resistor, one 2512 2.2kΩ surface mount resistor, and two 2512 200Ω surface mount resistors. All parts are linked in the “Bill of Materials” section. One 2.4in TFT 240×320 SPI LCD is needed, along with a Cree 6500K SMD high-power LED. One BD 139-16 and one BC 547 transistors are needed. Two 3-position 200mA, 30V slide switch is needed in order to turn the device on as well as switch brightness levels. A zero-insertion force 1mm LCD port is needed as well. One Arduino will be needed to control the assembly, along with a power source and a PCB to connect everything.

  • 2
    Bill of Materials (Sans Lens)

    LCD: $17.56

  • 3

    I’ve included the necessary files to manufacture a pocket projector, including the schematic, PCB, and necessary libraries on this project’s GitHub page, as well as in the "Files" section of this project.

View all 3 instructions

Enjoy this project?



Similar Projects

Does this project spark your interest?

Become a member to follow this project and never miss any updates