Lawrence Varady

I have an N scale KATO track system using an NCE PowerCab(no boosters) and all NCE hardware for DCC and JMRI.

1.  Has anyone experienced this problem:
     I have 12 SKs that are Rev C or E and are the smaller thinner PCBs.

     I have 4 SKs that are Rev B and are the Longer thicker PCBs. These 4 SKs produce the OPPOSITE (N & R) LED OUTPUTS from the 12 SKs?

2.  I wanted to know how users are providing switch position feedback to JMRI since the NCE Switch-Kats DO NOT provide any feedback other than LED OUTPUTS.
     I built a circuit that uses the LED OUTPUTS to provide a switch position feedback signal to my AIUs for use with JMRI.

Any info would be greatly appreciated.

John Eldridge

Hi Vic, 


Have a Kato UniTrack layout with 20-220 & 20-221 turnouts that started with NCE PowerCab, no added boosters, NCE AIU’s, BD20's, and Switch-Kat’s to operated the Kato turnouts. 


As the Kato turnouts can be manually set, and the Switch-Kats can be locally set with external pushbuttons, and this is planned as a fully automated layout using iTrain software, I wanted to read how the turnouts are really set rather than how they were told to be set. 


The Switch-Kat “N” & “R” LED outputs do tell how the Switch-Kats are set, but not how the turnout is set manually. 


As the Kato turnouts do have “frog” voltage switching builtin, I thought that reading the “frog” voltage compared to one of the thru rails would definitively confirm the turnout position. Conceived an opto coupled circuit that will read the “frog” voltage, whether AC, DC, or DCC, convert it into DC to the emitter LED in an opto coupler, which would turn on the receiver transistor in the opto coupler, which would pull the Input of a NCE AIU Cab Bus Interface to ground to tell the iTrain automation software how the turnout is really set!  


After building and proving the test ciruit actually works, discovered that Terry Chamberlin of A-Track software had already designed a DCC specific version exactly the same as my design, and had already designed DCC-AIU Link pcbs that could be ordered premade, and a complete parts list for the pcb components to build the opto-coupler interface for [8] turnouts. 


The detailed info for Terry’s interface is in section 14.2 on pages 474-480 of his A-Track Reference Manual available @


The pcb Terry designed is available for order directly from the pcb fabricator OSH Park @  The pcb is @ 

These DCC-AIU Link pcb circuits worked perfectly with the NCE System. 


As my NCE PowerCab DCC System would not fully connect and communicate with the iTrain automation software, had to replace with ESU ECoS based DCC System hardware, but the DCC-AIU Link pcbs continue to work just fine with the ESU DCC System as well. 


This is my solution to reading actual Kato turnout position on a DCC layout regardless of how the turnout is controlled. To function, the DCC Track power must be ON to provide the “frog” voltage.


Hope this helps answers your question, please advise if questions, John