DCC Impulses Column - 9
probably NOT be the same numbers being set in various manu-
facturers' products, as different folks’ decoders have different
sensitivities to the numbers in CVs 3 and 4.
BEMF Settings
Some decoders (TCS, for example) have simple BEMF settings:
on or off. Others (SoundTraxx or Digitrax, for example) have
some very complicated adjustments to fine tune the BEMF set-
tings. These decoders will work if you just enable the BEMF,
but the tweaking makes a big difference in your operation. I
will refer you to your decoder’s instructions. To get Tsunamis to
creep requires the BEMF settings to be adjusted. There is a way
to fix this, but it is beyond this column. Check it out on my web
site in the middle of the Tsunami page
for instructions and a video (10).
BEMF Cutoff
Some BEMF decoders allow BEMF cutoff. This is a way of hav-
ing your cake (low speed BEMF control) and eating it too (no
BEMF at running speeds, to interfere with consisting or cre-
ate a “cruise control”). In its simplest form, the decoder uses a
setting in a CV to tell it above what speed the BEMF control is
disabled, or “cut-off”. The exact settings vary by decoder, but
I would start with the cutoff at 25% of maximum speed and
adjust from there to taste.
BEMF & Consists
There are two points of view for using BEMF with locos that
are going to be consisted: “Yes.” and “No.”! I fall in the “Yes”
category.
I find that with some tweaking, locos can run in consists with
BEMF activated. I believe that folks who say outright, “No.”
haven’t successfully tweaked their locos.
BEMF Cutoff is an help, too. It allows BEMF cotrol for getting
started and no BEMF for locos to fight in the consist at speeds.
I hope you feel a bit less imtimidated by the terms and con-
cepts behind motor control in your DCC decoder.
For more information on these topics, you may consult my
website at the URLs imbedded in this column. There is also
data on the DCC Wiki site (
). When
looking at the DCC Wiki site, please understand that it is a
compilation from lots of folks, so it would be normal for it to
be self-contradictory. Also, the CVs for these adjustments are
not standardized, so any CVs mentioned on the Wiki should
be checked against the documentation for your specific
10: DecoderPro screen: Setting momentum in the
MOTOR tab – This is for a TCS T1. You can see the
BEMF cutoff settings in this tab, too.
10
MRH-Dec 2013
