Slot Car Speeds for Windows. Version 3.


Copyright 2005 Rand Fredricksen, Wheeling, IL, USA





This program allows you to vary the voltage, motor speed, the gearing, and the tire size on an electrically powered model car to allow the user to tune the toy for specific conditions.




Unzip the files to your computer. I recommend a new drawer in your Programs folder.



How to prepare:

You will need to know the specific RPMs of a motor. It will be more interesting if you know the specified voltage, but not necessary.

You will want to count the pinion and axle gear teeth.

You will have to know the diameter of the drive tires.



How to use.



The first trackbar gadget allows you to enter the voltage the motor is rated at.


Not the end of the world if you do not know the rated voltage.


If you know the voltage the motor is rated at you can set it in Voltage and Join it to the Motor Speed, after you have selected a Motor Speed. Then, if the track voltage is different than the voltage the motor is rated at, the top speed of the motor will be adapted according to the available voltage when the Join box is checked.


Default is 12 volts.




Slot Car Speeds expects the user to input a motor speed.


There is a combo box below the motor speed gadget which selects from four ranges.


When the voltage and motor speed are related (the Join gadget is checked) the motor speed cannot be modified directly, a variation in voltage will determine the motor speed.


If the voltage is joined to the RPMs and the voltage is raised to a point where the RPM gadget goes out of range the next range is automatically selected.


Default is 18000 RPMs.




You can select a motor gear and an axle gear. The motor gear is referred to as a pinion, while the axle gear is a crown in an inline motor setup or a spur gear with a sidewinder or anglewinder arrangement.


The motor speed is multiplied by the final drive to calculate the speed (RPMs) of the drive axle.


Default is 9:27 (3:1)




The lower numerical the final drive ratio the higher the top speed will be, but acceleration and braking are reduced compared to a higher numerical final drive. A larger numerical final drive ratio will produce more acceleration and braking and is often referred to as lower gearing.


Final drives are usually between 2.7 and 4.3. Oddly enough that is about the same as a full size vehicle.


The reason numerically higher gearing is referred to as a lower gear is that in a vehicle with multiple speeds (a transmission) the lower numbered gears have higher numerical ratios to make starting easier and the higher numbered gears have lower numerical ratios to achieve higher vehicle speeds with lower motor speeds. First gear is the gear most often used to start the vehicle from a stop.




The user must select a tire diameter.


The axle speed (RPMs) is multiplied by the circumference of the tire to determine the distance the toy will travel in a minute.


Default is 5/8 of an inch (.625).




When all these steps are complete the theoretical absolute speed of the toy car is displayed as feet/meters per second.


If you hover the mouse over the output gadget a tooltip will open with actual MPH or KPH.


The motor speed rating is usually for an unloaded motor and many slot cars will never operate at top motor speed. But the relationship between the motor, gears, and tires should be proportional for any one slot car.




Selecting the Metric Checkbox will toggle between English and Metric measurements for tire size and units/second. Millimeters exchange inches or vice-versa.





Displays the version information and author information. It also allows you to view this ReadMe file.





With the Speed being displayed in a trackbar you can quickly see in real time any changes you make to any of the inputs.


Once you drag the arrow near your goal use the cursor keys or the mouse wheel to zero in on the exact target.



Voltage, again.

Once you have input all the relevant parameters click the Join gadget and drag the voltage gadget up and down to simulate operating a slot car controller. ;)






I would appreciate any feedback if you use this program.

Let me know if you need something beyond these limits and within this realm.


Written using PureBasic, a BASIC compiler for Windows, Linux, Amiga, and now Macintosh. Source available upon request.


Copyright 2005 Rand Fredricksen, Wheeling, IL USA. Oh, I said that already.



Thank you!