Creating a Ghost Car for Carrera DIGITAL 143 Racing

By Michael Ashton

I really enjoy racing on the Carrera Digital 143 track when I am fortunate enough to have someone to race with. Unfortunately there are no other slot racing enthusiasts located within hundreds of miles of my home, so I only have a few months out of the year that I can actually race with other people when a couple of friends come to my area for the winter. The rest of the time is spent tinkering and running cars alone.

A nice feature of Carrera’s Digital 132 system that would really be great for a “lone wolf” racer like myself is the autonomous or ghost car. This is where a digital car can be programmed to run around the track at a constant speed while changing lanes in a random fashion. I like to call it a nuisance car because its purpose is to make the racing more interesting and exciting by causing traffic jams, getting in the way of the human-operated cars and acting like, well… a nuisance. So, if there is no one else to race with, you can race against (or around?) the nuisance car.

It's too bad that this feature is not available in the D143 system. Nevertheless, there is a way to simulate the ghost car function on a D143 track. And it requires absolutely no modification of any system component and virtually no additional expense. We’ll name it the D143 Ghost Car and note that the lane changing capability is made possible by a design characteristic of the D143 lane change track. So first, a little background on the operation of the lane changer:

The first photo below shows the lane changing mechanism or, flipper, depicted by the yellow arrow. The flipper is in its closed or, “no change” position. Cars passing over the receptor, shown by the white arrow, with the speed controller’s lane change button not depressed, will continue in the current lane.

The next photo shows the flipper in its open or, “change” position. The flipper shifts to this state when a car passes over the receptor with the speed controller’s lane change button depressed. The car will be diverted into the crossing slot and change to the opposite lane.

A very interesting characteristic of the operation of this mechanism, which I think is unique to the D143 system, is that the flipper is not spring loaded (i.e., it does not spring back to the closed state). Instead it remains in the change state until a car passes over the receptor with the speed controller’s lane change button not depressed, at which point the flipper returns to the no change state, allowing the car to remain in the current lane. However, if the next car passes the receptor with the speed controller’s lane change button depressed, the flipper remains in the change state and the car changes lanes. It is this characteristic that allows a pseudo random lane changing function to be implemented.

The Setup

The emitter that triggers a lane change is located on the underside of the D143 car’s chassis. All that is required is to cover this emitter so that it cannot be detected by the receptor in the lane change track and the car will not change the state of the flipper. It is now, in effect, a D143 ghost car. This means that if the preceding car has set the flipper to change, the D143 ghost car will also change. If the preceding car has set the flipper to no change, the D143 car will continue in the current lane. In effect, it will obey the current state of the flipper, regardless of any action of the speed controller’s lane change button. Although the lane changing action is not truly random, it will be difficult at best to predict the action of the D143 ghost car while concentrating on the human-driven car.

In the following photo, a circular red sticker has been placed over the car’s emitter opening, indicated by the yellow arrow. The emitter is recessed into the chassis enough so that adhesive from the sticker should not contact the surface of the emitter as long as the sticker is not pushed into the opening. Masking tape could also be used for this purpose. Note that this will also prevent the car from registering laps on the D143 Lap Counter.

Now that we have lane changing, we can turn our attention to the other aspect of the ghost car — speed control. As with lane changing, the method used to implement speed control is low-tech, virtually cost-free but surprisingly effective. Yes, the following photo shows an external continuously adjustable variable throttle pressure device. Also known as a rubber band (see the red arrow). OK, I can hear the sniggering in the background, but this method works very well. There is just enough friction in the throttle plunger to enable the speed adjustment to hold reliably — even as fine adjustments are made. The yellow arrow points to the GO!!!/D143 throttle governor which also helps maintain the throttle position while limiting maximum speed to something that is manageable. Of course you will need to experiment with different sizes and thicknesses of rubber band in order to achieve just the right downward pressure on the plunger.

