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Involves Slot Cars , Transformers and 2 cars on each track

  1. Nov 1, 2013 #1
    I had a new slot car race track with step down transformer given to me by my Grand Parents for a birthday present.

    One thing I did notice, is the car with the lowest internal resistance motor used to go faster, well that's what my Dad told me at the time. I found this to be very true on a friends track.

    Later on when I was given lots of slot car track, controllers and cars to play with.

    After a while, I was able to modify and rewire certain components and have 2 cars on the same track.

    I am building another prototype just for when I get tired of the computer..

    It was a lot of years ago so I was wondering if anybody would like to help me come up with a circuit that works so I don't need to do it all again.
  2. jcsd
  3. Nov 5, 2013 #2


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    It would be important that two cars on the same track have the same track speed.
    A DC motor will run at a maximum speed determined by the supply voltage which is shared by the two cars.
    The motor voltage to speed ratio, plus the gear ratio and wheel size all have to be taken into account.
  4. Nov 5, 2013 #3


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    Two cars on the same track is easy. Just put them on the same track. Obviously you mean something different than that but I'm not sure what.

    Assuming you are varying the track voltage to control the car's speed, I don't see any simple way to independently control 2 cars on the same track, if that is what you mean.
  5. Nov 9, 2013 #4


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    The simplest way to independently control two cars on the same track is to fit a power diode in series with each car's motor. The direction of that diode decides if the car will run only on the positive or only on the negative of the low voltage AC power supply.

    The AC supply circuit must also be modified, with one side of the transformer secondary now being connected directly to the track. The other terminal of the transformer secondary is connected to a pair of opposed power diodes that feed the two hand controller rheostats, both of which are then combined again to feed the track. One hand controller therefore controls the positive phase current while the other controls the negative phase current. That then gives independent control of up to two cars on the same track.

    Nowadays, many digital and WiFi solutions are available to the problem of independent speed control of several cars on the same track.

    Where cars have different resistance motors, the track voltage and available current from the controller must be adjusted to get the best performance.
  6. Nov 9, 2013 #5


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    I was thinking of something similar baluncore. Something like this would require changing the magnets around in the car also. They have always been permanent magnet fields as far as I know. I cannot see the advantage of running two cars on the same track (technically the same lane) since one cannot pass the other anyway. I am surprised slot cars interest anyone anymore. I know back in the day I had a lot of fun with mine. If I dig far enough I can come up with all the pieces.
  7. Nov 10, 2013 #6
    Yes Many thanks, also if you fit a Capacitor in as well to smooth the half wave current on the motor out it works a bit better.
  8. Nov 10, 2013 #7


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  9. Nov 10, 2013 #8
    Ok What happens if you put the 2 cars back to back on the track with the same people using the controllers?
  10. Nov 11, 2013 #9


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    They will both run forwards on the same controller and phase until they collide head on about half way round the track.
  11. Nov 19, 2013 #10
    Yep Demo Derby.
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