Step 3: Configuring the Throttle
There are seven CVs that characterize the Tsunami’s throttle response and 28 more used to create a custom speed table:
CV 2, VStart CV 3, Acceleration Rate CV 4, Braking Rate CV 25, Speed Table Select CV 29, Configuration Data CV 66, Forward Trim CV 95, Reverse Trim CV 67-94, Loadable Speed Table
This may sound like a lot of CVs but don’t worry; it’s not necessary to change all of them if you don’t want to. We’ve already talked about speed step selection in CV 29 (Step 2).
Set the Start Voltage
Tsunami provides CV 2, Vstart, to set the starting voltage that is applied to the motor at Speed Step 1 and is used to compensate for inefficiencies in the locomotive’s motor and driveline. CV 2 may be programmed with any value between 0 and 255 with each step in value being about 0.5% of the maximum available motor voltage. To calculate the value of CV 2, you can use the formula:
Desired Starting Voltage CV 2 = 255 X —————————————— Maximum Motor Voltage
If your DCC system supports Operations Mode Programming, an alternative method for setting Vstart is to turn your throttle to the first speed step and then use the operations mode programming feature to increase the value in CV 2 until the locomotive just begins to move.
Set the Acceleration and Braking Rates
Tsunami provides two CVs to simulate the momentum due to train weight. CV 3, Acceleration Rate, controls how fast the locomotive responds to increases in throttle settings and CV 4, Braking Rate, controls how fast the locomotive will respond to decreases in the throttle setting.
Both CVs can be programmed with any value between 0 and 255 with 255 corresponding to the slowest acceleration or braking rate. Lower settings yield a more responsive locomotive, which is useful for switching. When both CVs are set to 0, the locomotive will respond nearly instantly to any throttle changes. A setting of 255, on the other hand, will require several minutes for a locomotive to reach full speed from a standing stop!
Tsunami’s Dynamic Digital Exhaust feature will be more dramatic if you use
Tsunami Steam Sound User’s Guide