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Page 2 – Design

Page 2 – Design


IR LED Emitters - wiring options

IR LED Emitters – wiring options

To find the best way wire up the IR Emitters, I used the LED Wizard located here and fed in the specs of the LEDs and the count. It gave me a couple of solutions and I decided to go with the second. I am powering them from +5v and they will be paired with a current limiting resistor (27 ohm 1/2 watt). On the breadboard this works great and the parts do not heat up even after running for a few minutes. NOTE: make sure you use the correct wattage resistors otherwise they will become quite hot.


Process Diagrams and Schematics

These diagrams and schematics are what I used to document the design for the timer. I did some samples / POCs to figure out what I think would work. That way I could follow this as closely as possible when writing the code and building. However once I built the timer and wrote the code I realized I did not really need some functions (like the status check function) or the start gate servo so these will not exactly reflect the device and code that I used on our track. With that said everything here should allow you to design your own timer but if you get stuck please let me know.

Note: I did not create a wiring diagram explicitly for the finish line that shows the connections from the RJ-45 to the various parts at the finish line, but the Breadboard view of the timer shows how they are connected. between that and the Device side wiring Diagram for the RJ-45 you can figure out which pin of each plug will be a lane or the start gate.  the design calls for standard Ethernet cables (not crossover!!!) to connect the device to the finish line and the finish line to the start gate.

Build and Construction notes

Here is the link to the CodePlex project with the source code for the timer:

These are the previous posts covering construction, operation of track, testing, along with pictures:

Page 3 – Setup

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One response to “Page 2 – Design

  1. Pingback: Track Timer – Additional Build Details and Source code « Fun with Electronics and Code

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