If I'm having some issues with a loco that moves slightly "jerky" at the lowest speeds (1% to 3%) should I increase the CV or decrease? The current (default) CV is 6 (40%) (00 is off, 15 is 100%)
That may be more an issue with the mechanics of the locomotive (gears, old lubrication, etc.) than the decoder. But, to answer your quessetion: If you increase CV2 the locomotive will start out at a higher voltage/higher starting speed at speed step 001.
What decoder are you using?
Tom
https://tstage9.wixsite.com/nyc-modeling
Time...It marches on...without ever turning around to see if anyone is even keeping in step.
This Technote tells you how to adjust BEMF in Digitrax decoders - tehre are 3 CVs involved, not just the one, and they all interact.
http://www.digitrax.com/tsd/KB902/scaleable-speed-stabilization-back-emf-in-digitrax/
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
Tom, its a Digitrax DN146IP installed on the BLI sound decoder/light board.
Randy, yes, I've seen that. But I must admit I'm still somewhat confused with the three CVs and how they interact. It seems like a lot of experimentation to go through just to get locos running smoothly at very slow speeds. And in this particualr situation (probably not a good choice to start with as a DCC newbie) I'm not really seeing much change in performance when changing the CV's until I set them at an extreme, and then it makes it worse.
There was a desciption in one of the manuals - I think maybe the full decoder manual, you can download it if you didn;t get one with your system. There's a technical way, if you look up the formula for BEMF, there are 3 terms, each CV is one of those terms. But the simpler explanation likens it all to a spring suspencion, one is the strength of the spring, another is like the shock absorber the smooth the rebound, and I forget what it says for the third value. That tech note gives some hints on where to start and what to adjust. Yes, it is a tedious process of adjusting one value at a time. You should be doing this in ops mode, so set the loco to step 1, then adjust the BEMF CVs until it moves slowly and smoothly. As you make the changes in ops mode, they take effect immediately.
Or, you can use ESU Lokpilot decoders - like the Loksounds, they have an automatic configuration for the BEMF, if you have enough track room. You just activate the adjustment sequence and the loco will take off my itself and when complete, the BEMF settings will be optimized.
TCS decoders also have self adjusting BEMF.