Stranger Things Alphabet LED Wall - Matrix Multiplexing (With Wireless Control)

Authors: Shota Bzikadze, Giorgi Mchedlishvili

Difficulty: Easy-Intermediate

Estimated Time: Weekend Project (or a few afternoons)

Prerequisites: Basic breadboard and circuit wiring knowledge, basic crafting tools.

Cost: Under $30–$50 (Depending on what you already have in your workshop)

Bring the Upside Down to life with your own Stranger Things alphabet LED wall, built entirely from affordable, off-the-shelf components!

Created as part of a competition hosted by Spark Community (Georgian makers and engineers community), this project proves that you don't need expensive gear to build an eye-catching interactive display. The core idea is refreshingly simple: the design is fully scalable, making it easy to adapt for small personal projects all the way up to industry-level installations.

Everything is constructed using accessible components that are widely available worldwide, keeping costs low and sourcing hassle-free. By prototyping the circuit on a breadboard and utilizing minimal active switching components like relays and shift registers, the setup stays clean, efficient, and straightforward to assemble.

Whether you're looking to recreate the iconic communication wall from the show or exploring scalable lighting control for a custom build, this guide will walk you through the entire process step-by-step!

Note: The picture does NOT contain all of the parts needed for the project.

Microcontrollers And Components:

Arduino NANO - x2

5V Relay Module - x12

74HC595 Shift Register - x2

NRF 24L01 - x2

TFT Screen - x1

LED - x26

DC-DC Step Down converter - x3

Materials And Wiring:

Wooden Board (approx. 1.5m x 1.5m)

Breadboard (for prototyping)

Jumper Wires, Buttons, & Switches

Wire (suitable gauge for powering the LED array)

Power Supply – (18650 batteries, a power drill battery pack, 9V batteries, etc.)

Tools Required:

Common workshop hand tools (drill, measuring tape, cutting pliers, wire strippers, utility knife)

Soldering iron & solder

Multimeter

Electrical tape (isolation tape) / Heat shrink tubing

One of the best things about this project is its accessibility—you likely already have many of these components lying around your workbench, garage, or spare parts bin. If not, every part listed here is cheap and readily available at almost any local electronics shop, hobby store, or online marketplace worldwide.

When building a Stranger Things alphabet wall, you have 26 individual letters. If you used a traditional wiring setup, you would need 26 separate relays or output channels—one for every single letter.

Instead, we use a Matrix Configuration to control all 26 letters using a fraction of the hardware.

The Math: Maximizing Your Relays

By arranging your wiring into Rows (Positive) and Columns (Negative), you can drastically multiply your output using very few relays.

If you divide your available relays evenly between rows and columns, you multiply them rather than add them.

Example: With 12 relays, you can set up 6 rows and 6 columns (6 x 6). This gives you an absolute maximum of 36 individual intersection points, which is more than enough to cover all 26 letters of the alphabet!

The minimum relays needed for this project would be 11 [5 x 6]. 10 Relays won't work because 5 x 5 = 25, which is less than the 26 outputs.

How It Works (One LED at a Time)

Unlike high-speed digital multiplexing that relies on rapid visual persistence, this relay-based setup lights up one letter at a time:

The Positive Line: A single positive line (controlled by a row relay) feeds power into the chosen row.

The Negative Line: A single negative line (controlled by a column relay) opens up the return path for the chosen column.

The Intersection: Current flows only through the single LED sitting precisely at the intersection of that active row and active column, lighting up that specific letter on the wall.

By sequencing which row and column relays are activated, you can spell out words letter by letter using a clean, minimal hardware footprint!

Now it’s time to bring the physical wall to life by building the wooden board, laying out the letters, and prepping your individual LEDs.

Layout, Painting and Drilling

First, take your wooden board and plan out your layout. As shown in the design reference, the alphabet is split into three horizontal rows following an 8-9-9 letter configuration:

Row 1 (A–H): 8 letters, with roughly 17 cm spacing between them.

Row 2 (I–Q): 9 letters, with roughly 15.5 cm spacing between them.

Row 3 (R–Z): 9 letters, with roughly 15.5 cm spacing between them.

Paint or stencil your classic Stranger Things style letters onto the board. Once the paint is dry, carefully drill holes directly above or integrated with each letter where your LEDs will push through from the back.

Harvesting and Testing the LEDs

Instead of buying individual loose LEDs, this project uses standard string lights (like Christmas lights or similar LED strings) cut down piece by piece.

1. Cut them out: Snip individual LEDs from the string, leaving enough wire leads attached to solder onto later.
2. Find the Polarity: Because cut string lights don't always have obvious color coding, you need to find their positive and negative legs. Set your multimeter to diode mode and touch the probes to the leads until the LED lights up.
3. Important Warning: Do not leave the multimeter probes connected to the LED for too long! The current supplied during diode testing can easily burn out or degrade the LED if held continuously. Test quickly, note which side is positive and negative, and move on.

Matrix Wiring on the Back

With your LEDs secured in the board, it's time to wire them up according to our matrix logic:

1. The Rows (Positive): Connect the positive legs of all LEDs belonging to the same horizontal row together into a shared positive line (Row+).
2. The Columns (Negative): Keep the negative paths separated so that every individual LED has its own distinct negative return path, completing the matrix grid on the reverse side of your board.

