Incorporation of TMCC With DCS

Bobby,

DCS and TMCC (or Legacy) work well together on most any layout. However, there are a few TMCCC-related issues of which you should be aware. These, as well as most everything else regarding DCS, are discussed in The DCS Companion 3rd Edition on pages 157-158, as included below:

Some, but not all, TMCC engines will degrade the DCS signal of any DCS engine with which they are in close proximity. This effect varies both by individual TMCC engine and by the distance between the TMCC and DCS engines. In many cases, an RF choke inserted in the Hot wire between the pickup rollers and the TMCC engine's circuit board will correct this problem. 

Some lighted cabooses, most notably those manufactured by Atlas O, may degrade the DCS signal, as may some engines or passenger cars with constant voltage (CV) lighting boards. Again, an RF choke inserted in the Hot wire between the pickup rollers and the circuit board in these cars will generally correct this problem. Although a number of different RF chokes may be effective in reducing interference from CV boards, one that has an electrical value of 22uh (micro henries) is known to work well. 

Lionel TMCC Direct Lockons can also degrade the DCS signal and should not be used with DCS layouts. 

There are two additional ways in which TMCC or Legacy may cause a degradation of the DCS signal. 

The first is if the “one wire” from either the TMCC Command Base or Legacy Command Base is connected to a Common wire that subsequently is connected to a TIU channel input. While there isn’t a lot of data collected in this regard, it makes sense that nothing good can come from passing the TMCC or Legacy signal through a TIU channel's DCS signal generator. 

The second is that there have been reported cases where plugging a TMCC or Legacy Command base into some surge protector power strips can cause, in addition to a degraded TMCC or Legacy signal, a degraded DCS signal, as well. Although the author has had no issues with the Legacy Command Base (or its predecessor TMCC Command Base) being plugged into a surge protector power strip, not all surge protector power strips are the same, and “your mileage may vary” from that of the author. Regardless, if a degraded DCS or TMCC/ Legacy signal is an issue, ensuring that the command base is plugged directly into a 3-prong, grounded AC wall socket is suggested. 

This and a whole lot more is all in “The DCS Companion 3rd Edition!" This book is available from many fine OGR advertisers and forum sponsors, or as an eBook or a printed book at OGR’s web store!

Barry

That was very informative.  Having only one Lionel locomotive and not having had a problem, I did not read that section of your book. Recently, I started to wonder how it was that Lionel locomotives don't louse up the DCS signal.  I have an Atlas and another Legacy locomotive on order and will now know what to look at if I have problems. 

On my layout I have to put the Legacy through the the TIU inputs or it kills the DCS signal

Matt,

On my layout I have to put the Legacy through the the TIU inputs or it kills the DCS signal

That's interesting - that's exactly what not to do!  

It's safest to connect the "one wire" output of the Legacy base directly to the tracks, theCommon output of each TIU channel or to the Common input of each terminal block for the most trouble-free results.

This places the Legacy signal after the TIU signal generators rather than passing it through them.

I understand that Barry and at one point after I got DCS to function well on the layout I attempted to move the Legacy signal wires to the output. My goal is to set myself for the best possible scenarios for DCS. When I did this, it took my DCS signal from mostly 10's with the occasional 9 to 2's and 3's and RF out of range errors during signal testing.

I just finished a major rewire of the entire layout track wiring so now I have  a much more controlled environment to test thsi on so I will move the wires to the output side and see what happens this weekend.

Matt,

I attempted to move the Legacy signal wires to the output .... When I did this, it took my DCS signal from mostly 10's with the occasional 9 to 2's and 3's and RF out of range errors during signal testing.

Honestly, I'd attribute your signal strength issues to something other than the way you had Legacy connected to the layout.

Barry,

Thank you for your responses, and I learned something. I was not aware of the necessity for a 22uh Coil (AKA Choke) between the rollers and boards of TMCC locomotives.

My railroad is wired using your guidance in the DCS Companion, and signal strength readings are consistently 9 and 10 throughout 300+ feet of Real Trax including single ended sidings. PS 2 & PS3 locomotives run so well on my railroad that I will not be able to tolerate any degradation from TMCC.

My plan is to try one TMCC locomotive, most likely a Lionel NYC S1 or S3 when I find one for sale.

Bobby,

I was not aware of the necessity for a 22uh Coil (AKA Choke) between the rollers and boards of TMCC locomotives.

Just do the ones that actually cause issues with DCS signal strength. Not all TMCC and Legacy engines cause DCS signal problems.

Thanks Barry.