Stoplight controller details

It’s been a long time since I promised myself that I would post details of the stoplight controller. The controller is based on the Arduino Duemilanove, with a custom shield containing relays and connectors for the sensors.

The lights in the stop light itself are turned on and off by six 3A, 120V relays on the shield. The shield also has an independently controlled set of six LEDs and a few miniature buttons, mirroring the function of the main lights, switches, and sensors. The controller is housed in an 8″ plastic electrical box with a lexan cover. I have a bit of work to do yet to tidy up the wiring and strap down the transformer inside the box, but the  I cut a large hole in the side to hold the connectors for the sensors and button box, which use color-coded cat‑5 ethernet cables.

The distance sensors are Maxbotix LV-EZ1, which put out an analog signal that the shield passes along to the Arduino. The distance sensors fit perfectly inside these surface mount ethernet boxes with a 1/2″ hole drilled in them. Adding keystone jacks to the boxes makes connecting cheap cat‑5 cables simple and tidy. The sensors are mounted in front of each parking space. The Arduino runs a simple serial port interface program that can be used to program the controller with the threshold distances that change the light colors. The threshold distances are saved to the Arduino’s internal nonvolatile memory. The Arduino is positioned in the box such that the USB port is accessible from the outside, making updates and reprogramming simple.

The garage door open sensor is a C&K Components MPS80WGW magnetic switch. When the garage door opens, the magnet attached to the door moves away from the switch mounted by the door track, telling the controller that the garage door has opened. The controller then goes into parking mode, and changes the lights from green to yellow to red as the car pulls in.

A separate button box houses a couple great clicky arcade buttons that can make the controller perform some different light shows. The box is a simple 4″ grey plastic electrical box from the hardware store with a couple holes drilled in it, making it very durable.

2 Responses to “Stoplight controller details”

  1. Jeremy says:

    Hey, Im sonictraxx on youtube.

    I think your creation is really cool!
    How long did it take you to make this?

    And I am serious about what I said before; would you consider building me an identical setup to yours? I have two 8″ signals already. I just don’t have enough know-how about arduino to know what im doing.

    How much would you charge?

  2. Ryan PItts says:

    Hey Christopher,

    I have a stoplight that i bought at an antique store and i was actually trying to do the exact thing with it as you have done. I’m technically minded, but more computer programming and i haven’t done much with circuits before.

    Would you be willing to build a replica of your system (without the light obviously) for me? Of course, i would pay you for the materials and compensation for your time as well. Heck, i’d even pay you before you built it if needed. What do you think?? Please at least let me know if it’s a no.

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