Now, just place the D143 ghost car in either slot, turn on the power and it will start immediately. Once you find the correct length and thickness of rubber band you should be able to fine tune the throttle position to achieve a speed that suits your specific need. I find setting the speed so that the ghost car can handle every curve while also not hesitating on the lane changers’ dead spots works best for me.

Next, place a human-controlled D143 car in the slot and just start running. As you run and start to change lanes the ghost car will follow the state of the lane change flippers. It won’t be long before the interaction between the two cars will start to reveal situations that will make the running more interesting. For example: eventually the human-controlled car will end up behind the ghost car and a lane change will be required in order to pass; or the human-controlled car can change lanes while just behind the ghost car and then try to time each subsequent lane change so that the cars are always crossing paths and never in the same lane; or just see how many times the human-controlled car can lap the ghost car. There are likely many different scenarios to be discovered and I’m still experimenting.

Perfect? No. Effective? Yes. Fun? Absolutely!

Some things to consider about this method of implementing a ghost car capability:

• There are some drawbacks. The primary disadvantage being that, unlike a true ghost car function, the D143 ghost car requires a controller and uses up one of the three available car ID’s. Personally, I don’t see this as a major issue because, at least in my case, the motivation for doing this is to make racing alone more fun. Also, there is no way to start and stop the ghost car while the controller is set using the rubber band. This means that there cannot be a true starting grid, unless the power is off and then switched on to start the race. Once again, not a big issue for me personally.
• If the D143 ghost car becomes obstructed by a de-slotted car or pileup, be aware that the throttle will continue to apply power. For this reason it is best to clear any obstructions to free the ghost car in a timely manner.
• At the present time I have only two D143 controllers so my testing has been limited to a single (solo) human-controlled D143 car. However, even in this somewhat limited configuration the D143 ghost car significantly enhances the digital racing experience. There is no doubt that running the D143 ghost car with two human-controlled cars would really provide some exciting and challenging racing.
• If a second D143 ghost car is desired it could be created easily by adding a third controller and setting up another D143 car as a ghost car as previously described. However, a superior set up for a solo D143 racer wanting multiple ghost cars could be achieved by installing a D132 decoder chip in a GO!!! or D143 car. The D132 decoder chip can be programmed via the speed controller to run at a constant speed and change lanes randomly on a D143 track. This would enable a fully functional D132 ghost car, a D143 ghost car and a human-controlled D143 car to all run concurrently managed by a single racer. An advantage of this approach is that only two controllers are needed because the programed D132 ghost car uses ID 7. Therefore, the original three D143 ID’s (1,2 and 3) are still available. A future article dealing in detail with the installation of a D132 decoder chip in a GO!!!/D143 chassis will appear on this blog in the near future, so be sure to check back from time-to-time.
• One way to make D143 racing against ghost cars more challenging is to reduce or even eliminate the magnetic down force provided by the traction magnet in the human-controlled car’s chassis. This will make the human-controlled car a little more difficult to control in the turns and will also require an increased level of concentration and skill on the part of the solo racer. Down force can be reduced incrementally by adding thin plastic shims under the magnet in the magnet chamber. Or, the traction magnet can be removed, in which case an aftermarket rear tire such as Jel Claws will be needed in order to provide at least minimal traction on the smooth surface of the Carrera track. If down force is reduced even partially, it will be important to keep the rear set of pickup braids pushed in to a shorter length and possibly splayed a little wider. This may be necessary in order to avoid shorting of the track rails if the car’s rear end slides out in the turns. Setting a car up to run this way will also be discussed in detail in another future article right here.

So, in conclusion I will say that if you spend any significant time running your Carrera Digital 143 slot cars by yourself, you should definitely try this method of adding ghost car(s) to your racing environment. I found it to be very worthwhile and a big step up from merely counting and timing laps when there is no one else to race with. And it requires no modification to the cars, track or any other D143 component, and there is virtually no additional cost other than a sticker and rubber band. There is really nothing to lose.

Thanks to Brian at BRS Hobbies for coming up with this neat idea and making this article possible.

_Michael Ashton