User's Manual

67
mark one of your magnets with a colored sharpie or piece of tape to reduce the risk of
incorrect counting. Make sure you are measuring using the same units (metric or English) that
the Sensor is currently set up to use.
• Position your car against a wall with the wheels pointed straight ahead. The back end of
the car should be touching the wall.
• Carefully watching the magnets on the shaft, roll the car forward until the shaft has
rotated ten or more (more is better) times. The number of rotations will be your
revolutions parameter.
• Measure from the wall to the back end of the car. If it should work out to an even
number of inches or CM, that will be your rollout parameter. If your measurement is to
the closest 1/8
th
of an inch, then in order to eliminate the fraction, you must multiply
the revolutions by 8 and convert the length to 1/8
th
inches by multiplying the whole
number of inches by 8 and then adding the number of extra 1/8ths. If you are using
metric measurement, it is simple, just multiply CM length and rollout by ten.
Example: Your model was measured to travel 31
5
/
8
” in 10 drive shaft revolutions. This is
equivalent to
251
/
8
” in 10 revolutions, or 251” in 80 revolutions. Thus, the rollout parameter in
should be set to 251, and the revolutions parameter should be set to 80
The higher the numbers you use, the lower your error will be and the more accurate your
speed will be. The maximum value that can be used is 10,000. It may be more convenient to
enter larger numbers using the Digital RC Desktop software.
Since the tach sensor measures only shaft rotation, it does not take into account other issues
like wheel spin, tire expansion at speed, cornering errors, etc.
Setting Tach Parameters
Use the navigation controls to set up the tach sensor as
follows:
1. Access the top function menu
from the driving screen.
menu
2. Navigate to the Advanced
menu.
or : then
3. Navigate to Tach.
or
4. Change the values.
or
Value
Rollout
Revolutions
Description
Units (inches or CM) car rolls in measurement
Number of driveshaft rotations in measurement