Rear Window LED Marquee


Robert Dunn soldered 480 red LEDs into a grid in the rear window of his truck:

The LED Sign itself is a 48×10 soldered together matrix of red LED’s. I soldered them together sparsely in a mesh so it could be mounted in the back window without losing rear visibility. The rows are controlled using a 4017 decade counter for POV. The columns are controlled using six 959 shift registers.

Input from the vehicle is recieved from the trailer light hookup through a cable and into the cab. The signal from the trailer lights hookup is connected to the arduino using optocouplers. The arduino can sense both turn signals and the lights using this setup. The 12v signal is regulated down to 5v for the optocoupler using 7805 voltage regulators. There was probably somewhere in the cab to get the turning signal input from, but it was easier to use the trailer hookup, although uglier.

Via Hackaday

Adafruit publishes a wide range of writing and video content, including interviews and reporting on the maker market and the wider technology world. Our standards page is intended as a guide to best practices that Adafruit uses, as well as an outline of the ethical standards Adafruit aspires to. While Adafruit is not an independent journalistic institution, Adafruit strives to be a fair, informative, and positive voice within the community – check it out here:

Join Adafruit on Mastodon

Adafruit is on Mastodon, join in!

Stop breadboarding and soldering – start making immediately! Adafruit’s Circuit Playground is jam-packed with LEDs, sensors, buttons, alligator clip pads and more. Build projects with Circuit Playground in a few minutes with the drag-and-drop MakeCode programming site, learn computer science using the CS Discoveries class on, jump into CircuitPython to learn Python and hardware together, TinyGO, or even use the Arduino IDE. Circuit Playground Express is the newest and best Circuit Playground board, with support for CircuitPython, MakeCode, and Arduino. It has a powerful processor, 10 NeoPixels, mini speaker, InfraRed receive and transmit, two buttons, a switch, 14 alligator clip pads, and lots of sensors: capacitive touch, IR proximity, temperature, light, motion and sound. A whole wide world of electronics and coding is waiting for you, and it fits in the palm of your hand.

Have an amazing project to share? The Electronics Show and Tell is every Wednesday at 7pm ET! To join, head over to YouTube and check out the show’s live chat – we’ll post the link there.

Join us every Wednesday night at 8pm ET for Ask an Engineer!

Join over 36,000+ makers on Adafruit’s Discord channels and be part of the community!

CircuitPython – The easiest way to program microcontrollers –

Maker Business — “Packaging” chips in the US

Wearables — Enclosures help fight body humidity in costumes

Electronics — Transformers: More than meets the eye!

Python for Microcontrollers — Python on Microcontrollers Newsletter: Silicon Labs introduces CircuitPython support, and more! #CircuitPython #Python #micropython @ThePSF @Raspberry_Pi

Adafruit IoT Monthly — Guardian Robot, Weather-wise Umbrella Stand, and more!

Microsoft MakeCode — MakeCode Thank You!

EYE on NPI — Maxim’s Himalaya uSLIC Step-Down Power Module #EyeOnNPI @maximintegrated @digikey

New Products – Adafruit Industries – Makers, hackers, artists, designers and engineers! — #NewProds 7/19/23 Feat. Adafruit Matrix Portal S3 CircuitPython Powered Internet Display!

Get the only spam-free daily newsletter about wearables, running a "maker business", electronic tips and more! Subscribe at !


  1. He could make some side money by having it scroll messages across the back. “Eat at Joe’s”

  2. I’ve wanted to make that for a long time. Except mine would say KEEP RIGHT EXCEPT TO PASS for every time some jackass makes me pass them on the right.

  3. Since he’s got it connected as directionals/hazzards it’s legal. Anything else involving red lights other than directional or break lights is illegal in the US, so scrolling marquee signs are a good way to get yourself a ticket.

  4. cool way of using LED and that is what semiconductor technology has gave as LED and even the manufacturing of led are in boom that I am wondering the application of led is getting so vast that it is been used everywhere like in marketing with led signs or in lighting purpose or in decoration.

Sorry, the comment form is closed at this time.