Information for V1 timer boards

Here is a picture of the bare board and a completed board for reference.

In order to complete the project you will need to add the following components:

• Right angle, PC board mount DB-25 male connector (unless you buy the kit that includes the connector)
• Five 10K-Ohm resistors (Radio Shack #271-1335, $0.99 for a 5 pack)
• Start switch
• Lane sensors (see parts list above or discussions on the forum for suggestions)
• Hookup wire for start switch and lane sensors
• +5 volt power supply

You may not need the resistors OR the 5 volt power supply if your computer has built-in pull-up resistors. Unfortunately there is no real way to know if your computer has the built-in resistors. Some do, some don't. If your computer does not have pull-up resistors your timer may operate erratically or it may give sluggish results.

Assembly Instructions

Refer to the completed board photo as necessary:

• Make sure you insert all components on the BLANK side of the board. The side with the traces is only used to solder parts in place. There should be no components on the solder side (the side with the traces).
• Insert the pins of the DB-25 connector through the holes and solder the pins in place. It is not necessary to solder every pin. You can simply solder all the pins with traces to them, plus a few on the opposite end of the connector to help hold it in place.  In order to keep the board cost low I elected not to put a solder mask on the board. Make sure that you don't accidentally solder bridge between two pins or between a pin and a trace. This is especially easy to do near pin 2, pin 9, and pin 13.
• Next insert the resistors into the holes in the middle of the board. Resistors are not polarized so it doesn't matter which end goes which way. Flip the board over and solder each resistor in place. Again, make sure that you do not solder bridge between a pin and an ajoining trace.  Clip off any excess resistor leads that are sticking out of the back of the board.
• Solder wires onto the ends of the phototransistors for each lane. Use one color of wire for the emitter and a different color for the collector on each sensor. This will make the next step MUCH easier and less error prone. Use just enough wire to reach from the back of your PC to the track. I would use no more than 3 to 5 feet of wire on each phototransistor. Each sensor should have the same amount of wire as all the others for proper timing (electricity travels about 9 inches per nanosecond so if one wire is 9 inches shorter than another, the timing will be off by 1 nanosecond between the two sensors). Also solder (or otherwise attach) a wire to each side of the start gate switch. Remember to leave enough wire to stretch all the way to the top of the track.
• Refering to the solder side of the board, note that there are 5 rows of two holes each on the right side of the board. These are the connections for the start gate (at the top, notice the word "start" above the top row of holes) and the lane sensors (rows 2-5 = lanes 1-4 respectively). On the right side of the rows is the word "emitter" which indicates where the emitter from each sensor should be connected (the wire from the collector goes in the other hole in each row). Flip the board back over so you are looking at the component (blank) side and then run the wires through the board and solder them in place making sure to connect the emitter to the correct side on each row. Alternately, you can solder a connector in place (as in the photo) and then connect the wires to that so that you can attach and remove the sensors easily. While you are at it, solder the wire from the start gate to the top row of holes (polarity does not matter for the start gate, either wire in either hole will work).
• Now hook up a regulated 5 volt power supply to the board. Again refering to the solder side, note the markings for "+5" and "GND" which indicate where the +5 line and the ground line from the power supply should be connected. Note that the power supply is not hooked up in the photo.
• Now, DOUBLE CHECK EVERYTHING!!! I refuse to be held responsible for damage to your computer if you have not connected things correctly and double checked your work. Make sure you have the +5 and ground from the power supply connected correctly. Plug in the power supply and check the voltages with a meter to confirm this. While you are at it, check that the various pins on the DB-25 change state properly when you cover and uncover the phototransistors. You should be able to check this quite easily using a volt meter.
• ONLY after you have checked EVERYTHING and then DOUBLE CHECKED everything should you attach the circuit to your PC. Run the pinewood software and use the diagnostics screen to confirm that each of the bits changes state properly when you cover and uncover each phototransistor. Also check that the start gate switch changes states correctly. If not, carefuly review the instructions above to make sure you haven't missed anything. Check closely for phototransistors that are not hooked up correctly (emitter and collector reversed).