Setting max. speed

[2foot6]

I'm trying to set the maximum speed for my locos,with the Bachmann locos I'm having no success.I'm changing cv's 5 and 6 as per other branded chips,any suggestions please.  Peter

[WoundedBear]

Is it a DCC on Board loco? If so, the basic Bachmann decoder doesn't support CV 5 or 6. I'm not sure how you would set max speed on these decoders.

BTW.....NMRA lists CV's 5 and 6 as "optional".

Sid

[Hunt]

Hunt's DCC Rule -- Do not use instructions for brands different from DCC system and DCC decoder your have. 


If decoder Bachmann factory installed - - CV 5 and CV 6 are not supported in the Bachmann OEM Tsunami version decoder installed to date in On30 locomotives. The decoder in the Bachmann On30 does not support a three point speed-step table. It uses an advanced 28 point speed-step table.

First to set maximum  speed for a locomotive
Click Here for
Tsunami Steam Sound User's Guide.  Read Set the User Loadable Speed Curve, page 19

After reading Tsunami Steam Sound User's Guide

Set your command station to send 28 speed steps to the decoder.  Run the locomotive, note which speed step is the top speed wanted.

Method 1 – increasing throttle does not increase locomotive speed once maximum speed reached.
Example:
Speed step 21 (75% full speed) produces the top speed wanted for the locomotive.
Use Table C. Calculating the User Loadable Speed Table find speed step 21. It corresponds to CV 87.
The value of CV 87 = 191. Program each CV above 87 (CV 88 – CV 94) to 191, the CV value of CV 87.

Method 2 – desired maximum speed is not reached until % of throttle.
Program CV  94 to the value representing the top speed. 
Compute the CV step decrease and reprogram C67 through CV 93 with new values
Example:
Speed step 21 (75% full speed) produces the top speed wanted for the locomotive.
Compute CV 94 = (255 x .75  = 191.25) use whole number 191
Compute the values for CV 67 – CV 93
191 / 28 =  6.81 round to 7
Program
CV 94 to 191
CV 93  to  184 ( CV  94 value of 191 – 7)
CV 92 to  177 ( CV 184 value of 184 – 7)
and so on  until
Program CV 67 to  2

Remember program CV 29 to enable speed table use.
Once the speed step table is created, you must program bit 4 of CV 29 to 1 to enable speed table use. Don't yet understand bit programming or your DCC system does not support CV bit programming ; then program CV 29 to 16.

An aside. . .
The Bachmann Sound Value decoder, which is not a Tsunami decoder, does support CV 5 and CV 6

[Hunt]

Typo in my above reply

                   Program CV 29 to 22, not 16.

Remember program CV 29 to enable speed table use.
Once the speed step table is created, you must program bit 4 of CV 29 to 1 to enable speed table use. Don't yet understand bit programming or your DCC system does not support CV bit programming ; then program CV 29 to 16 22.

Also in case you did not pick it up from reading Tsunami Steam Sound User's Guide about Speed Table,  CV 25 must be programmed to value 16 (CV 25 = 16) in addition to programming CV 29 to 22 to use either of the methods I gave. 

[Hunt]

an aside trivia . . .

Hunt's DCC Rule -- Do not use instructions for brands different from DCC system and DCC decoder your have.

BTW – using "your" instead of "you" is part of an insider's joke.   

[Hunt]

Caveat – Method 1

The CV value of CV 67 – CV 94 may not be the same as found in the Tsunami Steam Sound User's Guide, Table C. Calculating the User Loadable Speed Table. Adjust my example for Method 1 accordingly.

[Hunt]

More . . .

Method 2 – desired maximum speed is not reached until % of throttle.

        Should be

Method 2 – desired maximum speed is not reached until 100% of throttle.

[2foot6]

Thank you Wounded Bear and Hunt for you replies,I'm only having problems with the Bachmann chip (non sound)in the  the Davenport and locos I fitted Bachmann chips into.I now have some info to go on and will try  to adjust them in the next few days.cheers Peter.

[Hunt]

Peter,
Don't waste your time.

The 2-function  Bachmann non-sound decoder is a very basic decoder with fixed speed steps and cannot be adjusted except by CV 2 V start. You will need to install a different decoder if you want to set a maximum speed for your locomotive.

[Joe Satnik]

Dear All,

A basic and brute force method of slowing down a DC motor is to add back-to-back diode pairs in series:

Before:
 
Control (+)------------------Motor------------Control(-)

After:

Control(+)---------->l-------Motor------------Control(-)
                       l           l
                       ----l<---

More pairs in series give a greater drop in voltage.

The following Dallee diode bridge circuit is a clever enhancement (multiplication) of the above circuit:

http://www.dallee.com/PDFs/MotorDiodeDrop.pdf

Hope this helps. 

Sincerely,

Joe Satnik

[Linzthom]

Man !! What a lot of rigma-roll !!  I'm so glad I've stuck with dc.

[2foot6]

Hi Linzthom, if I hadn't gone to Dcc ,I would have nothing to do any sanity I had left is being used on DCC