HO Slot Car Racing - Lap Counters & Lap timer 2000 Printer & Joystick Interfaces Lap CountersOnce you have built your HO scale slot car track you will want to think about adding a lap counter and timer. Most lap counter software requires a personal computer running either MS DOS or the Microsoft Windows operating system. These software programs normally count and time laps using an interface cable connected to either the printer port or the joystick interface.Note: The information provided here can also be applied to 1:32 and 1:24 scale slot car tracks as well as HO layouts.See the section of this web site for detailed photographs of how a lap counter and timer can easily be installed in your layout.Computer InterfacesThe diagrams below illustrate the various port interfaces possible using an MS DOS or Microsoft Windows based computer system. Wiring diagrams are shown for the Game Pad Interface, The Parallel Port and the I/O Port.Joystick InterfaceThe diagram below illustrates a typical slot car lap counter interface using the joystick game port found on most personal computers. The longer lead on the photo-cell (Emitter) is connected to the common signal ground (pin 4).The numbered connections running down the left edge of the wiring diagram correspond to the numbered pins on the Joystick Game Port connector.
Slot Car Tracks For Sale: Forum for advertising slot car track for sale, of any scale. A good rule of thumb is to include a power tap every 10 - 12 track sections. Power taps will generally be made using straight sections of your track (though it is possible to use a curved piece of track if absolutely necessary). Some other considerations when locating and installing power taps are listed below.
The four sensors numbered Lane 1 - 4 correspond to the switches or photo-cells needed for each lane on your slot car track.The 100K Ohm resistors aren't used by the lap counter itself, but must be included to represent the X- and Y-Axis potentiometers found in a joystick device. Without them MS Windows can not detect a joystick device connected to the game pad port.Warning: Run two separate wires from each sensor at the track all of the way back to the connector at the computer.
Do not tie the ground lines (pin 4) together under the track.If your PC has a multi-media sound card installed check the connectors at the rear of this card, most sound cards have an integral 15-pin joystick game port built in. The standard joystick game port can handle up to four 'fire' buttons, that is enough for a simple four lane lap counter.
If your computer does not have a joystick game card installed you can purchase one for as little as $25.00 dollars.You will also need to configure MS Windows to recognize the joystick interface cable you've built. Follow the instructions described in the section to define a suitable device.Printer InterfaceThe diagrams below illustrate typical slot car lap counter interfaces using the Parallel Printer Port found on most personal computers.
The longer lead on the photo-cell (Emitter) is connected to the common signal ground (pin 25).The wiring diagrams above illustrate typical 4-lane lap counter interfaces. The numbered connections running down the left edge of the wiring diagram correspond to the numbered pins on the Parallel Printer Port connector. The four sensors numbered Lane 1 - 4 correspond to the switches or photo-cells needed for each lane of your slot car track.Warning: Run two separate wires from each sensor at the track all of the way back to the connector at the computer. Do not tie the ground lines (pin 25) together under the track.Note: Pins 18 - 25 on the standard LPT port are all grounded, so you could just as easily used separate ground pins for each of the four sensor lines.Serial I/O InterfaceThe diagram below illustrates a typical slot car lap counter interface using the Serial I/O Port found on most personal computers. Both DB-25 and DB-9 connectors are shown below. Most lap top computers use the smaller DB-9 connector, while full-sized desktop system usually have DB-25 connectors.The wiring diagram above illustrates a typical 4-lane lap counter interface. The numbered connections running down the left edge of the wiring diagram correspond to the numbered pins on the Serial I/O Port connector.
The longer lead on the photo-cell (Emitter) is connected to the common signal ground (pin 7 or 5).Warning: Run two separate wires from each sensor at the track all of the way back to the connector at the computer. Do not tie the ground lines (pin 5/7) together under the track.Track Switches & SensorsSeveral different methods are available for detecting when a slot car passes over the start/finish line of your slot car track. These approaches break down into two basic categories; electro-mechanical and optical. Of the two, optical detection is the better choice.Dead TracksThe Dead Track method requires a specially made section of straight track as illustrated below.Two 5/8' sections of each rail must be removed to create a short dead rail approximately 3' in length.
The two red wires in the diagram above are connected to the joystick game port interface card to create a 'switch'. When a slot car passes over this section of track the pickup brushes and motor 'close' the switch.Because you have cut the lane rails to create a dead section you will need to also tie the power rails back together with short jumper wires. The blue wires in the diagram above allow power to flow around the dead section.There will be a momentary loss of power to a slot car as it passes over this dead section of track.
To avoid stalls you should place your dead track section along a fast straight.Tip: The easiest way to create a dead track section is to use a 6' section of straight track with 5/8' sections removed from the rails at both ends of this piece of track. Position this dead track section between two straight tracks wired as power terminal sections. See the section of this web site for further instructions on making power terminal tracks and dead sections.Warning: Dead Track sections can be harmful to the printer and serial ports. DC motors act like DC generators when they spin freely, so dangerous voltages (Back-EMF) can be induced into the signal lines as cars coast over the dead section.Note: The Joystick interface has isolated inputs that protect the port from these dangerous and potentially damaging DC pulses, but printer and serial ports do NOT.Photo-CellsThe Photo-Cell Switch method requires a small 1/8' hole to be drilled between the guide pin slot and one of the power rails.
The photo-cell is mounted under the track facing up through the hole you drilled. The photo-cell leads are then connected directly to the joystick game port interface board.See the section of this web site for detailed photographs of how the photo-cells can be mounted under the track.I sell 2- and 4-Lane Photo-Cell Cables with your choice of Joystick or Printer port interfaces in the section at the end of this page.Photo-cells are sensitive to the infra-red (heat) portion of the light spectrum. Any small incandescent lamp will produce enough heat energy to work properly.Fluorescent light however does not contain enough infra-red energy to work reliably.If you plan to use IR-LED devices as emitters keep in mind when wiring and testing that they produce no visible light, but will produce infra-red energy suitable for use with photo-cell detectors.A light source must be placed directly above the section of track containing the photo-cell switches. Each time a car passes over the photo-transistor the light beam will be broken causing the switch to close.Magnetic Reed SwitchesThe Magnetic Reed Switch method requires small magnetic reed switches to be placed under each lane. As a slot car passes over this section of track the slot car's motor or traction magnets momentarily closes the reed switch.Reed Switches suitable for lap counters are available in the section at the end of this page.Orientation of the reeds inside the switch itself is very important. Make sure you install the reed switches so that the two moving blades are positioned next to one another like the diagram below.When a slot car passes over the reed switch the two blades should move from side to side, not up and down.