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Adding ditch lights to TMCC Locomotives using the ERR Sound Converter.

I've done some code mods to the ERR Sound Converter to get properly working ditch lights.  Although not in the documentation for the Sound Converter, there are three LED outputs on the six-pin connector, two of those LED's provide ditch light functionality.  I recently wanted to use ditch lights in an upgrade, so I set about fixing the functionality so it would be suitable, there were a couple of issues with the "as delivered" code.  Here is the latest version of my code.

ERR Sound Converter Ditch Light

The Sound Converter should be connected as documented as far as serial data and power, the ditch lights are connected using a 1.5mm 6-pin JST-ZH family connector.  Below is a snippet of the schematic for the ERR Sound Converter board, LED#1 and LED #3 are the ditch light outputs, pins 1 & 5 are the positive side.  No resistors required, each output drives one white LED.

One installation note.  In certain environments, the Sound Converter will load the serial data enough to cause issues with other serial functions, specifically sounds and/or motor control in the case of the ERR Cruise Commander M.  This is because the standard connection to the Sound Converter drives the serial data through an opto-isolator, and the serial data is required to supply the power for the opto-isolator.  There is a work-around for this, if you move the serial data line from pin-1 of the 4-pin connector to pin-3, it drives an unbuffered input.  This reduces the load and allows other serial data users to see the serial data.  Since the serial data for TMCC is frame ground referenced, this shouldn't create any issues, and it's worked fine for me.

 If you are not using the actual Sound Converter feature of the board to drive a conventional sound board, you can also remove the rather large and bulky LM317 regulators to make a more compact package.  I do that, and then I stick the whole board in a piece of heatshrink to insulate it.

Obviously, not everyone is setup to compile and program the board, so if you want this functionality, you can contact me and we'll work out an update for your Sound Commander code.


Last edited by gunrunnerjohn

The original Lionel TMCC system came with a list of commands that could be sent to the serial port on the command base from a computer. Is there a similar list for the Legacy system? I am trying to add some of the new command strips to JMRI so I can expand control capabilities of JMRI for Legacy equipped rolling stock. Cannot seem to find this info anywhere. 

@Mike CT posted:

From a Recent tread.  TMCC 101

If you can find a CAB-1/Command Base, the original TMCC offering,  here is a link from the Lionel website.  A 48 page manual that was part of the Cab-1 handheld/Command base offering.   The complete guide to command control.  Click on the underlined phrase to link.
Here is a link to the Legacy Control System V 1.5.  88 page manual

Both manuals have just about everything that is involved with the two systems. Basic wiring to multiple unit/locomotive operations.

Another important part of the system is the Track Power Controller.  It allows for Conventional control using hand held remotes.

Edit/add: The TPC (Track Power Controller) has the ability to interface with QSI/MTH Proto1 and Proto2 in conventional mode. Noted in this publication. Simple commands like horn/whistle, couplers, etc. are available via the Cab1 handheld control buttons.  Pages 17,18,19.   

There are other control devices related to accessory and block controls, that more or less piggy-back off either of the two command systems.

Lots of infomation in those three underlined phrases.
Have fun

Both these links are dead.  We should start a wiki where people can update links etc.

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