With the components gathered, it is time to wire everything together. The circuit brings together a microcontroller, wireless communication, shift registers for pin expansion, and a relay matrix to control the individual letters.

Take a look at the wiring diagram above, and follow the breakdown below to connect each section properly.

Power Supply And Regulation

Power Source: Connects into the dual regulator/buck converter modules at the top left.

5V & GND: One regulator steps down/stabilizes power to supply clean 5V and GND for the logic components (Arduino, shift registers, and nRF module).

LED Power: The secondary lines provide dedicated LED+ and LED- rails to handle the higher current required for the string lights.

Microcontroller And Wireless Control (Arduino Nano & nRF Module)

Arduino Nano: Acts as the brain of the project, processing incoming wireless signals and sequencing the light patterns.

nRF Module: Connected to the Arduino using standard SPI communication lines and powered by the 3.3V pin. This allows you to control the wall wirelessly (e.g., via remote or automation).

Pin Expansion (Dual 74HC595 Shift Registers)

Because a standard Arduino doesn't have enough direct pins to control a full matrix of relays independently, two 74HC595 shift registers are daisy-chained together. 1st Register's pin 9 goes into 2nd register's pin 14. They take a few data, clock, and latch lines from the Arduino and expand them into enough parallel outputs to drive the entire relay board.

Pin Connections:

1. 74HC595 Shift Registers:
2. DATA (DS/SER): Pin 6
3. CLOCK (SH_CP/SRCLK): Pin 3
4. LATCH (ST_CP/RCK): Pin 2
5. nRF24 Wireless Receiver:
6. CE: Pin 4 | CSN: Pin 5
7. SCK: Pin13 | MOSI: Pin11 | MISO: Pin12

Matrix Wiring Layout

The system controls letters by activating one Positive Row relay and one Negative Column relay at the same time:

1. Row 1 (A – H): Row 1 Relay + Columns 8 through 1 (A = Col 8, H = Col 1)
2. Row 2 (J – Q): Row 2 Relay + Columns 8 through 1 (J = Col 8, Q = Col 1)
3. Row 3 (S – Z): Row 3 Relay + Columns 8 through 1 (S = Col 8, Z = Col 1)
4. Row 4 (I & R): Row 4 Relay + Column 7 (I) or Column 8 (R)

Note: The column connections are horizontally mirrored (cba order) to match the physical layout of the wall wiring.

Pro-Tip: Double-check your ground connections across all modules! Keeping a common ground between your power regulators, Arduino, and relay boards prevents erratic signal behavior and ensures stable switching.

The transmitter acts as the control hub, allowing you to select and send words or patterns wirelessly to the LED wall. It features an Arduino Nano, a 1.44-inch TFT LCD display for menu navigation, an nRF24 radio module, and a 5-button directional keypad.

Power Management: Why a Dedicated 3.3V Buck Converter?

An external 3.3V buck converter is used to step down the main power alongside a 5V converter. The Arduino Nano's built-in 3.3V regulator cannot provide enough current to safely power both the power-hungry nRF radio module and the TFT display simultaneously, which can cause voltage drops, reboots, or wireless dropouts. Using a dedicated external buck converter ensures stable, clean power for all 3.3V logic components.

Component Connections

1. Power Rails:
2. 5V Rail: Powers the Arduino Nano.
3. 3.3V Rail: Powered by the secondary buck converter to supply the TFT display and nRF24 module.
4. TFT LCD Display: Connected to the 3.3V power rail, ground, and control lines (SCL, SDA, RES, DC, CS, BL) for rendering the user interface.
5. nRF24 Radio Module: Connected to the 3.3V power rail, ground, and standard SPI lines (SCK, MOSI, MISO) plus custom control pins (CE on D4, CSN on D5).

Control Buttons Pinout

The physical directional pad and selection button are mapped to the following Arduino Nano pins:

1. RIGHT: Pin 2
2. DOWN: Pin 3
3. LEFT: Pin A0
4. UP: Pin A1
5. OK: Pin A2

Now that all the hardware is wired up, it's time to bring the system to life by flashing the code to both your receiver (the LED wall) and your transmitter (the controller). [View Code Files Below]

Required Libraries

Open your Arduino IDE and install the following libraries via the Library Manager (Tools > Manage Libraries...):

1. RF24 (by TMRh20) – Handles the wireless communication between the controller and the wall.
2. Adafruit GFX Library (by Adafruit) – Used to render the UI on the transmitter’s TFT display.

Pro-Tip: A Quick Word on nRF24 Troubleshooting

1. Match Your Channels: Learn from our 2 days of debugging headaches—ensure both your receiver and transmitter code are set to the exact same channel!
2. Avoiding Interference: Default channels (like channel 76) often suffer from heavy interference from local Wi-Fi and Bluetooth devices, which can block your nRF modules from connecting. If you experience connection drops, try shifting both devices to a less congested channel (such as channel 10) and ensure your power supply is clean and stable.

Congratulation! You have successfully built a working alphabet LED wall from Stranger Things