This like many other pages are a Work In Progress.

This electronic sensor system is best used with a computer tracking software such as Grand Prix Race Manager (GPRM) by Randy Lisano. My research found this to be the best software for the job and one of the best prices. It makes races run faster and more organized, this makes it more fun.

These plans incorperate the Micro Wizard electronics and my own design for the sensor bridge and componant location.

I have previously built them into the base of the track itself or in a project box, many people build them into the finish line over the track like this one. I have modified the manufactureres ideas a little moving some of the connectors to an interface box. The nice thing about this design of the circuit is it allows you to keep the interface box near the computer. Meaning the only long cable you might need is a very easy to find and relatively inexpensive one, a Cat 5 cable. It is peanuts compared to a long serial cable and the start switch wire only has to be run 3-5 feet instead of all the way down the track to the finsh line.

Another nice thing is the adapter box sits right behind my computer so the serial to USB adapter goes from the box the the computer.

Click on these images to link to a larger version. Just use your browsers Back button to return.

If you wish a Solenoid Start Gate, I have made a schematic for it. Click here.

Constructing the Lane Sensor Bridge

IR LED Mounting- You need to build a frame to suspend the IR LED's over the track lanes.
I prefer the aluminum bridge for it's low profile and strength and ease of use, but it can be made of wood.

Aluminium Bridge: Use 3/4 inch Channel Top and Bottom and 3/4 inch SquareTube for the uprights.
These pieces can be found at you local Home Depot or Lowe's etc. You will need LED mounts for this option and your holes will have to be the right size for the mounts you choose. you can also glue them in place with silicone or hot glue. Sections of aluminium are bolted together using 8-32 machine screws and nuts.

Measure the width of your track and where to centers of the lanes are. Cut three pieces of channel to the width of the track plus 1 1/2" for connection to the uprights. Deside what hieght above the track you want the bridge then add the thickness of your track as the bottom of the bridge runs under the lane surface and a little extra room in addition to the 3" you need for the electronics and cut the uprights. Most organizations have a max hieght of 3" for their cars so 8" uprights should do nicely.

Cut the ends of the lower and middle channel to allow the uprights to fit into the sides. Drill holes for the bolts. Also drill holes for the wires in one upright allowing for plenty of room.

Make sure to stack the aluminium channel used for the IR LED's and the Photo transistors together and then drill the holes through both pieces at once. This way the holes will line up properly, but care should be taken to drill the holes perpendicular to the material. Use a drill press or a drill with a built-in level.
Insert the LED's into the mounts (if you are using them) and snap into place in the channel. Use silicone or hot glue to secure them in place if disired.

Next attach the wires to the IR LED's leads and use heat-shrink tube or tape to cover the connections to prevent shorting. You can mount the photo transistors just as you did the IR LED's. Insert the photo transistors, attach the wires to the leads and add heat-shrink tube or electrical tape.

Now with the track, drill holes in each lane at the finish line, a bit larger than the holes in the "bridge" and then depending on your track design, attach guides to hold the sensor bridge in place or cut holes for the sensor bridge to slide through under the track.

Housing the Circuit Board

Connect the wires to their corresponding locations on the circuit board. Also, if using display LEDs, drill holes for those and secure in place.

Start Sensor

Almost any switch will do. Originally I used a commercial momentary push button (found at any electrical supply, and some Home Depot's) mounted on a small 2 inch angle. I felt that because I was having the start gate land on the switch a small cheap switch just wouldn't do. Also it is only 5VDC so I did not enclose it.

I prefer a magnetic switch similar to one found in an alarm system, but has N.C. contacts that open when the magnet is brought close to it. Screw or use two sided tape to secure the switch in place with the magnet on the drop gate. Attach a wire to the switch with a standard 1/8" phone plug on the other end (or what ever connector you use) to plug into the system.

Any questions I might be able to answer, feel free to send a message to Dave

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