### Programming Speed Tables

greenspun.com : LUSENET : Wiring for DCC : One Thread

I am having a hard time finding info on advanced programming of Decoders. I am attempting to tune the speed curves on my various engines to support consisting and multiple train operations, limit top speed for Younger children and "newbies", and trying to make speed adjustments more controller friendly. Any idea where I can get more detailed info on this, or possibly some Downloadable speed tables to try out (if they match my eng/decoders) or use as examples?

Any help is appreciated.... Ken

-- Kenneth Coe Jr (iken@provide.net), December 07, 2003

re – Matching Loco Speeds and Speed Tables The goal is to adjust the DCC decoders in individual locos so that they will all run at the same speed in a consist and receiving the same speed step command.

The problem is that every brand and model of loco you purchase has a different voltage/speed profile...AND most of them run way too fast. Compounding this problem is that each brand and model of DCC decoder will act differently to the same speed table data. This makes it impossible to just load in the same speed table data and get the same running speed result from a random selection of locos and decoders. The basic steps are relatively simple.

Step 1 – Decide on a target step-speed profile. Determine the desired top speed for your fleet and a way to measure it. Prepare a notebook for recording your criteria and data records for each loco. For each loco then...

Step 2 – Clean and adjust the loco gears. If new, run the locos for several hours at mid speed in both directions to help seat gear teeth and motor brushes.

Step 3 – Determine the minimum speed decoder set-point value. Do this by using 'Speed 1' of the loadable alternate speed table (or the Minimum Speed CV if you choose to go that route). Home in on a value that just gets the loco to creep at the lowest possible speed. This is the time to fiddle with the decoder frequency, Kick-Start CVs, BEMF, or other features of your decoder as making those adjustments later will most likely change the data required in the speed table to meet your desired uniform speed profile. Step 4 – Determine the maximum speed set-point value for 'Speed 28' (or Max Speed CV). Again, manipulate the speed value data to yield the desired top running speed.

Step 5 – Load your observed values of Vmin and Vmax into a spreadsheet to calculate Vmid and the other 25 values. Let a computer calculate all the in-between values. Then load them into the decoder. Record these values in your notebook (or in a computer file).

Repeat Steps 2-5 for every loco that you intend to consist together. When completed, all locos should run at nearly the same speed from the same DCC speed step command.

I'll send you an Excel spreadsheet to help calculate CV data.

-- Don Vollrath (dvollrath@magnetek.com), December 08, 2003.

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