AvBrand Exploring Technology
AvBrand Exploring Technology
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The LED Sign

One of the things I've always wanted to have in a car is a programmable LED sign facing the rear, to send messages to the drivers behind. I've always had an interest in LED signs and recently added one to my home. So I finally got one for my car put together and working!

Before you implement a sign like this in your car, it's important to check the local traffic regulations. In Ontario, the Highway Traffic Act governs everything to do with lighting: What kind, what colour, which direction, flashing or non, etc. Many stores sell cheap red LED signs, but not only are these nearly impossible to see in daylight, they are also illegal. Same goes for those license plate frame message signs.

So, what I ended up buying is a "semi-outdoor" or "window" Amber LED sign. Amber is allowed, unlike red. Semi-outdoor/window means the sign has high-brightness LEDs, unlike indoor signs, so the message can be easily viewed in direct sunlight.

I reverse-engineered the serial data protocol that the sign uses, and with the help of Grinthock, we installed it into the rear of my car. I ordered a 3 amp 12V to 5V regulator from mp3car.com to power the sign.

Update: The New LED Sign

In May 2012, I was contacted by a representative of brightledsigns.com, asking if I'd be interested in replacing my Amber-colored NS500 LED window sign with the 3-color model of the same sign. Full disclosure: They offered to send me one in exchange for me checking it out and putting it up on my site.


The sign has one high-brightness red and one high-brightness green LED for each pixel. This means it can still create Amber by turning both LEDs on, but be warned, the color is more of a yellowish-green, vs the true amber that the previous sign created. However, I will still interested in trying it out. I figure I can use Amber most places and then green or red in special occaisions, even if they may be skirting the Highway Traffic Act.

Here's a quick video:

The green text looks incredibly sharp and easy to read, and I think it's a huge improvement over the old sign. Since it uses the same 5V power supply, mounting brackets, and serial cable, it was a drop-in replacement. However, the serial protocol is completely different and required me to, once again, reverse engineer the protocol. The new sign runs at 4 times the speed of the old one, and has a much simpler protocol, so it is much easier to use and can be programmed much much faster.



This page in my Car PC software controls the sign:

There's lots of space left as I expand the available messages. There's also a CUSTOM button where you can type your own message:

Technical Details - New Sign

I've had a lot of requests for more technical details about the LED sign. Please proceed to the new New LED Sign Technical Details page, where you will find the sign's model number and protocol documentation.

You can buy this exact sign here: 4x26 Windowfront Three Color Programmable LED sign for $219.

The Old LED Sign

Technical Details - Old Sign

I've had a lot of requests for more technical details about the LED sign. Please proceed to the old Old LED Sign Technical Details page, where you will find the sign's model number and protocol documentation.

Move on to Part 5 - Voice Recognition

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